A revision of the Early Jurassic ichthyosaur Hauffiopteryx (Reptilia: Ichthyosauria), and description of a new species from southwestern Germany

Abstract

Hauffiopteryx typicus is an Early Jurassic ichthyosaur species from Europe, for which geographically partitioned morphological variation between specimens from England and Germany has been described. We provide a complete anatomical description of the German material to address this taxonomical issue. We also identify and describe a new species of Hauffiopteryx from the southwest German Basin, Hauffiopteryx altera sp. nov., differring from H. typicus in the morphology of the arrangement of cranial elements surrounding the external nares. A phylogenetic analysis recovers the German and English material referred to H. typicus as sister taxa, suggesting that these are indeed conspecific. H. typicus forms a monophyletic group with H. altera and a specimen from the Pliensbachian of Switzerland previously referred to Leptonectes tenuirostris but consistent with H. typicus. We conclude that Hauffiopteryx represents a valid genus, defined by a set of synapomorphies from both the skull and postcranium. Parsimony analysis recovers Hauffiopteryx as sister taxon to Stenopterygius + Ophthalmosauridae.

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Maxwell, Erin E. and Cortés, Dirley. 2020. A revision of the Early Jurassic ichthyosaur Hauffiopteryx (Reptilia: Ichthyosauria), and
description of a new species from southwestern Germany. Palaeontologia Electronica, 23(2):a29. https://doi.org/10.26879/937
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A revision of the Early Jurassic ichthyosaur Hauffiopteryx
(Reptilia: Ichthyosauria), and description of a new species
from southwestern Germany
Erin E. Maxwell and Dirley Cortés
ABSTRACT
Hauffiopteryx typicus is an Early Jurassic ichthyosaur species from Europe, for
which geographically partitioned morphological variation between specimens from
England and Germany has been described. We provide a complete anatomical
description of the German material to address this taxonomical issue. We also identify
and describe a new species of Hauffiopteryx from the southwest German Basin, Hauf-
fiopteryx altera sp. nov., differring from H. typicus in the morphology of the arrange-
ment of cranial elements surrounding the external nares. A phylogenetic analysis
recovers the German and English material referred to H. typicus as sister taxa, sug-
gesting that these are indeed conspecific. H. typicus forms a monophyletic group with
H. altera and a specimen from the Pliensbachian of Switzerland previously referred to
Leptonectes tenuirostris but consistent with H. typicus. We conclude that Hauffiopteryx
represents a valid genus, defined by a set of synapomorphies from both the skull and
postcranium. Parsimony analysis recovers Hauffiopteryx as sister taxon to Stenopte-
rygius + Ophthalmosauridae.
Erin E. Maxwell. Staatliches Museum für Naturkunde, Rosenstein 1, 70191 Stuttgart, Germany,
erin.maxwell@smns-bw.de
Dirley Cortés. Redpath Museum, McGill University, 859 Sherbrooke St. W., Montreal QC H3A 0C4,
Canada. Smithsonian Tropical Research Institute, Balboa-Ancón 0843–03092, Panamá, Panamá.
dirley.cortes@mail.mcgill.ca
Keywords: Hauffiopteryx; new species; Posidonienschiefer Formation; Germany; Toarcian; Early Jurassic
Submission: 2 November 2018. Acceptance: 12 June 2020.
INTRODUCTION
The Posidonienschiefer Formation (Posido-
nia Shale) of southwestern Germany is considered
one of the classic Mesozoic marine fossil lager-
stätte, and has yielded thousands of exceptionally
preserved fish and reptile remains (Urlichs et al.,
1994). The fossil marine reptiles, in particular, have

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
2
garnered a great deal of research attention. The
most abundant and best-preserved of these are
the ichthyosaurs, represented in museum collec-
tions by hundreds of specimens including exam-
ples with fossilized soft-tissues, gastric contents,
and embryos preserved inside the body cavity
(Hauff, 1921; Böttcher, 1989, 1990). The first ich-
thyosaur formally named from the Posidonia Shale
was Temnodontosaurus trigonodon, named over
175 years ago (Theodori, 1843), and the most
recently erected species still regarded as valid
were named almost 90 years ago (Stenopterygius
uniter von Huene, 1931 and Hauffiopteryx typicus
[von Huene, 1931]). Ongoing research has empha-
sized questions pertaining to paleobiology, includ-
ing intraspecific variation (e.g., Maxwell, 2012a),
ontogeny (e.g., Dick and Maxwell, 2015), diet (e.g.,
Dick et al., 2016), and prevalence of skeletal
pathologies (e.g., Pardo-Pérez et al., 2019). The
discovery of new species following so many years
of intensive research effort was thought to be
unlikely.
The monotypic genus Hauffiopteryx (Maisch,
2008) is the most recently named and least distinc-
tive ichthyosaur genus from the Posidonienschiefer
Formation. The genus has a convoluted history.
Hauffiopteryx typicus (von Huene, 1931) was ini-
tially referred to Stenopterygius as S. hauffianus /
S. hauffianus forma typica due to its small size and
similarities in forelimb morphology (von Huene,
1922, 1931); the unusual morphology of the pelvic
girdle was interpreted as an abnormality
(McGowan, 1978). Maisch (2008) recognized
Hauffiopteryx as distinct from Stenopterygius
based on the small, round temporal fenestra,
extensive gastralia, and medially unfused pelvic
girdle. He considered Hauffiopteryx to be nested
within Thunnosauria, potentially forming a sister
group to Stenopterygius + Ophthalmosauridae.
This hypothesis was supported by subsequent cla-
distic analyses (Fischer et al., 2016; Moon, 2017).
However, Hauffiopteryx has also been recovered in
a more basal position, as sister group to Thunno-
sauria (Ji et al., 2016).
Maisch (2008) initially identified seven speci-
mens referable to Hauffiopteryx typicus: one from
the Toarcian of the UK, five from southwestern
Germany, and one from Luxembourg. We were
unable to examine the latter skull personally but
consider most likely referable to the more abun-
dant genus Stenopterygius based on the apparent
exclusion of the prefrontal by the lacrimal from the
posterior edge of the external nares (Godefroit,
1994: pl. 3a). Two additional specimens from the
Toarcian of the UK were later referred (Caine and
Benton, 2011). The specific referral of BRLSI M
1399, part of the original referred material cited by
Maisch (2008), was later questioned following CT-
scanning and detailed description, as it failed to
form a monophyletic group with H. typicus in phylo-
genetic analysis (Marek et al., 2015). This raised
questions of provincialism and endemism among
Early Jurassic ichthyosaurs that can only be
resolved by restudy of the German material.
In addition to the material from the Toarcian of
Germany and the UK, a small skull from the Pliens-
bachian of Switzerland (NMO 26575) referred to
Leptonectes tenuirostris was described as varying
from the typical morphology observed in Hettang-
ian–Sinemurian specimens of L. tenuirostris by a
series of features such as small size, shorter ros-
trum, participation of the prefrontal in the external
narial opening, and notching of the forefin ele-
ments (Maisch and Reisdorf, 2006). These charac-
ters are now known to differentiate Hauffiopteryx
and Leptonectes, thus meriting reevaluation of the
taxonomic affinities of NMO 26575. Problemati-
cally, L. tenuirostris was partially scored based on
NMO 26575 in the analysis of Moon (2017), and
possibly other analyses as well.
Here, we provide a complete anatomical
description of Hauffiopteryx from the Southwest
German Basin. We re-examined the five speci-
mens cited by Maisch (2008), and included five
additional specimens from the collections of the
SMNS, GPIT, and the Werkforum Dotternhausen.
This study led to the recognition of a second spe-
cies of Hauffiopteryx from southwestern Germany,
Hauffiopteryx altera sp. nov. We also reconsider
the affinities of NMO 26575 from the Early Jurassic
of Switzerland described as Leptonectes tenuiros-
tris by Maisch and Reisdorf (2006), which shares
many morphological similarities with H. typicus.
MATERIAL
We re-examined the five specimens cited by
Maisch (2008) as referable to Hauffiopteryx typi-
cus: GPIT 1491/4 (bed number εII4, Holzmaden),
MHH 9 (bed number εII4/5, Holzmaden), SMNS
51552 (εII3, Zell unter Aichelberg), SMNS 80225
(εII4, Schlierbach), and SMNS 81965 (εII4, Schlier-
bach). We also studied an additional six specimens
that we considered to be referable to Hauffiopteryx
based on the diagnosis of Maisch (2008): SMNS
81367 (a small skeleton in left lateral view lacking
the pelvic girdle and anterior caudal region, from
bed number εII4 of Schlierbach, Baden-Württem-

PALAEO-ELECTRONICA.ORG
3
berg), SMNS 80226 (a partial skeleton in ventral
view with pectoral girdle, gastralia and ribs pre-
served but lacking the hind limbs, from bed number
εII4 of Schlierbach, Baden-Württemberg), SMNS
81962 (an almost complete skeleton in ventral
view, including a partial skull, pectoral girdle and
limbs, from bed number εII3, Ohmden), GPIT/RE/
12905, a moderately compressed skull from an
unknown locality and horizon of the Posidonien-
schiefer Formation, and FWD-129 (Dotternhausen-
Dormettingen, εII4/5), a lightly compressed skull,
pectoral girdle and anterior vertebral column pre-
served in a concretion, previously considered to be
a juvenile of Eurhinosaurus longirostris (Jäger,
2005). We also restudied NMO 26575, a three-
dimensional skull and some associated postcranial
elements from the upper Pliensbachian of Hauen-
stein, Switzerland, previously referred to Lep-
tonectes tenuirostris but varying in several
characteristics now more suggestive of Hauffiop-
teryx Maisch, 2008, such as small size and closely
packed forelimb elements with anterior notches
(Maisch and Reisdorf, 2006).
Institutional Abbreviations
BRLSI, Bath Royal Literary and Scientific Institu-
tion, Bath, UK; FWD, Werkforum, Dotternhausen-
Dormettingen, Baden-Württemberg, Germany;
GPIT, Palaeontological Collections of Tübingen
University, Tübingen, Germany; MHH, Museum
Hauff, Holzmaden, Germany; NMO, Naturmu-
seum Olten, Switzerland; SMNS, Staatliches
Museum für Naturkunde Stuttgart, Germany.
SYSTEMATIC PALEONTOLOGY
ICHTHYOPTERYGIA Owen, 1859
ICHTHYOSAURIA Blainville, 1835
PARVIPELVIA Motani, 1999
HAUFFIOPTERYX Maisch, 2008
Type species. Hauffiopteryx typicus (von Huene,
1931)
Revised generic diagnosis. A small- to mid-sized
ichthyosaur, 2–3 m in length, with relatively short
and slender antorbital rostrum; slight overbite pres-
ent (unlike Eurhinosaurus, Excalibosaurus in which
a substantial overbite is present); prefrontal partici-
pating in margin of external naris (unlike Eurhino-
saurus, Leptonectes, Stenopterygius); nasals with
a greater contribution to the dorsal midline of the
rostrum anterior to the external narial opening than
the premaxillae (unlike Stenopterygius); prefrontal
with larger external exposure on dorsal skull roof
than the postfrontal (unlike Stenopterygius); pari-
etal foramen situated anterior to the supratemporal
fenestra (situated at the same level as the anterior
edge of the supratemporal fenestra in Stenopteryg-
ius); supratemporal fenestra small and circular in
dorsal view (similar to Eurhinosaurus but unlike
Stenopterygius); supratemporal palmate in pos-
terodorsal view (similar to Eurhinosaurus, unlike
Stenopterygius); teeth with smooth enamel (unlike
Suevoleviathan); gastralia extending posteriorly to
the thirty-fifth presacral vertebra (unique feature
among Toarcian ichthyosaurs); rib tuberculum and
capitulum widely separated in the dorsal region
(unlike Temnodontosaurus, Suevoleviathan, Eurhi-
nosaurus); glenoid end of scapula anteriorly
expanded (unlike in Temnodontosaurus); coracoid
with anterior notch, foramen between humerus,
radius, and ulna absent (unlike Suevoleviathan,
Temnodontosaurus trigonodon); anterior digit in
both fore- and hindfins with notches on the anterior
edge (unlike in Suevoleviathan); proximal limb ele-
ments angular and forming a tightly articulated
mosaic; ischium and pubis thin and styloidal, fused
laterally but widely separated medially (autapomor-
phic); fibula larger than the tibia; hindfin digits con-
verging distally.
Hauffiopteryx typicus (von Huene, 1931)
Figures 1-5
Lectotype. GPIT 1491/4; a complete skeleton with
partial preserved soft-tissue outline in left lateral
view. GPIT 1491/4; a complete skeleton with partial
preserved soft-tissue outline in left lateral view
(Figure 1A).
Geographical distribution. Baden-Württemberg,
Germany; Ilminster (UK) (Maisch, 2008); Solo-
thurn, Switzerland (see discussion for details).
Stratigraphic distribution. Late Pliensbachian,
margaritatus Zone; lower Toarcian, tenuicostatum
Zone, semicelatum Subzone–serpentinum Zone,
exaratum Subzone (SWGB: beds εII3-εII4/5). Note
that according to the specimen label, SMNS 51552
originates from bed εII3, rather than εII2 as stated
elsewhere (Maisch, 2008). Peak abundance
occurs in εII4, where material referred to Hauffiop-
teryx represents a substantial percentage of all
small ichthyosaurs recovered (Maxwell and Vin-
cent, 2016).
Emended diagnosis. Hauffiopteryx typicus can be
distinguished from other species of Hauffiopteryx
by a triradiate lacrimal forming the posterior border
of the external narial opening, deepest lateral
exposure of the maxilla located ventral to the pos-
terior half of the external narial opening, a large,

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
4
rounded orbit, and nasals with pronounced dorsal
inflection at the anterior orbital margin.
Referred specimens. Of the material examined,
GPIT 1491/4, GPIT/RE/12905, MHH 9, SMNS
51552, and SMNS 80226 can be confidently
referred to H. typicus (Figures 1-3). The English
material referred to Hauffiopteryx is also consistent
with H. typicus, as is NMO 26575 from the Pliens-
bachian of Switzerland (see discussion for details).
DESCRIPTION
The description is based on GPIT 1491/4,
GPIT/RE/12905, MHH 9, SMNS 51552, and SMNS
80226; selected measurements can be found in
Appendix 1. Variation in the shape of the posterior
premaxilla and anterior lacrimal in GPIT/RE/12905
is attributed to differences in preservation and
intraspecific variation between this and the other
skulls; these variants are clearly noted in the
description. The English and Swiss material is
excluded from the description.
Premaxilla. The premaxilla is gracile and dentiger-
ous, decreasing rapidly in depth anteriorly (Figure
2A-2C). Posteriorly, a subnarial process extends
ventral to the anterior portion of the external narial
opening. A robust, extensive supranarial process is
absent; however, in GPIT/RE/12905 a slender pro-
cess is present (Figure 3A). It is shorter than the
subnarial process, and extends less than one quar-
ter of the length of the external narial opening.
Although apparently absent in GPIT 1491/4, MHH
9, and SMNS 51552, the quality of preservation of
this region in these specimens does not preclude
the erosion of such a delicate bony structure
through either taphonomic processes or prepara-
tion. The premaxillary fossa is deepest at its mid-
FIGURE 1. Hauffiopteryx typicus. A, lectotype, GPIT 1491/4; B, SMNS 51552; C, SMNS 80226. Part 1B © SMNS / M.
Wahler.

PALAEO-ELECTRONICA.ORG
5
FIGURE 2. Hauffiopteryx typicus, cranial morphology. A–G, overview of cranial morphology. A, lectotype, GPIT 1491/
4; B, SMNS 51552; C, MHH 9; D, SMNS 80226. E, basioccipital in ventral view (SMNS 80226); F, maxillary and poste-
rior dentary teeth (GPIT 1491/4); G, anterior mandible with displaced teeth (SMNS 80226). Scale bars in cm (parts B,
D, E). Abbreviations: an, angular; bo, basioccipital; de, dentary; hc, hyoid corpus; hy, hyoid element; en, external narial
opening; ex, exoccipital; f, frontal; j, jugal; la, lacrimal; lj, lower jaw; mx, maxilla; n, nasal; op, opisthotic; pa, parietal;
pal, palatine; pf, prefrontal; pl, palate; pm, premaxilla; po, postorbital; pof, postfrontal; pt, pterygoid; Q, quadrate; qj,
quadratojugal; sa, surangular; scr, sclerotic ring; sp, splenial; sq, squamosal; st, supratemporal; s, stapes; utf, supra-
temporal fenestra.

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
6
point, becoming rapidly shallower posteriorly. The
premaxillary rostrum is short in all diagnostic mate-
rial, with prenarial segment ratios of ~0.49 (GPIT/
RE/12905), 0.48 (MHH 9), ~0.42 (SMNS 80226),
and ~0.37 (GPIT 1491/4). The rostral tips (both
premaxillary and mandibular) of SMNS 51552,
often cited as an example of Hauffiopteryx with a
long rostrum (Maisch, 2008), are of problematic
authenticity; as preserved the prenarial segment =
0.46.
Maxilla. The maxilla in H. typicus is short, and
does not extend more than a few millimeters ante-
rior to the external narial opening in lateral view
(Figures 2A-2C, 3A). The dentigerous portion con-
tinues posterior to the external narial opening. The
maxilla forms the ventral edge of the external narial
opening in most specimens, but is excluded in
FIGURE 3. Hauffiopteryx typicus, cranial morphology of GPIT/RE/12905. A, lateral view; B; dorsal view of posterior
skull roof. Abbreviations: an, angular; bo, basioccipital; de, dentary; en, external narial opening; ex, exoccipital; f, fron-
tal; j, jugal; la, lacrimal; mx, maxilla; n, nasal; pa, parietal; pf, prefrontal; pm, premaxilla; po, postorbital; pof, postfron-
tal; sa, surangular; scr, sclerotic ring; sq, squamosal; st, supratemporal; utf, supratemporal fenestra.

PALAEO-ELECTRONICA.ORG
7
GPIT/RE/12905 by contact between the premaxilla
and lacrimal. An ascending process posterior to
the narial opening is absent. The orbital process of
the maxilla is moderately elongated, but does not
reach the orbital mid-point and is shorter than the
suborbital process of the lacrimal. Anteriorly, the
maxilla is dorsally overlapped by the premaxilla.
Posteriorly, it contacts the jugal and lacrimal.
Nasal. The nasals are exposed dorsally over
approximately two thirds of the antorbital rostrum
(Figure 2A, 2C). The presence of an internasal
foramen could not be evaluated in the extremely
compressed material, but an internasal depression
was certainly present medial to the external nares.
The nasal forms the dorsal edge of the external
narial opening and contacts the prefrontal at the
posterodorsal edge of the external narial opening.
On the dorsal skull roof, the nasals contact the pre-
frontal laterally and the frontal posteriorly. A small,
superficial contact between the nasal and the post-
frontal, overlapping the prefrontal, may occur pos-
terolaterally (Figure 2C).
Lacrimal. The lacrimal is small, with a very short
subnarial process in most skulls (Figure 2A-2C). It
usually participates in only the posteroventral cor-
ner of the external narial opening. However, in
GPIT/RE/12905 the subnarial process of the lacri-
mal is slender but elongate, extending over more
than half the total length of the external narial
opening to contact the subnarial process of the
premaxilla (Figure 3A); we consider this to be intra-
specific variation, as documented in other Early
Jurassic ichthyosaur species (see discussion). The
suborbital process of the lacrimal articulates ven-
trally with the jugal and is relatively elongate. The
suborbital process is separated from the lateral
portion of the element by a ridge, forming part of
the circumorbital area. The ascending process
contacts the prefrontal via an interdigitating suture,
and does not contact the nasal.
Jugal. The jugal is a relatively slender, deeply
bowed element. It is overlapped by the postorbital
posterolaterally, excluding the ventral postorbital
from the posterior edge of the orbit (Figures 2A-2C,
3A). The dorsal process of the posterior jugal is
narrow and mediolaterally compressed, lacking
pronounced anteroposterior expansion. Anteriorly,
the jugal narrows, and slots between the lacrimal
and maxilla. It does not reach the external narial
opening.
Prefrontal. The prefrontal forms a large narial pro-
cess, and participates extensively in the posterior
portion of the external narial opening (Figure 2A-
2C). It forms approximately 50% of the dorsal
orbital margin. The prefrontal extends medially to
contact the frontal, but may be overlapped by pro-
cesses of the postfrontal and the nasal.
Frontal. The frontals are relatively narrow and
slightly convex, tapering anteriorly. They form the
external anterior and lateral margins of the parietal
foramen (Figure 2A, 2C).
Parietal. The parietal forms approximately half of
the anterior edge of the supratemporal fenestra
(Figure 2A, 2C). The medial process of the supra-
temporal excludes the parietal entirely from the
posteromedial edge of the fenestra, best seen in
GPIT/RE/12905. The interparietal suture is
straight. A weak ridge separates the posterior lam-
ina from the dorsal surface of the parietal. A weakly
developed ridge lateral to the parietal foramen runs
anterolaterally to posteromedially.
Postfrontal. The postfrontal forms the anterolat-
eral margin of the supratemporal fenestra (Figure
2A, 2C). It interdigitates with the supratemporal
along the posterolateral margin of the supratempo-
ral fenestra. The postfrontal overlaps the postor-
bital along the dorsal edge of the orbit.
Postorbital. The postorbital makes up the poste-
rior edge of the orbit (Figure 2A-2D). It is a narrow
semi-lunate element. It contacts the squamosal
posteriorly, and the supratemporal dorsally, with a
very small anterodorsal contact with the postfron-
tal. Ventrally, the postorbital is excluded from the
orbital margin in all specimens by the ascending
process of the jugal.
Supratemporal. The supratemporal is large, form-
ing a posterior lamella with radiating ridges, giving
it a scalloped appearance in external view (Figure
2A, 2C). These ridges correspond to the anterome-
dial and anterolateral processes of the anterior
ramus, as well as to small medial and lateral pro-
cesses of the medial ramus. A well-developed ven-
tral ramus is present. It is not significantly longer
than the medial or lateral processes.
Squamosal. The squamosal is well-preserved only
in GPIT/RE/12905 (Figure 3). It is exposed on the
posterolateral skull and is roughly triangular in
shape, with a descending process posterior to the
postorbital. Dorsally it contacts the supratemporal.
Quadratojugal. The ventral portion of the quadra-
tojugal is preserved in the lectotype (Figure 2A). In
external view, it appears to be excluded from con-
tact with the jugal by the postorbital, but this could
be due to taphonomic displacement. The ventral
edge is thickened for articulation with the quadrate.
Quadrate. The posterolateral portion of the quad-
rate is exposed in both MHH 9 and in GPIT 1491/4
(Figure 2A, 2C). The quadrate is laterally concave.

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
8
The ventral articular end is thickened, and a small
occipital lamella is present.
Braincase
Basioccipital. The basioccipital is not well-pre-
served in the lectotype. It is best-exposed in SMNS
80226 and GPIT/RE/12905 in ventral view (Figure
2D-2E). It has an extensive extracondylar area
(ECA), with the portion ventral to the condyle being
wider than the lateral ECA. The ventral extracondy-
lar area is anteromedially concave, with small lat-
eral tubers. The condyle itself bears a notochordal
pit and is clearly offset from the extracondylar area.
Opisthotic. The right opisthotic is preserved in
SMNS 80226 (Figure 2D-2E), in what is interpreted
as anterior view. The medial edge bears a notch
interpreted as the vagus foramen. The paroccipital
process is short. The anterior surface of the opist-
hotic ventral to the paroccipital process is concave,
clearly setting off the process.
Stapes. An element thought to be the left stapes is
preserved in SMNS 80226 (Figure 2D). The lateral
shaft is slender, and the quadrate articulation is not
expanded. The ventral surface of the shaft is more
concave than the dorsal surface. The medial head
is robust.
Exoccipitals. Exoccipitals are preserved in SMNS
51552 as well as in the lectotype (Figure 2A-2B).
These are short, squat elements forming the lateral
edges of the foramen magnum. The medial edge is
concave. The number of foramina cannot be
assessed with confidence.
Prootic, supraoccipital, parabasisphenoid.
None of these elements could be identified with
confidence in the specimens determined to be
diagnostic at the specific level.
Palate
The palate of H. typicus is best-exposed in
SMNS 51552 (Figure 2B; see also Maisch, 1998a:
fig. 3).
Pterygoid. The pterygoid is preserved in ventral
view. The quadrate ramus is preserved posteriorly
and is offset from the palatal ramus by a pro-
nounced constriction. The lateral process of the
quadrate ramus is more slender than the medial
process. The palatal ramus bears a robust postpal-
atine process.
Palatine. The palatine is present in SMNS 51552;
however, due to poor preparation little can be said
about either its anatomy or position.
Vom er. The vomer could not be identified in the
specimens determined to be diagnostic at the spe-
cific level.
Mandible
A small overbite is consistently present (Fig-
ure 2A, 2C-2D, 2G); this does not appear to
become more pronounced in larger specimens.
The lower jaw is bowed ventral to the orbit.
The dentaries are fine and pointed anteriorly,
and make up approximately 45% of the length of
the mandibular symphysis (Figure 2D, 2G). In lat-
eral view, the dentary fossa is well-developed and
deep, but disappears towards the anteriormost tip
of the mandible (Figure 2A-2B). Aulacodont tooth
implantation is seen throughout the dentary, with
the alveolar groove narrowing significantly towards
the anterior tip (Figure 2C).
The splenials form the medial surface of the
mandible and a substantial portion of the mandibu-
lar symphysis. They are most robust at the poste-
riormost symphysis, thinning rapidly anteriorly in
ventral view (Figure 2B, 2D). Posteriorly, they also
attenuate in ventral view, but more slowly. At their
posterior ends, the splenials are concealed in ven-
tral view in articulated specimens by the medial
curvature of the angular, which forms a shelf.
The posterior lateral lower jaw is made up of
the surangular and angular. The lateral exposure of
the former is much greater than that of the latter.
The angular forms the ventral edge of the lower
jaw, extending from the retroarticular process pos-
teriorly to approximately the level of the external
narial opening. The surangular extends further
anteriorly than the angular. Ventral to the orbit, the
surangular forms a well-developed surangular
fossa. A strong ridge and ventral depression is
developed on the lateral surangular contribution to
the retroarticular process, presumably indicating a
point of muscle attachment.
Prearticular. The prearticular is preserved in
SMNS 80226, forming a fine splint of bone in ven-
tral view posterior to and medially overlapped by
the splenial.
Articular. The articular is not well-exposed in any
of the diagnostic material.
Dentition. The teeth are small and acutely pointed,
with the crowns typically showing some lingual cur-
vature. The enamel is smooth (Figure 2F, 2G).
Crown height decreases notably towards the ante-
rior tips of the jaws: in MHH 9, for instance, mid-
premaxillary tooth crowns are approximately 4.5
mm in height, whereas the anteriormost dentary
crowns are approximately 2 mm in height. The
tooth roots show strong apicobasal ridges indica-
tive of plicidentine; large quantities of cellular
cementum appear to be absent.

PALAEO-ELECTRONICA.ORG
9
Sclerotic ring. The sclerotic ring in the GPIT 1491/
4 preserves approximately 16–17 ossicles (poor
preservation makes an exact count impossible); 17
ossicles are also preserved in SMNS 51552 and
GPIT/RE/12905. In all three specimens, the scle-
rotic ring appears to fill the orbit, although tapho-
nomic breakage and distortion are moderate to
severe in all skulls (least so in GPIT/RE/12905).
Hyoid apparatus. Paired ceratobranchials are
ossified but often compressed, making it difficult to
assess morphology. Shape differs widely between
specimens, with the ceratobranchials being later-
ally concave in SMNS 51552 (Figure 2B) and later-
ally convex in SMNS 80226 (Figure 2D). An
ossified hyoid corpus is present in SMNS 51552
(Figure 2B).
Postcranium
Vertebral column. 45–46 presacral vertebrae, 81
preflexural vertebrae, ~3 apical vertebrae, and >55
postflexural vertebrae are preserved in the lecto-
type, becoming very small towards the end of the
caudal fin (Figure 1A). There is some uncertainty in
presacral count because the last vertebra with
unfused di- and parapophyses is posterior to the
position of the pelvic girdle. The atlas and axis are
preserved in SMNS 80226 and are exposed in lat-
eral view (Figure 4B). They are completely fused,
with a suture persisting on the lateroventral sur-
face. The remaining presacral centra are round in
articular view and are deeply amphicoelous. Cervi-
cal centra are small, and dimensions increase pos-
teriorly. Separate di- and parapophyses are
present in all dorsal vertebrae. Apophyses begin to
shift to a mid-centrum position anterior to the tail
bend. Apophyses are absent in the apical centra
and all postflexural vertebrae. The vertebral col-
umn is gently curved along its length, with the
points of inflection located in the anterior dorsal
region and mid-preflexural region.
FIGURE 4. Postcranial morphology of Hauffiopteryx typicus. A, anterior neural spines of the lectotype GPIT 1491/4,
note the broad axial neural spine of the same height as the neural spine of C3 but twice as wide. B, Fused atlas-axis
complex (SMNS 80226); C, gastralia in the mid-dorsal region of SMNS 80226, the arrow indicates the boomerang-
shaped medial element (see also inset); D, reconstruction of Hauffiopteryx typicus; the shape and position of the dor-
sal and caudal fins are based on the lectotype. Anterior is to the left in all parts. Scale bars in cm (parts B, C). Abbre-
viations: at-ax, atlas-axis complex; ns2, neural spine (axis).

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
10
In the lectotype, the axial neural spine is much
broader than more posterior neural spines at its
base, but tapers dorsally (Figure 4A). A substantial
facet for the atlantal neural spine is preserved on
its anterolateral surface. The atlantal spine itself is
not preserved. The anterior dorsal neural spines
are rectangular, but become broader and rounded
in the posterior 2/3 of the vertebral column (Figures
1A, 4D). Posterior to the pelvic girdle, neural
spines become T-shaped, and lose articulation with
each other. “Extra-neural processes” (sensu
McGowan, 1992), as previously described in
Stenopterygius, are present ventral to the posterior
end of the dorsal fin and also on several more
anterior vertebrae. Although positioned dorsal to
the ossified neural spines, these lack any visible
connection with the underlying skeletal tissues.
Ribs and gastralia. The cervical ribs are some-
what bicapitate, but the tuberculum and capitulum
are less deeply separated than in the dorsal ribs
(e.g., Figure 4A, 4C). Cervical and dorsal ribs are
deeply grooved on the anterior and posterior sur-
faces. Caudal ribs are small, holocephalous, and
paddle-like. Posterior to the apical vertebrae, ribs
are absent – the presence of extensive soft-tissue
preservation suggests that this is not an artefact.
Chevrons are absent throughout the caudal skele-
ton.
Gastralia are relatively robust. They are long
and thin, tapering at either end. There are two gas-
tralial elements per side. In SMNS 80226, gastralia
from the right and left sides are fused, forming a
single dorso-ventrally flattened and slightly antero-
posteriorly expanded boomerang-shaped bone
along the midline (Figure 4C). However, this speci-
men also shows signs of callus development on
many gastralia (Pardo-Pérez et al., 2019); it is
unclear whether the formation of a median element
may have been caused by trauma rather than rep-
resenting normal morphology.
Body outline. The dorsal and caudal fins are pre-
served in the lectotype (Figure 1A). The dorsal fin
is triangular in outline, located in the posterior half
of the dorsal region and terminating anterior to the
pelvic girdle. The caudal fin is semi-lunate in out-
line, and is symmetrical, with a very high aspect
ratio and a strongly concave posterior edge. How-
ever, the degree to which preparation may have
enhanced this shape is uncertain. The vertebral
column extends into the distalmost tip of the ventral
lobe.
Pectoral girdle and forelimb. The interclavicle is
T-shaped, with the transverse bar being longer
than the posterior stem. The posterior edge of the
transverse bar is medially broader than at its lateral
ends (Figure 5A). The clavicles are wing-like,
FIGURE 5. Hauffiopteryx typicus, pectoral girdle, and forelimb. A, pectoral girdle and humerus in ventral view (SMNS
80226); B, left forelimb in dorsal view (lectotype GPIT 1491/4); C, coracoids and left forelimb in ventral view (SMNS
51552). Scale bars in cm (parts A, C). Abbreviations: 2–4, distal carpals; cl, clavicle; co (r/l), right and left coracoids; H,
humerus; i, intermedium; ic, interclavicle; pi, pisiform; R, radius; re, radiale; sc, scapula; U, ulna; ue, ulnare; v, metacar-
pal V.

PALAEO-ELECTRONICA.ORG
11
tapering laterally, and medially broad (Figure 5A,
5C). The coracoids are large, anteroposteriorly lon-
ger than proximodistally wide (Figure 5A, 5C). A
small anterior notch is present. The scapular facet
is much smaller than the glenoid contribution. A
medial facet for the scapula appears to be absent.
The scapula itself is divided into a medial blade
and a lateral shaft (Figure 5A, 5B). The medial
blade is anteriorly expanded, but a well-developed
acromion process is absent. The coracoid facet is
smaller than the glenoid contribution.
The humerus is relatively elongate, with the
distal end greatly expanded relative to the proximal
end (Figure 5). A well-developed humeral head is
present only in the lectotype (Figure 5B); in all of
the referred specimens the proximal humerus is
rather flattened. The lectotype is the only specimen
in which the humerus is exposed in dorsal view;
unfortunately it is also the most strongly com-
pressed specimen. The dorsal process is small, if
present. The deltopectoral crest is robust, located
close to the anterior edge and extending over more
than half of the total length of the humerus (Figure
5A, 5C). The distal humerus bears a flattened,
anteriorly directed facet on its leading edge (“tuber-
cle” of Moon, 2017). Two distal facets are present,
for articulation with the radius and ulna. The ulnar
facet is larger than the radial facet.
All referred specimens show a similar forelimb
configuration, in which the radius, radiale, distal
carpal 2, and metacarpal II bear notches on their
anterior surfaces (Figure 5B, 5C). In most speci-
mens, the first phalanx of digit II is also notched
anteriorly. The radius articulates posteriorly with
the ulna, and distally with the radiale and interme-
dium. The ulna articulates distally with the interme-
dium and ulnare. A small pisiform posterior to the
ulnare is present only in the lectotype (Figure 5B).
The paddle is four digits wide; in the lectotype, a
series of very small accessory ossicles lies poste-
rior to digit V. The posterior two digits (IV and V)
are the longest, with ~10 phalanges. Proximal limb
elements are polygonal and tightly packed,
whereas more distal elements are rounded and
widely spaced. Based on the preserved soft tissue
outline, the flipper was elongate and tapering, with
digit II positioned close to the anterior edge.
Pelvic girdle and hind limb. The ilium is not well-
preserved in any of the referred specimens. In
SMNS 80226, the element inferred to be the ilium
is straight, shorter than the ischium and pubis (Fig-
ure 6A). The pubis is slender, being straight medi-
ally and posteriorly curving laterally to fuse with the
ischium. Its medial end appears to be medially flat-
tened. The ischium is the largest element in the
pelvic girdle. It is thickened laterally and is triangu-
lar in cross-section, with a flat anterior surface. The
medial end is also slightly anteroposteriorly
expanded, and is gently rounded.
The femur is wider distally than proximally.
The proximal end is strongly convex. The dorsal
process is pronounced and more rounded (Figure
6B-6D). The ventral process is narrower, and
extends further distally than the dorsal process
(Figure 6A). There are two distal facets, for articu-
lation with the tibia and fibula. The tibial facet is
smaller than the fibular facet.
The hind fins are short and rounded (Figure
6B-6E). There are three elements in the zeugopo-
dial row: the tibia, fibula, and a large pisiform that
appears to give rise to a postaxial digit (in the
sense that all elements in the digit are ossified and
decrease in size from proximal to distal). The tibia
is smaller than the fibula. The tibia and next three
distal elements are notched anteriorly. The astrag-
alus is positioned between the distal tibia and fib-
ula. There are four digits in the metatarsal row,
assuming that the posterior digit discussed above
can be homologized with the ‘true’ digits. As dis-
cussed by Maisch (2008), the digits converge dis-
tally and so are of equal length. There are only
approximately 4-5 phalanges per digit.
Hauffiopteryx altera sp. nov. Figures 7-8
v. 2005 Eurhinosaurus longirostris (Mantell, 1851):
Jäger, p. 29, fig. 23.
Holotype. Holotype and only referred specimen
FWD-129; a skull and partial postcranium pre-
served in a calcareous concretion (Figures 7-8;
see Table 1 for selected measurements). The
bones on the right side of the skull remain in articu-
lation; those on the left side of the skull have suf-
fered some taphonomic displacement.
Etymology. The specific epithet is derived from
the Latin altera, which means different from/other
and refers to the anatomical divergence from the
type species, H. typicus.
Geographical distribution. Dotternhausen-Dor-
mettingen, Baden-Württemberg, Germany.
Stratigraphic distribution. Posidonienschiefer
Formation, lower Toarcian, serpentinum Zone,
exaratum Subzone (SWGB: bed εII4/5).
Diagnosis. Hauffiopteryx altera differs from H typi-
cus in: deepest lateral exposure of the maxilla
located posterior rather than ventral to the external
narial opening; broad, triangular lacrimal excluded
from the external narial opening by the descending
process of the prefrontal; nasals extending further
posteriorly on dorsal skull roof; dorsal exposure of

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
12
prefrontal substantially greater than that of post-
frontal.
DESCRIPTION
Skull
Premaxilla. The premaxilla has been broken and
deformed anteriorly (Figure 7). Posteriorly, it is nar-
row and straight with a deep premaxillary fossa. A
supranarial process is absent. The posterior tip of
the premaxilla overlaps the maxilla almost to the
midpoint and forms the anteroventral edge of the
external nares.
Maxilla. The maxilla has a small contact with the
ventral edge of the external narial opening, and
extends less than one narial length anterior to the
nares (Figure 7C-7D). It is deeper posteriorly than
anteriorly. Its deepest point in lateral view contacts
the anteroventral tip of the prefrontal at the poste-
rior edge of the narial opening (Figure 7C). The
ventral edge of the maxilla is long and straight and
posteriorly extends only to the anterior edge of the
FIGURE 6. Hauffiopteryx typicus, pelvic girdle and hind limb. A, proximal left femur and pelvic girdle (SMNS 80226).
B, pelvic girdle and hind limbs in dorsal view (lectotype GPIT 1491/4); C–D, interpretive drawings of hind limbs of
same. E, hind limb of SMNS 51552. Abbreviations: 2–4, distal tarsals; a, astragalus; c, calcaneum; F, femur; Fi, fibula;
il, ilium; is, ischium; pi, pisiform; pb, pubis; Ti, tibia; v?, putative metatarsal V; note the homology issues regarding
both digit V and distal tarsal 2 in Hauffiopteryx and many other parvipelvians.

PALAEO-ELECTRONICA.ORG
13
FIGURE 7. Hauffiopteryx altera, sp. nov., holotype FWD-129. A, B, right and left lateral views; C, D, interpretation of
the cranial sutures in lateral view; E, F, ventral view of skull with interpretation; G, H, dorsal view of skull with interpre-
tation. Abbreviations: an, angular; de, dentary; en, external narial opening; f, frontal; j, jugal; lac, lacrimal; mx, maxilla;
n, nasal; ns2, neural spine (axis); pa, parietal; par, parietal ridge; pf, prefrontal; pm, premaxilla; po, postorbital; pof,
postfrontal; qj, quadratojugal; sa, surangular; scr, sclerotic ring; sp, splenial; st, supratemporal.

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
14
orbit on the right-hand side, being overlapped dor-
sally by the jugal; on the left the suborbital process
is exposed in lateral view and is very long, extend-
ing to the orbital midpoint.
Nasal and external narial opening. The external
narial opening is 25 mm long (right-hand side). It is
simple in shape, with a small posterodorsal notch
(Figure 7C). In lateral view, the dorsal surface of
the nasal has a weak dorsal inflection anterior to
the orbit. The ventral edge of the nasal is deflected
ventrally at the level of the external narial opening,
and the nasal forms a small ventrolateral shelf dor-
sal to the posterior narial opening. The nasals are
relatively narrow anteriorly, but become broader at
FIGURE 8. Hauffiopteryx altera, sp. nov., holotype FWD-129. A, left dorsal temporal region, illustrating the palmate
morphology of the supratemporal; B, premaxillary and dentary teeth illustrating the thin, smooth enamel; scale bar is
in mm; C, anterior neural arches, note the size and shape differentiation between the neural spines of the atlas, axis,
and more posterior vertebrae; D, proximal right forelimb in dorsal view; E, pectoral girdle in external view. Abbrevia-
tions: cl, clavicle; co (r)/co (l), right and left coracoids; H, humerus; i, intermedium; ic, interclavicle; ns1, neural spine
(atlas); ns2, neural spine (axis); ns3, neural spine (C3); pa, parietal; pof, postfrontal; R, radius; re, radiale; sc, scapula;
st, supratemporal; st.a, medial process of the anterior ramus of the supratemporal; st.m, medial ramus of the supra-
temporal; U, ulna; ue, ulnare; utf, supratemporal fenestra.

PALAEO-ELECTRONICA.ORG
15
the level of the orbit, and are relatively limited in
posterior extent. In dorsal view, the right and left
nasals diverge posteriorly, creating a V-shaped
contact with the frontals. An internasal depression
is present, and an internasal foramen is possibly
present (Figure 7G-7H); the dorsal surface of each
nasal is strongly convex. The nasal contacts the
frontal posteriorly and prefrontal laterally.
Lacrimal. The lacrimal is excluded from the exter-
nal narial opening in lateral view by the prefrontal
(Figure 7C-7D). The lacrimal is a blocky element,
narrowing anteriorly with a scalene triangle shape
in lateral view; it contacts the prefrontal dorsally
and the jugal ventrally. The suborbital process is
short. The lacrimal does not contact the maxilla but
converges with the jugal and the prefrontal anterior
to the orbit and posterior to the narial opening. The
lacrimal is anteroposteriorly longest at the level of
the sclerotic aperture. The anterior tip of the lacri-
mal appears to be laterally deflected relative to the
posterior part of the element, and the portion mak-
ing up the circumorbital area is more strongly
curved than the ventral edge of the element.
Jugal. The jugal is deeply bowed ventral to the
orbit. It tapers anteriorly between the lacrimal and
the maxilla, extending past the anterior edge of the
circumorbital area. Posteriorly, the jugal is over-
lapped by the postorbital. The posterior ramus of
the jugal is offset approximately 120º from the ven-
tral one, being wider and shorter with a flat external
surface. The dorsal margin is evenly curved,
whereas the ventral one forms a small projection at
the posteroventral orbit (Figure 7C-7D).
Prefrontal. The prefrontal is a large element form-
ing the anterodorsal orbital rim, with an anterior
process reaching the external narial opening and
forming its entire posterior edge. The prefrontal
contacts the anterior tip of the jugal (Figure 7C-
7D). The body of the prefrontal is massive, being
as broad in dorsal view as the nasal (Figure 7G-
7H). In lateral view, the anterior portion forming the
orbital rim tapers ventrally and is considerably thin-
ner than the posterior portion. Posterodorsally, the
prefrontal contacts the postfrontal, parietal, and
frontal (medially).
Frontal. The frontals are small and elongate, and
are dorsally convex. They enclose the parietal fora-
men medially (Figure 7G-7H). The frontal is over-
lapped by the nasal (anteriorly), prefrontal
(laterally), and parietal (posteriorly).
Parietal. The parietal has an irregular external sur-
face (Figures 7G-7H, 8A). There is a depression
between the medial supratemporal fenestra and
interparietal suture, possibly corresponding to the
area lateral to the sagittal eminence. The parietal
shelf is large and oriented dorsally. The parietal
ridge is weakly developed. Posterolaterally, the
parietal has a small process, which contacts the
supratemporal posteriorly. The parietal contacts
the prefrontal (anteriorly), postfrontal (laterally),
and frontal (anterolaterally).
Postfrontal. The postfrontal is anteroposteriorly
elongate and has an anteromedial depression in
dorsal view (Figures 7G-7H, 8A). Its posteromedial
edge encloses the supratemporal fenestra and is
overlapped by the supratemporal. The postfrontal
becomes narrower anteriorly until it forms a point
that overlaps the prefrontal anteriorly. In lateral
view, the postfrontal is slightly arched and forms
the dorsolateral edge of the posterior skull. The
postfrontal extends as far anteriorly as the anterior
parietal but is narrower than the latter, and extends
anteriorly to the orbital midpoint (Figure 7C).
Postorbital. The postorbital forms the posterior
edge of the orbit (Figure 7C). A small dorsal
lamella appears to be present. In lateral view, the
postorbital is wider than the jugal, but still narrow in
relation to its height. The ventral postorbital over-
laps the jugal, and is excluded from the postero-
ventral edge of the orbit by the latter. The dorsal
postorbital is overlapped by the postfrontal. The
dorsal and ventral ends of the postorbital are
tapered, forming a semilunate shape.
TABLE 1. Hauffiopteryx altera sp. nov., selected mea-
surements (in mm) of FWD-129 (holotype).
Measurement
Total preserved length 590
Lower jaw 280 (preserved
length)
Maxilla 92
Posterior lower jaw to
symphysis
200
Length Width
Orbit (right) 96 85 (height)
Sclerotic aperture 35.5 38.5 (height)
Sclerotic ring 88 79 (height)
Humerus (right) 46 32 (proximal)
41 (distal)
Radius (right) 26 25
Ulna (right) 26 25
Coracoid (right) 59 50
Scapula (right) 71 32 (proximal)
23 (distal)

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
16
Supratemporal. The supratemporal is posteriorly
broad and slightly convex dorsally (Figures 7G-7H,
8A). A long anterior ramus excludes the postfrontal
from the lateral edge of the supratemporal fenes-
tra. The supratemporal is anteroposteriorly shorter
than mediolaterally broad. A descending ramus is
present but not clearly exposed. The supratempo-
ral bears four ridges radiating from the posterolat-
eral corner (Figure 8A); we use the term ‘palmate’
to refer to this morphology.
Quadratojugal. The quadratojugal is small, trian-
gular, and articulates along its entire anterior edge
with the postorbital (Figure 7C).
Orbit. The sclerotic ring consists of 16 plates. It is
88 mm long and 79 mm high; the sclerotic aperture
is 38.5 mm high and 35.5 mm long and is elliptical
in shape. The orbit is 96 mm long and 85 mm high
and is teardrop-shaped in lateral view when the cir-
cumorbital area is also considered. The orbit is bor-
dered by the prefrontal, postfrontal, postorbital,
jugal, and lacrimal (Figure 7C-7D).
Quadrate and Palate
There is an element covered by the postor-
bital in right lateral view, which may be the quad-
rate based on position and shape.
The palate is not exposed.
Mandible
Dentary. The dentary is a robust element that
tapers anteriorly (Figure 7C-7D). The anterior tip is
missing. The posterior end forms a thin point, artic-
ulating ventrally with the surangular at the level of
the anterior orbit. The dentary becomes progres-
sively deeper ventral to the external narial opening
until it makes up the entire lateral surface of the
lower jaw. The dentary is slightly convex in lateral
view along the entire occlusal edge. The dentary
fossa is present along its lateral surface.
Angular. The angular is short and does not extend
as far anteriorly as the surangular in lateral view
(Figure 7D). In ventral view, the posterior end of
the angular is slightly expanded with rounded
edges, while the anterior end tapers to a sharp
point, and disappears from ventral view at approxi-
mately the level of the maxilla, just posterior to the
symphysis (Figure 7E-7F). The ventral edge of the
angular is not strongly curved in lateral view. How-
ever, the lower jaw appears slightly bowed ventral
to the orbit (Figure 7C-7D).
Splenial. Posteriorly, the splenial contacts the
medial surface of the angular, becoming broader in
ventral view as the angular thins (Figure 7E-7F).
The splenial is thin and convex in ventral view. The
posterior end is elongated and pointed. The ante-
rior end is not preserved. The broadest point of the
splenial in ventral view occurs at the posterior end
of the mandibular symphysis.
Surangular. The surangular is an elongate and
large element that forms a significant part of the
posterior end of the lower jaw (Figure 7C-7D). It is
strongly curved ventral to the orbit. The posterior
end is broad and ovate in lateral view, with a sinu-
soidal dorsal margin, formed in part by a small cor-
onoid process. The anterior contact with the
dentary is elongate, almost one-third of the length
of the surangular in lateral view. The surangular
fossa is deep. Anteriorly, the surangular is
excluded in ventral view by the splenial and the
dentary at approximately the same point as the
mandibular symphysis (Figure 7E-7F).
Prearticular. The prearticular is only preserved on
the right side. It is laterally compressed and elon-
gate, positioned medial to the angular and lateral
to the posteriormost splenial.
Dentition. The teeth are small and acutely pointed,
with smooth, thin enamel lacking macroscopic
ornamentation (Figure 8B). There is no pro-
nounced constriction between the crown and root.
The roots are not well-enough preserved to assess
the presence or absence of apicobasal ridges,
however, the root is smooth immediately basal to
the crown. Crown height is 4 mm at the midpoint of
the dentary. The teeth extend as far posteriorly as
the anterior orbital margin.
Hyoid apparatus. The left ceratobranchial is pre-
served (Figure 7E-7F). An element in the position
of the right hyoid is of questionable identity.
Postcranial Axial Skeleton
The atlas-axis complex is not visible. The third
cervical centrum (C3) is the first vertebral centrum
exposed on the right side. The right and left sides
of the atlantal neural spine are unfused, and the
atlantal neural spine is much smaller and shorter
than the axial neural spine (Figure 8C). The axial
neural spine is twice as wide as that of C3 and
more posterior dorsal neural spines, with an
anterolateral facet for articulation with the atlantal
spine (Figure 7D). Postzygapophyses appear to be
paired until at least C7. Anterior dorsal centra bear
paired apophyses. Vertebrae are taphonomically
compressed.
The anteriormost dorsal ribs are bicapitate,
but the tuberculum and capitulum are less clearly
separated than in more posterior ribs (Figure 7B).
Ribs bear an anterodorsal groove; this groove
does not extend to the distal half of the rib. Some

PALAEO-ELECTRONICA.ORG
17
partial gastralia are preserved immediately poste-
rior to the forelimb (Figure 7A).
Pectoral Girdle
Clavicle. The clavicle is wing-like, broadening
medially and concave posteriorly with a thin dorsal
process. It is twisted ventrally from the middle of
the axis in such a way that the lateral ramus is off-
set approximately 120º from the medial one (Fig-
ure 8E). The medial ramus is more robust, broad,
and convex than the lateral ramus. Whereas the
medial ramus is slightly curved, the lateral one is
flattened on both its dorsal and ventral surfaces.
Scapula. The anterior blade is concave in external
view. An anterior expansion is present (Figure 8E).
The coracoid facet is smaller than the glenoid
facet. The posterior shaft of the scapula is dorsally
straight and mediolaterally compressed. The pos-
terior shaft is curved ventrally and slightly flared at
its distal end. The ventral edge is proximodistally
shorter than the dorsal edge.
Coracoid. The coracoid is saddle-shaped in exter-
nal view, with the glenoid and scapular facets thick-
ened and projecting ventrally. The coracoid is more
or less equidimensional and rounded, and is
almost as long as the median stem of the interclav-
icle (Figure 8E). An anterior notch is present but
the posterior notch is reduced or absent. The gle-
noid facet is slightly rugose and much larger than
the scapular facet. The intercoracoid facet is
extremely reduced.
Interclavicle. The interclavicle is ‘T’-shaped. The
posterior stem is approximately as long as the
transverse bar. The transverse bar is relatively
wide and convex in external view (Figure 8E). In
anterior view, the transverse bar is broad and
tapers laterally towards the tips.
Forefin
Humerus. The distal end of the humerus is wider
than the proximal end, but not significantly so
(Table 1; Figure 8D), and a mid-shaft constriction is
present. The proximal anterior surface of the
humerus is flattened. The dorsal process lies
towards the anterior edge and is relatively small,
extending less than half the length of the humeral
shaft. In anterior view, it can be seen that the delto-
pectoral crest extends further distally than the dor-
sal process. The ulnar facet is longer than the
radial facet. The anterior distal edge is slightly
squared off, forming a prominent leading edge
facet. The ulnar facet is straighter in dorsal view,
whereas the radial facet is more concave.
Distal limb elements. The ulna and radius are in
broad contact. The radius is notched anteriorly, and
bears distal articular facets for the radiale and
intermedium; the facet for the former is longer than
that of the latter. The ulna is pentagonal in outline,
with distal facets for the intermedium and ulnare.
The pisiform is absent in FWD-129. The interme-
dium is pentagonal in outline, and forms a large
contact with distal carpal 3. The ulnare is very
small and proximodistally short, smaller than the
intermedium.
Hauffiopteryx sp., Figure 9
SMNS 81367, SMNS 80225, SMNS 81962,
and SMNS 81965 are referable to Hauffiopteryx
sp., but the diagnostic portions of the skull are
either not exposed or are damaged (Figure 9).
SMNS 81367 (Figure 9A) is a small individual
with the skull preserved in dorsolateral and the
postcranium preserved in ventrolateral views. The
specimen is clearly referable to Hauffiopteryx
based on the small, round supratemporal fenes-
trae, the palmate morphology of the supratempo-
ral, and the location of the parietal foramen anterior
to the anterior edge of the supratemporal fenestra.
Extensive reconstruction in the narial region pre-
vents an accurate assessment of morphology and
thus specific referral. This specimen was figured as
H. typicus by Pardo-Pérez et al. (2019).
SMNS 80225 (Figure 9B) is a poorly pre-
served specimen prepared in ventrolateral view.
The skull has been partially reconstructed. This
specimen is referred to Hauffiopteryx sp. based on
the number and posterior extent of the gastralia.
Fragmentary pelvic elements suggest the absence
of a robust ischiopubis, also consistent with Hauffi-
opteryx. This specimen was considered to be refer-
able to H. typicus by Maisch (2008).
SMNS 81962 (Figure 9C) is preserved in ven-
tral view. The anterior rostrum has been recon-
structed. This specimen is referred to Hauffiopteryx
based on the reniform outline of the quadrate in lat-
eral view, palmate supratemporal, and the hind
limb with digits converging distally.
SMNS 81965 (Figure 9D) is also preserved in
ventral view; the rostrum has been reconstructed.
This specimen is considered to be referable to
Hauffiopteryx based on the extensive development
of gastralia, and the medially unfused ischium and
pubis. An ossified hyoid corpus is present, a fea-
ture thusfar only observed in Hauffiopteryx among
ichthyosaurs (Motani et al. 2013). SMNS 81965
was considered to be referable to H. typicus by
Maisch (2008).

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
18
PHYLOGENETIC ANALYSIS
In order to test the relationship between mate-
rial referred to Haffiopteryx typicus from the UK
and Germany, Hauffiopteryx altera sp. nov., NMO
26575, and Leptonectes tenuirostris, we scored
these as five separate OTUs in a version of the
Moon (2017) Ichthyosauria matrix modified based
on Maxwell et al. (2019). The Hauffiopteryx mate-
rial from England was scored from the literature
(Caine and Benton, 2011; Marek et al., 2015);
NMO 26575 was scored based on personal obser-
vation (EM) and Maisch and Reisdorf (2006). In
addition, we added the taxa Protoichthyosaurus
prostaxalis and P. applebyi, scored based on
Lomax et al. (2017, 2019a, 2019b) and Lomax and
Massare (2018). Additional character and scoring
changes are outlined in Appendices 2–3; the nexus
FIGURE 9. Hauffiopteryx sp. A, SMNS 81367; B, SMNS 80225; C, SMNS 81962; D, SMNS 81965. Photos © SMNS /
M. Wahler.

PALAEO-ELECTRONICA.ORG
19
file is provided in Appendix 4. We analyzed the
data using maximum parsimony implemented in
TNT v. 1.5 (Goloboff and Catalano, 2016) with a
New Technology search (100 iterations of the
ratchet algorithm, minimum length found 100
times) (Figure 10). Following parsimony analysis,
the resulting MPTs were analyzed using the Iter-
PCR script (Pol and Escapa, 2009), and 12 taxa
causing instability were pruned from the strict con-
sensus tree. Among neoichthyosaurian taxa, this
resulted in Malawania anachronus, Temnodonto-
saurus eurycephalus, Pervushovisaurus ban-
novkensis, P. campylodon, and Simbirskiasaurus
birjukovi being pruned (see Appendix 2 for com-
plete list). A Bayesian analysis (Figure 11) was
executed in Mr. Bayes. Search settings and taxon
selection are outlined in Maxwell et al. (2019).
Both Bayesian and parsimony analyses sup-
port referral of NMO 26575 and FWD-129 to the
genus Hauffiopteryx, distinct from all three species
of Leptonectes (Figures 10-11). Moreover, material
referred to Hauffiopteryx typicus from Germany
and England formed a monophyletic group. We
consider scoring differences between these H. typ-
icus OTUs to be caused by differences in taphon-
omy (three-dimensional preservation vs. strong
lateral compression), variation in the quality of
preservation and preparation, and ontogeny, with
the British material thought to represent juvenile
individuals. Hauffiopteryx formed a sister group to
Stenopterygius + Ophthalmosauridae in parsimony
analysis (Figure 10); its position relative to
Stenopterygius spp. and Leptonectes spp. was
unresolved in Bayesian analysis (Figure 11).
DISCUSSION
Comparison of Hauffiopteryx to Other Early
Jurassic Ichthyosaurs
Hauffiopteryx differs from all coeval Toarcian
ichthyosaur genera in the extensive participation of
the prefrontal in the external narial opening. The
prefrontal is excluded in Temnodontosaurus trigo-
nodon, Stenopterygius (Maisch, 1998a); Suevole-
viathan (Maisch, 2001), Eurhinosaurus (SMNS
18648), as well as in Leptonectes (McGowan and
Motani, 2003). The nasals in Hauffiopteryx are
more extensively exposed dorsally anterior to the
external narial opening than the premaxillae, unlike
in Stenopterygius (e.g., Maxwell, 2012b). As in
Eurhinosaurus (e.g., SMNS 18648), the upper tem-
poral fenestrae are small and circular, the supra-
temporal is broad and palmate in morphology, and
the parietal shelf is horizontally oriented. As in
Temnodontosaurus trigonodon (Fraas, 1913), the
splenial plays a major role in the mandibular sym-
physis. The teeth of Hauffiopteryx are slender and
conical, with smooth enamel unlike in Suevolevia-
than, in which the enamel is rugose in texture
(Maxwell, 2018). In the postcranium, the gastralia
in Hauffiopteryx extend posteriorly at least as far as
the thirty-fifth vertebra. This is unique among Toar-
cian genera: gastralia are unknown in Temnodon-
tosaurus trigonodon and Suevoleviathan; in
Eurhinosaurus and Stenopterygius gastralia are
present in the anterior- to mid-dorsal region (Buch-
holtz, 2001). The rib tuberculum and capitulum in
the dorsal region are widely separated in Hauffiop-
teryx, as in Stenopterygius but unlike in Temnodon-
tosaurus trigonodon, Eurhinosaurus, and
Suevoleviathan (Maisch and Matzke, 2000). The
anterior scapula is expanded and a foramen
between the humerus, radius, and ulna is absent,
unlike in Temnodontosaurus trigonodon (e.g.,
SMNS 17560). The elements of the anterior digit in
both the fore- and hind limbs bear notches, and the
proximal limb elements are angular and tightly
interlocking, unlike in Suevoleviathan (Maisch,
1998b). The ischium and the pubis are thin and
styloidal, unlike in Temnodontosaurus, Suevolevia-
than, and Eurhinosaurus (Maisch and Matzke,
2000), but are widely separated medially, unlike in
Stenopterygius in which they are fused both medi-
ally and laterally (Maisch and Matzke, 2000).
Parsimony analysis resolved the position of
Hauffiopteryx as sister to Stenopterygius + Oph-
thalmosauridae (Figure 10). Although poor resolu-
tion outside this group increases ambiguity in
character reconstruction, this clade is supported by
a narrow, tapering anterior jugal, the basioccipital
contributing to the floor of the foramen magnum in
posterior view, a supraoccipital with parallel exoc-
cipital processes, a caudal region approximately
equal in length to the presacral vertebral column,
one complete postaxial digit supported by an
ulnare with two well-developed distal articular fac-
ets, polygonal metacarpals and phalanges, and lat-
eral fusion of the ischiopubis. The strongly grooved
ribs with broadly separated tuberculum and capitu-
lum in the mid-dorsal region are also different from
all leptonectids (Maisch and Matzke, 2000).
In the skull, greater similarities to leptonectids
are present – especially in the dermatocranium.
These include the thin rostrum with elongated
external narial opening, the small upper temporal
fenestra, the enlarged, palmate supratemporal, the
horizontally oriented parietal slope, and the slight
overbite. However, unexpected similarities with

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
20
Chacaicosaurus cayi
Ophthalmosauridae
Parvinatator wapitiensis
Barracudasauroides panxianensis
Contectopalatus atavus
Phalarodon callawayi
Phalarodon fraasi
Mixosaurus xindianensis
Mixosaurus cornalianus
Mixosaurus kuhnschneyderi
Toretocnemus californicus
Toretocnemus zitteli
Besanosaurus leptorhynchus
Cymbospondylus buchseri
Cymbospondylus petrinus
Pessopteryx nisseri
Shastasaurus liangae
Shastasaurus pacificus
Shastasaurus sikkaniensis
Californosaurus perrini
Phantomosaurus neubigi
Himalayasaurus tibetensis
Thalattoarchon saurophagis
Guizhouichthyosaurus tangae
Callawayia neoscapularis
Shonisaurus popularis
Hudsonelpidia brevirostris
Guizhouichthyosaurus wolonggangense
Macgowania janiceps
Ichthyosaurus breviceps
Ichthyosaurus communis
Ichthyosaurus larkini
Ichthyosaurus somersetensis
Ichthyosaurus anningae
Ichthyosaurus conybeari
Protoichthyosaurus prostaxalis
Protoichthyosaurus applebyi
Stenopterygius aaleniensis
Stenopterygius triscissus
Temnodontosaurus crassimanus
Suevoleviathan integer
Temnodontosaurus nuertingensis
Temnodontosaurus platyodon
Temnodontosaurus trigonodon
Hauffiopteryx altera sp. nov.
NMO 26575
Hauffiopteryx typicus (UK)
Hauffiopteryx typicus (Germany)
Leptonectes moorei
Leptonectes tenuirostris
Temnodontosaurus azerguensis
Eurhinosaurus longirostris
Wahlisaurus massarae
Excalibosaurus costini
Leptonectes solei
Stenopterygius uniter
Stenopterygius quadriscissus
22
33
2
2
2
Gulosaurus helmi
Ichthyosauria
3
3
3
2
3
3
2
FIGURE 10. Strict consensus of 158 most parsimonious trees of length 1663; taxa flagged by IterPCR as being unsta-
ble have been pruned from the figure. The arrow indicates OTUs included in the genus Hauffiopteryx. Bremer support
values greater than 1 are indicated to the left of the nodes.

PALAEO-ELECTRONICA.ORG
21
Ophthalmosauridae
Chacaicosaurus cayi
Stenopterygius aaleniensis
Stenopterygius triscissus
Stenopterygius quadriscissus
Stenopterygius uniter
Eurhinosaurus longirostris
Excalibosaurus costini
Leptonectes solei
Leptonectes moorei
Leptonectes tenuirostris
Temnodontosaurus azerguensis
Wahlisaurus massarae
Hauffiopteryx typicus (UK)
Hauffiopteryx typicus (Germany)
Hauffiopteryx altera sp. nov.
NMO 26575
Malawania anachronus
Ichthyosaurus anningae
Ichthyosaurus breviceps
Ichthyosaurus communis
Ichthyosaurus conybeari
Ichthyosaurus larkini
Ichthyosaurus somersetensis
Protoichthyosaurus prostaxalis
Protoicthyosaurus applebyi
Macgowania janiceps
Suevoleviathan integer
Temnodontosaurus crassimanus
Temnodontosaurus eurycephalus
Temnodontosaurus nuertingensis
Temnodontosaurus platyodon
Temnodontosaurus trigonodon
Barracudasauroides panxianensis
Phalarodon callawayi
Contectopalatus atavus
Mixosaurus cornalianus
Mixosaurus kuhnschneyderi
Phalarodon fraasi
Mixosaurus xindianensis
Besanosaurus leptorhynchus
Californosaurus perrini
Phantomosaurus neubigi
Callawayia neoscapularis
Cymbospondylus buchseri
Cymbospondylus nichollsi
Cymbospondylus petrinus
Guizhouichthyosaurus tangae
Guizhouichthyosaurus wolonggangense
Himalayasaurus tibetensis
Hudsonelpidia brevirostris
Mikadocephalus gracilirostris
Parvinatator wapitiensis
Pessopteryx nisseri
Qianichthyosaurus xingyiensis
Wimanius odontopalatus
Qianichthyosaurus zhoui
Quasianosteosaurus vikinghoegdai
Shastasaurus liangae
Shastasaurus sikkaniensis
Shastasaurus pacificus
Shonisaurus popularis
Thalattoarchon saurophagis
Toretocnemus zitteli
Toretocnemus californicus
Xinminosaurus catactes
96
79
83
68
92
90
94
61
75
92
98
95
64
59
6469
89
76
55
73 86
67
54
100 60
96
Ichthyosauria
55
50
50
53
60
54
FIGURE 11. 50% majority rule tree derived from Bayesian analysis. Clade credibility values indicated to the left of the
nodes. The arrow indicates OTUs included in the genus Hauffiopteryx.

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
22
Temnodontosaurus (e.g., SMNS 50000) are also
identified in the skull: the anteroposterior orienta-
tion and large size of the extracondylar area (ECA)
of the basioccipital rather than the ECA being dor-
soventrally oriented, such as that of Eurhinosaurus
(SMNS 18648) and to a lesser extent Leptonectes
tenuirostris and Wahlisaurus (Lomax and Massare,
2012; Lomax, 2016), and the extensive participa-
tion of the splenial in the mandibular symphysis
(see Fraas, 1913). These differences support an
independent derivation of a longirostrine morpho-
type in Leptonectidae and Hauffiopteryx, as argued
by Moon (2017), although unlike Moon we recover
T. azerguensis as a leptonectid in the Bayesian
analysis (Figure 11).
Maisch (2008) was of the opinion that Hauffi-
opteryx typicus was characterized by certain
unusual ontogenetic changes, namely: 1) strong
positive allometry of the antorbital rostrum relative
to the skull with increasing body size, and 2) strong
positive allometry of the skull relative to presacral
length. Unfortunately, the rostrum appears to have
been reconstructed/modified in most of the avail-
able specimens of H. typicus, with the exception of
GPIT 1491/4, GPIT/RE/12905, SMNS 80226, MHH
9, and BRSLI M1399 (see Table 2 for raw mea-
surements). Based on log-transformed data, the
antorbital rostrum appears to have grown with
weak positive allometry relative to the lower jaw
(slope = 1.15), and the lower jaw grew with strong
negative allometry relative to the presacral verte-
bral column, the humerus, and to a lesser extent,
the femur (as reported for e.g., Stenopterygius
quadriscissus and Ichthyosaurus communis:
McGowan, 1973). Thus, at present there is some
support for the view that antorbital rostrum of Hauf-
fiopteryx typicus showed a different allometric
growth pattern than Ichthyosaurus and Stenopte-
rygius, although there is enough variation present
that this pattern is not clearly apparent in the ratios
of individual specimens.
Ontogenetic Status of FWD-129 and Generic
Referral of Hauffiopteryx altera
FWD-129 shows multiple features consistent
with Hauffiopteryx from both the Posidonien-
schiefer Formation as well as from coeval localities
in England, but differs from Stenopterygius, the
most abundant and widespread ichthyosaur genus
during the Toarcian. Characters supporting the
referral of FWD-129 to Hauffiopteryx include partic-
ipation of the prefrontal in the posterior external
narial opening, small, round upper temporal fenes-
trae situated posterior to the pineal foramen, short
nasals that do not contact the parietals, and a fore-
fin with tightly interlocking, polygonal phalanges
with a notch on the elements of the leading edge
digit (Maisch, 2008; Caine and Benton, 2011). This
combination of features is consistent with Hauffiop-
teryx among all ichthyosaurian genera, and this
referral is also supported by both parsimony and
Bayesian phylogenetic analysis (Figures 10-11).
However, FWD-129 differs from H. typicus based
on some aspects of cranial anatomy.
TAB LE 2. Hauffiopteryx comparative measurements (mm).
* measured from photos in Cain and Benton (2011)
** measured from photo in Maisch (2008)
*** from Maisch and Reisdorf (2006)
Specimen/taxon
Approximate
presacral length
(without skull)
Lower jaw
(length)
Antorbital
rostrum
Humerus
(length)
Femur
(length)
FWD-129 (H. altera sp. nov.) -- >280 -- 46 --
GPIT 1491/4 (H. typicus) 620 380 ~216 57 35
GPIT/RE/12905 (H. typicus) -- 462 306 -- --
BRSLI M1399 (H. typicus) 590* 322 192* 47* 30*
SMNS 51552 (H. typicus) ~930 >520 >295 75 54
SMNS 80226 (H. typicus) ~879 440 258 59 40
MHH 9 (H. typicus) -- 460 282 68 ** --
NMO 26575 (H. typicus) -- 370-400 mm*** 247*** -- --
SMNS 81367 (Hauffiopteryx sp.) -- 385 -- 60 --
SMNS 80225 (Hauffiopteryx sp.) ~809 incomplete incomplete 53 30
SMNS 81962 (Hauffiopteryx sp.) -- -- -- -- 49
SMNS 81965 (Hauffiopteryx sp.) ~997 >280 -- 57 --

PALAEO-ELECTRONICA.ORG
23
Maisch (2008) considered individuals of Hauf-
fiopteryx typicus of less than 2.5 m total length to
be juveniles. Thus, using Maisch’s criterion, with a
total length of 193 cm (Table 2) GPIT 1491/4 would
be a juvenile; however, we suspect that the speci-
men is osteologically mature based on the convex
shape of the proximal humerus and closure of the
sutures between phalanges (Johnson, 1977).
Caine and Benton (2011) estimated total length in
BRLSI M1399 at ~150 cm (skull length = 322 mm;
humerus = 47 mm [from photo: Caine and Benton,
2011: text-fig. 9]); this specimen has been gener-
ally interpreted as a juvenile (Caine and Benton,
2011; Marek et al., 2015).
FWD-129 was initially considered to be a
juvenile of Eurhinosaurus longirostris, due to its
small size, large orbits, and small temporal fenes-
tra (Jäger, 2005). FWD-129 is approximately equal
in size to BRLSI M1399, with a lower jaw at least
280 mm in length and a humerus 46 mm in length
(Table 2). The proximal articular surface of the
humerus is flat, and the sutures between the limb
elements remain open, also strongly supporting a
juvenile attribution for this specimen. Relative pro-
portions of the skull to the postcranium (McGowan,
1973), proportions within the skull (especially per-
taining to the orbit/sclerotic ring: Fernández et al.,
2005), relative tooth size (Dick and Maxwell, 2015),
and notching of the anterior limb elements (Max-
well et al., 2014) are known to be ontogenetically
influenced in the closely related genus Stenopte-
rygius. However, the characteristics separating
FWD-129 from specimens referred to H. typicus,
Stenopterygius, and Eurhinosaurus are not
expected to vary ontogenetically. This is especially
apparent given that FWD-129 is of a similar onto-
genetic stage to BRLSI M1399 based on both
absolute size and limb ossification, but shows
numerous differences in cranial morphology.
Comparison of Hauffiopteryx altera with
Hauffiopteryx typicus
The lectotype of H. typicus (GPIT 1491/4)
from Holzmaden is severely crushed, whereas
FWD-129 is a lightly compressed three-dimen-
sional skeleton. Nevertheless, it is possible to iden-
tify ways in which the two skulls differ. In H. typicus,
the orbit is very large and round, creating a steep
inflection in the nasal in lateral view. In FWD-129,
the orbit is more elongate, and in lateral view the
nasals are less steeply inflected anterior to the
orbit than in H. typicus. SMNS 51552 and MHH 9
(Figure 2B, 2C) are much more similar in shape to
the lectotype of H. typicus (GPIT 1491/4; Figure
2A) than to FWD-129 (Figure 7C). Unlike in GPIT
1491/4, MHH 9, and SMNS 51552, the lacrimal of
FWD-129 does not separate the prefrontal from the
jugal, and is excluded from the external narial
opening. The lacrimal of FWD-129 is more robust
than in specimens referred to H. typicus. These dif-
ferences result in a relatively larger distance
between the anterior edge of the orbit and the nar-
ial opening in FWD-129 than in H. typicus. The
maxilla is overlapped dorsally by the lacrimal over
almost one third of the posterodorsal surface, and
the maxilla forms the ventral edge of much of the
external nares in the lectotype, MHH 9, and SMNS
51552. In FWD-129, it is the jugal rather than the
lacrimal that overlaps the maxilla posteriorly, and
the maxilla is almost entirely excluded from the
external narial opening in lateral view.
BRLSI M1399 has a shallower, more elon-
gated maxilla than FWD-129, but the maxilla of
FWD-129 has a greater contact with the ventral
surface of the premaxilla than that of BRLSI M
1399, with the premaxilla extending well past the
midpoint of the external nares in the former speci-
men. The maxilla of FWD-129 is slightly deeper
posteriorly, whereas in the English specimen the
maxilla is rather similar in depth along its entire
length. The maxilla of FWD-129 contacts the lacri-
mal and prefrontal posterodorsally, whereas in
BRLSI M1399 the maxilla contacts only the lacri-
mal. The lacrimal of BRLSI M1399 participates
posteriorly in the external narial opening (Marek et
al., 2015: fig. 1; Caine and Benton, 2011: fig. 9);
however, in FWD-129 it is excluded from the exter-
nal narial opening by the prefrontal. In dorsal view,
the prefrontal in FWD-129 is anteroventrally nar-
rower than that of BRLSI M1399. Also, the narial
ramus is more anteroposteriorly oblique in relation
to the oval orbit. The jugal extends much further
anteriorly in FWD-129 than in BRLSI M1399
(Caine and Benton, 2011: fig. 12; Marek et al.,
2015: fig. 1). The orbit is also rounder in BRLSI
M1399. These features are very similar to the set
of characters differentiating FWD-129 from H. typi-
cus, consistent with our interpretation of BRLSI
M1399 as referable to H. typicus.
Marek et al. (2015) cited the absence of root
striations, the absence of the narial process of the
maxilla, the presence of the temporal process of
the frontal, wing-like basipterygoid processes, the
absence of a ventral notch in the extracondylar
area of the basioccipital, and the rod-like ischium/
ischiopubis as differing between Hauffiopteryx and
BRLSI M1399. However, some of these conclu-
sions are the result of character scoring errors:

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
24
BRLSI M1399 has a ventral notch in the extracon-
dylar area of the basioccipital (Marek et al., 2015:
fig. 10a), and lacks participation of the frontal in the
supratemporal fenestra (i.e., processus temporalis
of the frontal absent, Marek et al., 2015: fig. 4a).
The only character listed that truly differs between
H. typicus and BRLSI M1399 is the absence of root
striations in the latter; however, Marek et al. (2015)
state that the teeth are quite poorly preserved,
which may affect character scoring. For that rea-
son, we consider BRLSI M1399 to be referable to
H. typicus. Hauffiopteryx typicus from England and
Germany formed a monophyletic group in our anal-
yses, to the exclusion of NMO 26575 and Hauffiop-
teryx altera sp. nov. (Figures 9-10).
Comparison of Hauffiopteryx typicus to NMO
26575
Maisch and Reisdorf (2006) referred a small
ichthyosaur from the late Pliensbachian of Switzer-
land to the much older Rhaetian-Sinemurian spe-
cies Leptonectes tenuirostris (Figure 12). However,
this specimen shares greater similarity with the
stratigraphically less far-removed genus Hauffiop-
teryx than with Leptonectes tenuirostris based on
its small size, cranial proportions, significant partic-
ipation of the prefrontal in the posterodorsal edge
of the external nares, and angular, closely packed
limb elements with multiple notches along the ante-
rior digit of the forelimb. NMO 26575 is distinct
from Hauffiopteryx altera in that the jugal is quite
short, and the prefrontal does not exclude the lacri-
mal from the posterior edge of the external nares.
FIGURE 12. Hauffiopteryx typicus, NMO 26575. Skull in (A) right and (B) left lateral view; 3, reconstruction, redrawn
from Maisch and Reisdorf (2006).

PALAEO-ELECTRONICA.ORG
25
NMO 26575 is more similar to H. typicus in this and
most respects, and we consider it to be referable to
H. typicus, resulting in a range extension of at least
2 million years for both the genus and the species.
One of the key differences between most skulls
referred to H. typicus and NMO 26575 is the prox-
imity between the anterior lacrimal and subnarial
process of the premaxilla in the latter, excluding the
maxilla from participation in the external narial
opening. However, the morphology observed in
GPIT/RE/12905, in which the anterior lacrimal con-
tacts the subnarial process of the premaxilla to
exclude the maxilla from the narial opening, sug-
gests that the anterior process of the lacrimal is
variable in length in H. typicus and that NMO
26575 is within the range of variation of this spe-
cies. Instraspecific variation in this part of the skull
has already been noted in other Early Jurassic ich-
thyosaurs: e.g., in Protoichthyosaurus prostaxalis
(Lomax et al., 2019a), and Stenopterygius triscis-
sus (compare Godefroit, 1994: fig. 19; Caine and
Benton, 2011: text-fig. 3).
Palaeoecology
The palaeoecology of the morphologically
similar genus Stenopterygius is relatively well
understood, and includes dietary information for
individuals over a wide range of body sizes (Dick et
al., 2016), complete ontogenetic series (von
Huene, 1922), and embryonic material (Böttcher,
1990). In contrast, Hauffiopteryx is much less
abundant. The material listed in the current contri-
bution represents the complete sample of Hauffiop-
teryx known from publicly accessible collections.
Preserved individuals fall into a much narrower
size range than Stenopterygius (Table 2 vs. Max-
well, 2012b supplementary table 1) and embryos
are unknown, limiting our understanding of ontoge-
netic variation in this genus. Recognizable prey
items are lacking as gastric contents. Thus, how
Hauffiopteryx may functionally differ from
Stenopterygius is extremely speculative.
Although referral of NMO 26575 to Hauffiop-
teryx typicus extends the stratigraphic range of the
genus and species into the upper Pliensbachian,
all finds from the Posidonienschiefer Formation are
concentrated in a very narrow stratigraphic range,
from the uppermost tenuicostatum Zone to the low-
ermost serpentinum Zone. This time period corre-
sponds to the onset to the peak of the early
Toarcian Oceanic Anoxic Event, an event that pro-
foundly influenced composition and abundance of
both vertebrate and invertebrate faunas in the
southwest German Basin (e.g., Hauff, 1921; Max-
well and Vincent, 2016). It is thus possible that
Hauffiopteryx had a particularly specialized diet or
hunting strategy, and its sudden reappearance in –
and subsequent disappearance from – the basin
was related to changes in prey abundance or habi-
tat (e.g., bottom-water anoxia forcing fish and bel-
emnites into a narrow zone near the sea surface:
Ullmann et al., 2014).
CONCLUSIONS
We found no evidence that the English and
German material referred to the genus Hauffiop-
teryx represent separate species; however, we do
find evidence that two species of Hauffiopteryx
were present in the Early Jurassic of the Southwest
German Basin: H. typicus and H. altera sp. nov.
These two taxa are differentiated primarily based
on characters pertaining to the lacrimal, prefrontal,
and jugal. In addition, we refer a specimen previ-
ously considered to be Leptonectes tenuirostris to
Hauffiopteryx typicus, extending the range of the
genus into the Pliensbachian. This result is sup-
ported by phylogenetic analysis, which recovers
Hauffiopteryx as a sister group to Stenopterygius +
Ophthalmosauridae. Hauffiopteryx represents a
valid genus, defined by a suite of synapomorphies
involving both the skull and postcranium. However,
the functional and paleoecological significance of
these characters differentiating Hauffiopteryx from
the superficially similar genus Stenopterygius are
unclear.
ACKNOWLEDGEMENTS
We would like to thank A. Schmid-Röhl
(FWD), I. Werneburg (GPIT), R. Hauff (MHH), and
D. Steinmann (NMO) for collections access, and C.
Gascó Martín for partial preparation of SMNS
80226. DC thanks C. Jaramillo (STRI), the Smith-
sonian Tropical Research Institute, the Anders
Foundation, the 1923 Fund, G.D. and J.W. John-
son, an NSERC CREATE 466283-2015, and an
NSERC Discovery Grant to H. Larsson (McGill Uni-
versity, Canada), for funding and support, and J.
Pardo-Pérez (SMNS, U. Magallanes, Chile) and C.
Gascó Martín (SMNS) for discussion and logistical
support. The suggestions of A. Wolniewicz, N.
Zverkov, and an anonymous reviewer improved the
manuscript.

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
26
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APPENDIX 1.
Selected measurements of specimens examined during this study (.xls). (Available in zipped file
at https://palaeo-electronica.org/content/2020/3078-revision-of-hauffiopteryx.)
APPENDIX 2.
Discussion of character and taxon scoring changes from past analyses.
Our phylogenetic analysis was based on the matrix
developed by Moon (2017) and modified by Max-
well et al. (2019). In addition to rescoring Hauffiop-
teryx, we made the following revisions to
characters and scoring:
Character 50: The position of the parietal foramen
is more complex than initially captured in this char-
acter. We divided state (1) into two separate states.
Rescoring affected only Ichthyosaurus.
Character 50 Parietals – location of the parietal
foramen: (0) contact between the left and right pari-
etals present anteriorly, frontal excluded from the
parietal foramen; (1) on the frontoparietal suture;
(2) entirely surrounded by the frontals (modified
from Motani 1999c, character 19).
Character 89: The transverse flange of the ptery-
goid (character 88) is absent in most ichthyosaurs
(Maisch and Matzke, 2000), which are scored as
“poorly developed” in the matrix of Moon (2017:
character 88). We therefore rescore character 89
as ‘-‘ in these cases.
Characters 165, 166: In the analysis of Moon
(2017), characters 165-166 are duplicated as cur-
rently organized (i.e. a sacrum is present by defini-
tion only if differentiated sacral ribs are present).
Moreover, no taxa in the sample have a sacrum as
defined by character 165 (ribs sutured to ilium). For
that reason, we restructure characters 165–166 as
follows:
Character 165: Sacrum (0) present (at least one
morphologically differentiated sacral rib can be
observed), (1) absent (no truly sacral ribs are pres-
ent)(Motani, 1999 character 104 [part]).
Character 166: Sacral ribs (0) two with distal
expansion, (1) one with distal expansion, (2) pres-
ent and morphologically distinct [see character
165] but no distal expansion present. This charac-
ter is treated as ordered.
Character 210: As scored by Moon (2017), this
character is uninformative. This character was
rescored based on pers. observ. of specimens at
the SMNS and from the NHMUK digital collections
interface, and such a notch separating the radial
and ulnar facets of the distal humerus was
observed in T. trigonodon, T. platyodon, and S.
integer. Because such a notch may exist even in
the presence of a humerus-intermedium contact,
character 210 was scored for all taxa.
Character 221: A small interosseous foramen is
present between the radius and ulna in T. trigono-
don, T. platyodon (see McGowan, 1979), and Sue-
voleviathan. This character was rescored
accordingly.
Character 240: In basal ichthyopterygians, meta-
carpal V is much larger than distal carpal IV,
whereas in more derived forms these elements are
subequal or metacarpal V may be lost entirely
(Maisch and Matzke 2000b, character 100). In the
character list Moon (2017), the character states
were incorrectly transcribed. We have edited this
error; the character-taxon matrix was not affected.
Mixosaurus kuhnschneyderi: Rescored for charac-
ter 118.
Guizhouichthyosaurus wolonggangense: The fol-
lowing characters were rescored based on reinter-
pretation of forelimb homologies in the original
description, in which digit I is absent (and therefore
metacarpal V is present): 217, 219, 229, 233, 236,
237, 240, 243, 247, 248. Characters 35-45 were
also rescored based on the description of the type
specimen.
Guizhouichthyosaurus tangae: character 35, 41,
229 rescored based on type description.
Callawayia neoscapularis: characters 35, 43, 229
rescored.
Ichthyosaurus communis and I. larkini: Scoring cor-
rected for Characters 42 and 43 (temporal process
of the frontal absent).
Protoichthyosaurus prostaxalis and Protoichthyo-
saurus applebyi were scored based on Lomax and
Massare, 2018; Lomax et al., 2017, 2019a,b.
Temnodontosaurus trigonodon: Rescored for char-
acter 219, since a postaxial manual accessory digit
is absent.
Temnodontosaurus crassimanus was rescored for
characters 47-48, 54, 73, 204, 207, 209, 214, 219,
226, 230, 240, 243 based on Melmore (1930).
Additionally, we assume that Melmore (1930) mis-
interpreted the anterior-posterior polarity of the

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
30
hind limb. This results in rescoring of characters
273 and 284.
Temnodontosaurus azerguensis was rescored for
characters 227, 229, and 250 based on the figures
and description of the holotype (Martin et al.,
2012); characters 259 and 263-264 were scored
based on the same.
Wahlisaurus massarae: Scoring for character 48
was corrected.
Leptonectes moorei: rescored for character 32,
233 based on pers. observ. of the holotype mate-
rial.
Eurhinosaurus longirostris: Characters 20, 36, 53,
167 rescored and character 97 scored based on
pers. observ. of specimens at the SMNS.
Excalibosaurus costini: Character 249 (number of
phalanges) rescored based on the holotype speci-
men, characters 167, 217 rescored based on
McGowan (2003).
Malawania anachronus: Characters 152, 219, 233
scored based on morphology illustrated in Fischer
et al. (2013).
Stenopterygius quadriscissus: Characters 5, 9, 20,
32, 44, 61, 87, 152, 233 rescored based on pers.
observ; character 82 rescored based on pers.
observ.
Stenopterygius triscissus: Characters 5, 20, 152
rescored based on pers. observ; character 82
scored based on pers. observ.
Stenopterygius uniter: Characters 5, 9, 20, 152,
241 rescored based on pers. observ; character 82
rescored based on pers. observ.
Stenopterygius aaleniensis: Scoring of character
241 changed to ‘?’ as the metacarpal row is not
preserved in this taxon; character 5 (subnarial pro-
cess) also rescored based on pers. observ.
Chacaicosaurus cayi: Characters 233, 247–248
rescored based on Fernández (1994).
Ophthalmosaurus icenicus: Character 41 rescored
as present, based on the separation of the post-
frontal from the parietal in dorsal view by a process
of the frontal.
Caypullisaurus bonapartei: Scoring for character
247–248 changed, as manual metacarpal V is
present in these taxa (Fernández, 2001).
Arthropterygius chrisorum: Character 177 changed
to ‘?’ as the caudal region is not well-enough pre-
served to evaluate this character.
Paraophthalmosaurus kabanovi: Scoring for char-
acter 247 changed to ? because the limb is incom-
pletely preserved in this specimen.
Muiscasaurus catheti: rescored as ‘?’ for charac-
ters 11-12, since the maxilla-lacrimal suture is
unclear.
Sveltonectes insolitus was rescored for character
227.
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MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
32
APPENDIX 3.
Character list, copied directly from Moon (2017). Text in red corresponds to changes to the origi-
nal character list that were introduced in Maxwell et al. (2019); text in blue indicates characters
that were modified for the current study (characters 50, 165–166 only). See Appendix 2 for dis-
cussion and references. Characters 100, 107, 153, 166, and 219 are treated as ordered.
Skull
Character 1 Snout – extremely slender premaxil-
lary segment, < ¼ the maximum lateral width of the
posterior of the skull: (0) absent (1) present (Motani
1999c, character 34). This is modified from
Motani’s (1999c) character 34 by defining a spe-
cific boundary of ‘slender’. Motani’s original charac-
ter separates several taxa, especially his
‘Eurhinosauria’. To maintain this distinction this
character is defined as the width of the snout
where the premaxillae exclude the nasals from dor-
sal view – the nasals anteriormost dorsal exposure
– compared to the maximum width of the post-nar-
ial skull.
Character 2 Premaxilla – supranarial process: (0)
present (1) absent (modified from Maisch and
Matzke 2000b, character 9; and Maxwell 2012,
character 1).
Character 3 Premaxilla – size of supranarial pro-
cess: (0) large, extending > ⅓ of the external
narial length (1) small, extending < ⅓ of the exter-
nal narial length (modified from Maisch and Matzke
2000b, character 9; and Maxwell 2012, character
1).
Character 4 Premaxilla – subnarial process: (0)
absent (1) present (modified from Maisch and
Matzke 2000b, character 10; and Maxwell 2012,
character 1).
Character 5 Premaxilla – size of the subnarial pro-
cess: (0) small, extending < ⅓ of the external
narial length (1) large, extending > ⅓ of the exter-
nal narial length (modified from Maisch and Matzke
2000b, character 10; and Maxwell 2012, character
1).
Character 6 Premaxilla-palatine – contact in ven-
tral view: (0) absent (1) present, relatively broad
(Druckenmiller and Maxwell 2010, character 15).
Character 7 Maxilla – reduction: (0) absent, ≥ ½ of
the length of the snout (1) present, < ½ the length
of the snout (modified from Sander et al. 2011,
character 106). The reduction of the maxilla is
defined more specifically than Sander et al.’s
(2011) character 106. While this is defined relative
to the length of the snout as a whole, the dorsoven-
tral exposure and contribution should also be con-
sidered (see character 9).
Character 8 Maxilla – bearing teeth: (0) present (1)
absent. See character 7.
Character 9 Maxilla – location of the laterally
exposed greatest dorsoventral extent: (0) posterior
to the external naris (1) ventral or anterior to the
external naris (modified from Druckenmiller and
Maxwell 2010, character 4). State one has been
modified to include ‘ventral to the external naris’.
Character 10 Maxilla – length of the premaxillary
process: (0) short, extends approximately one or
less narial lengths anterior to the external naris (1)
long, extends approximately 1.5 or more narial
lengths anterior to the external naris (Maxwell
2012, character 2).
Character 11 Maxilla – postnarial process exposed
laterally: (0) present (1) absent (modified from
Maisch and Matzke 2000b, character 11). The
postnarial process of the maxilla is a dorsal exten-
sion of the maxilla posterior to the external naris,
this is the processus postnarialis of Maisch and
Matzke (1997a); it is equivalent to the dorsal lam-
ina of Motani (1999c).
Character 12 Maxilla – size of the postnarial pro-
cess exposure: (0) large (1) tiny (modified from
Maisch and Matzke 2000b, character 11). Clarified
that this refers to exposure of the postnarial pro-
cess.
Character 13 Maxilla – size of the jugal process:
(0) long, extending as far under the orbit as the
lachrymal in lateral view (1) short, hidden in lateral
view by the jugal (Maxwell 2012, character 3).
Character 14 Maxilla – contacts prefrontal: (0)
absent (1) present (Maisch and Matzke 2000b,
character 12).
Character 15 Maxilla – contacts external naris in
external lateral view: (0) present (1) absent (modi-
fied from Fernández 2007a, character 2; after
Fischer et al. 2011, character 9; and Fischer 2013,
character 9).
Character 16 Nasal – anteroposterior extent of
dorsal exposure in the prenarial rostrum: (0) sub-
stantial, over 40% (1) reduced, less than 40%
(Maxwell 2012, character 4).
Character 17 Nasal posterior extent: (0) reaches
back to the orbit (1) reaches distinctly over the orbit
(Maisch and Matzke 2000b, character 14).
Character 18 Narial shelf: (0) absent (1) present
(Jiang et al. 2006, character 4). This narial shelf is
anterior to the external naris, bordered medially by
the nasosupraorbital ridge (Jiang et al. 2006).

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33
Character 19 Nasal – borders external naris: (0)
present (1) excluded (Sander 2000, character 7).
Character 20 Nasal – descending process on the
interior posterior border of the nares: (0) absent (1)
present (Fernández 2007a, character 2).
Character 21 Nasal-postfrontal – contact: (0)
absent (1) present (modified from Nicholls and
Manabe 2001, character 3).
Character 22 Nasal-postfrontal contact – size: (0)
small (1) extensive, separating frontals and pre-
frontals in dorsal view (modified from Nicholls and
Manabe 2001, character 3).
Character 23 Excavatio internasalis: (0) absent (1)
present (Maisch and Matzke 2000b, character 16).
Character 24 Lachrymal – anterior extent: (0)
reaches external naris (1) is excluded from the
external naris by the dorsal process of the maxilla
and/or the ventral process of the nasal (Sander
2000, character 10). The polarity of this character
was reversed by Maxwell (2012, character 5).
Character 25 Lachrymal – numerous small-to-
medium-sized nutritive foramina: (0) absent (1)
present (Sander et al. 2011, character 111). This
character refers to millimetre-size nutritive foram-
ina that perforate the lachrymal and are only
recorded in Shastasaurus.
Character 26 External nares – shape: (0) small,
round to ovate (1) elongate (2) elongate and com-
plexly lobate (Sander 2000, character 8). As this
character defines shape, states one and two are
considered suitably different that this should not be
coded with reductive methods.
Character 27 External nares – orientation: (0) dor-
solateral (1) lateral, scarcely visible in dorsal view
(Motani 1999c, character 4).
Character 28 Jugal – shape: (0) triradiate (1)
lunate or J-shaped (Motani 1999c, character 24).
Compare this with character 31.
Character 29 Jugal – anterior margin shape: (0)
tapering, running between the lachrymal and max-
illa (1) broad and fanlike, covering a large area of
the maxilla ventrolaterally (Druckenmiller and Max-
well 2010, character 6).
Character 30 Jugal – extent of anterior margin: (0)
terminates posterior to the anterior end of the lach-
rymal (1) reaches or surpasses the anterior end of
the lachrymal (Roberts et al. 2014, character 11).
Character 31 Jugal – dorsal ramus shape: (0) well-
developed and strongly curved dorsally (1) poorly
developed, jugal essentially straight (Maxwell
2012, character 8). This character is exclusive of
character 28: poor development of the dorsal
ramus does not preclude a J-shaped or triradiate
jugal, although this may be less apparent.
Character 32 Jugal – contact between the postor-
bital process and the squamosal: (0) absent (1)
present (Sander 2000, character 31).
Character 33 Jugal-quadratojugal – external con-
tact: (0) absent (1) present (Motani 1999c, charac-
ter 23). This was included as a new character by
Roberts et al. (2014), who explicitly included the
postorbital to separate the jugal and quadratojugal.
Character 34 Jugal-quadratojugal notch – deep,
forming a pronounced ventral emargination of the
cheek: (0) present (1) absent (Jiang et al. 2005,
character 24). This character is exclusive of char-
acter 79 as the ventral margin of the quadratojugal
may be concave without forming a distinct emargi-
nation of the cheek.
Character 35 Prefrontal – dorsal exposure: (0)
broadly exposed (1) present, but limited by the
anterior process of the postfrontal and posterior
process of the nasal (2) little to none (modified
from Maxwell 2012, character 12).
Character 36 Prefrontal-external naris – contact:
(0) absent (1) present (Druckenmiller and Maxwell
2010, character 7).
Character 37 Prefrontal-postfrontal – contact: (0)
absent, the dorsal margin of the orbit is formed by
the frontal (1) present, eliminating the frontal from
the dorsal margin of the orbit (Motani 1999c, char-
acter 8). This character incorporates the revised
interpretation of the skull of Ichthyosaurus and
Stenopterygius (Motani 2005), but character states
may have been revised. This also applies to subse-
quent skull roof characters.
Character 38 Prefrontal and postfrontal – high
supraorbital crest: (0) absent (1) present (Maisch
and Matzke 2000b, character 22).
Character 39 Frontals – dorsal view: (0) strongly
convex at the anterior edge of the parietal foramen
(1) flat to concave, overlapped by surrounding ele-
ments (Maxwell 2012, character 13). Overlapping
by surrounding elements may be separated into
another character, however, this has not clearly
been seen to warrant this distinction.
Character 40 Frontal – location of the widest expo-
sure: (0) located posteriorly (1) at nasal suture
(Motani 1999c, character 15).
Character 41 Frontal – temporal process: (0)
absent (1) present (Fischer et al. 2011, character
14).
Character 42 Frontal – participates in the supra-
temporal fenestra in dorsal view: (0) absent (1)
present (modified from Druckenmiller and Maxwell
2010, character 9; and Fischer et al. 2011, charac-
ter 14). This and the next character are separated
for reductive coding.

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
34
Character 43 Frontal – size of participation in the
supratemporal fenestra: (0) small (1) extensive
(modified from Druckenmiller and Maxwell 2010,
character 9).
Character 44 Frontal and parietal – relative dorsal
exposure size: (0) frontal as large or larger than the
parietal (1) frontal smaller than the parietal (Maisch
and Matzke 2000b, character
17).
Character 45 Parietal – dorsal view contribution to
the anterior margin of the supratemporal fenestra:
(0) no contribution (1) minor contribution (2) large,
almost completely excluding the postfrontal from
contact (modified from Maxwell 2012, character
14).
Character 46 Parietal ridge: (0) absent (1) present
(Motani 1999c, character 17).
Character 47 Parietal shelf – orientation (0)
obliquely oriented; (1) horizontally oriented (modi-
fied from Nicholls and Manabe 2001, character 8).
Character 48 Parietal shelf – size: (0) large (1)
reduced (modified from Nicholls and Manabe 2001,
character 8).
Character 49 Parietals – separation of anterior
processes of the right and left: (0) narrow, forming
parietal fork, and frontal dorsally visible along the
pineal foramen (1) widely open, resulting in
absence of clear fork (Motani 1999c, character 19).
This character may be coded as inapplicable if the
anterior processes of the parietals contact (charac-
ter 50).
Character 50 Parietals – location of the parietal
foramen: (0) contact between the left and right pari-
etals present anteriorly, frontal excluded from the
parietal foramen; (1) on the frontoparietal suture;
(2) entirely surrounded by the frontals (modified
from Motani 1999c, character 19).
Character 51 Parietals – anterior fork elevated: (0)
absent (1) present (Nicholls and Manabe 2001,
character 10). This character is coded as inapplica-
ble if no anterior parietal fork is present (character
49).
Character 52 Postparietals – additional bone sep-
arating the parietal and supratemporal: (0) absent
(1) present (modified from Thorne et al. 2011, char-
acter 18).
Character 53 Parietal – size of the supratemporal
process: (0) short (1) long (modified from Thorne et
al. 2011, character 18).
Character 54 Parietal foramen – anteroposterior
position: (0) approximately equal to the anterior
edge of the supratemporal fenestra (1) well ante-
rior to the anterior edge of the supratemporal
fenestra (Maxwell 2012, character 15).
Character 55 Postfrontal – size of the posterior
flange: (0) delicate and narrow, not extending ven-
trally to the posterior orbital rim (1) robust and tri-
angular, approaching posterior orbital rim
(Druckenmiller and Maxwell 2010, character 12).
The posterior flange on the postfrontal is found in
all ichthyosaurs (Motani 1999c; Thorne et al. 2011),
but the size of this varies (Druckenmiller and Max-
well 2010).
Character 56 Postfrontal-postorbital – size of con-
tact: (0) narrow (1) broad (Roberts et al. 2014,
character 16).
Character 57 Postfrontal-supratemporal – contact:
(0) absent (1) present (Sander 2000, character 28).
This is exclusive of character 55 as contact
between the postfrontal and supratemporal may be
made whether the posterior flange is large or small.
Character 58 Postorbital – shape: (0) triradiate (1)
lunate, without posterior process (Motani 1999c,
character 11).
Character 59 Postorbital – size: (0) broad (1) nar-
row (Fernández 2007a, character 7).
Character 60 Postorbital – participates in the
supratemporal fenestra: (0) present (1) absent
(Motani 1999c, character 12).
Character 61 Postorbital-supratemporal – contact
in external view: (0) present (1) absent (Maxwell
2012, character 6).
Character 62 Supratemporal – enlargement: (0)
small, minimal posterior exposure (1) moderate,
forming posterior border of the supratemporal
fenestra (2) strongly enlarged, forms significant
portion of the posterior and lateral borders to
supratemporal fenestra and skull roof (modified
from Sander 2000, character 26). The definitions
for ‘small’ and ‘enlarged’ are clarified.
Character 63 Supratemporal – anterodorsal sheet
overhanging the supratemporal fenestra: (0)
absent (1) present (Maisch and Matzke 2000b,
character 25).
Character 64 Supratemporal – size of the
descending ramus: (0) pronounced, reaching at
least half of the total height of the quadrate (1)
reduced, a small process medial to the quadrate
articulation (Maxwell 2012, character 17).
Character 65 Supratemporal-stapes – contact: (0)
absent (1) present (Fischer et al. 2013, character
52).
Character 66 Sagittal eminence: (0) present (1)
absent (Fischer et al. 2011, character 13).
Character 67 Supratemporal – orientation of pari-
etal ramus in dorsal view (0) oblique, (1) horizontal.
This character may not be independent from the

PALAEO-ELECTRONICA.ORG
35
orientation of the parietal shelf, but can be scored
in the absence of a clear parietal shelf.
Character 68 Supratemporal – relative anterior
extent of the lateral and parietal rami in dorsal view
(0) subequal, (1) lateral ramus extending much fur-
ther anteriorly.
Character 69 Squamosal: (0) present (1) absent.
This character is added, and characters 70 to 72
are modified, and which may be coded as inappli-
cable, for reductive coding.
Character 70 Squamosal – shape: (0) triangular
(1) squared (Fischer et al. 2011, character 16).
Character 71 Squamosal – posterior descending
process: (0) absent (1) present (modified from
Fernández 2007a, character 4). The absence of
the squamosal is coded separately (character 69).
Character 72 Squamosal – participates in supra-
temporal fenestra: (0) present (1) excluded by
supratemporal and/or postfrontal (Nicholls and
Manabe 2001, character 6).
Character 73 Supratemporal fenestrae – width in
dorsal aspect: (0) posterior half narrower than
anterior half (1) anterior and posterior halves
approximately equal in width (Druckenmiller and
Maxwell 2010, character 11).
Character 74 Anterior terrace of the supratemporal
fenestra: (0) absent (1) present (modified from
Motani 1999c, character 14).
Character 75 Anterior terrace of the supratemporal
fenestra – extent: (0) small, reaching the posterior
part of the frontal anteriorly (1) large, reaching the
nasal anteriorly (modified from Motani 1999c, char-
acter 14). See character 74.
Character 76 Skull roof – posterior margin
indented in dorsal view: (0) deep (1) moderate
(Maisch and Matzke 2000b, character 27).
Character 77 Quadratojugal – location of the main
body: (0) laterally (1) posteriorly (Maisch and
Matzke 2000b, character 28).
Character 78 Quadratojugal – exposure: (0) broad
in lateral view (1) narrow and most extensively
exposed in posterior view (Maxwell 2012, charac-
ter 8).
Character 79 Quadratojugal – shape of the ventral
edge: (0) concave (1) ventral edge straight or
entirely covered by the jugal (Maxwell 2012, char-
acter 9). See also character 34.
Character 80 Quadratojugal – distinctly offset
quadrate process: (0) present (1) absent (Maisch
and Matzke 2000b, character 29).
Character 81 Quadrate – dorsal articulation loca-
tion: (0) enclosed laterally by the squamosal (1)
articulates dorsomedially with the supratemporal
only (Maxwell 2012, character 11). This character
may be coded as inapplicable if the squamosal is
absent (character 69), although this implies state
(1).
Character 82 Quadrate – location of the stapedial
facet on the posterior surface: (0) ventral half (1)
dorsal half (Druckenmiller and Maxwell 2010, char-
acter 21).
Character 83 Orbit – shape of the anterior margin:
(0) irregular (1) regularly rounded (2) angled (modi-
fied from Maisch and Matzke 2000b, character 23).
The additional state ‘angled’ is added for the condi-
tion in e.g. Cryopterygius kristiansenae.
Character 84 Postorbital skull – length compared
to orbital diameter: (0) > ⅓ (1) < ⅓ (Jiang et al.
2005, character 7).
Character 85 Cheek – orientation: (0) mostly lat-
eral (1) largely posterior (Motani 1999c, character
25).
Character 86 Interpterygoidal vacuity: (0) present
(1) absent (modified from Motani 1999c, character
27). Other characters referring to a ‘closed palate’
(Jiang et al. 2005, character 12) and exposure of
the basis cranii (Maisch and Matzke 2000b, char-
acter 44) are included within this. This character is
modified into a simple presence/absence dichot-
omy.
Character 87 Palatine – contributes to subtempo-
ral fenestra: (0) posteriorly forms anterior edge (1)
posteriorly excluded from the subtemporal fenestra
(Maxwell 2012, character 25).
Character 88 Pterygoid – transverse flange: (0)
well-developed (1) poorly developed (modified
from Motani 1999c, character 26). The develop-
ment and orientation of the transverse flange of the
pterygoid are separated for reductive coding (char-
acters 88 and 89).
Character 89 Pterygoid – orientation of the trans-
verse flange: (0) anterolateral (1) posterolateral
(modified from Motani 1999c, character 26). See
character 88.
Character 90 Pterygoid – posteromedial process:
(0) present (1) absent (Maisch and Matzke 2000b,
character 35).
Character 91 Vomer – number of dorsal pro-
cesses: (0) one (1) two (Druckenmiller and Max-
well 2010, character 17). The vomer, particularly
dorsally, is poorly known; while this character is
included, its coding completeness is low.
Character 92 Epipterygoid – ossified: (0) present
(1) absent.
Character 93 Basis cranii – largely formed by: (0)
parasphenoid (1) basisphenoid (Maisch and
Matzke 2000b, character 41).

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
36
Character 94 Basioccipital – shape of the condyle:
(0) flat or slightly concave (1) hemispherical
(Motani 1999c, character 31).
Character 95 Basioccipital – notochordal pit on the
condylar surface: (0) absent (1) present. See char-
acter 96.
Character 96 Basioccipital – location of noto-
chordal pit on the condylar surface: (0) central (1)
dorsal.
Character 97 Basioccipital peg: (0) present (1)
absent (Fischer et al. 2011, character 20).
Character 98 Basioccipital – prominent ventral
tubers separated by a deep notch: (0) present (1)
absent (modified from Maxwell 2012, character
24). This character has been simplified to pres-
ence/absence.
Character 99 Basioccipital – extracondylar area:
(0) present (1) absent. This character is added as,
in some taxa, the extracondylar area may be
entirely lost. This is incorporated into Fischer et al.
(2013, character 20).
Character 100 Basioccipital – size of the ventral
extracondylar area: (0) larger than the dorsoventral
height of the condyle (1) smaller than the condyle
but still extensive (2) reduced to a thin strip (Max-
well 2012, character 23). This is similar to Fischer
et al. (2013, character 20). This character is treated
as ordered.
Character 101 Basioccipital – contribution to the
floor of the foramen magnum: (0) absent, excluded
by the exoccipitals (1) present, the portion contrib-
uting being flat, or concave, and covered in fin-
ished bone (Maxwell 2012, character 21).
Character 102 Parabasisphenoid – base of
basipterygoid processes in dorsal or ventral view:
(0) offset and anteroposteriorly narrow, much less
than half the anteroposterior length of the paraba-
sisphenoid (1) markedly expanded, forming
approximately 50% or more of the anteroposterior
length of the parabasisphenoid.
Character 103 Carotid foramen – pairing: (0)
paired (1) unpaired (modified from Maisch and
Matzke 2000b, character 42; after Maxwell 2010,
character 10). These two characters are joined, as
they are slightly different versions of each other.
Character 104 Carotid foramen – location: (0)
basioccipital and (1) parabasisphenoid (modified
from Maisch and Matzke 2000b, character 42; after
Maxwell 2010, character 10).
Character 105 Parasphenoid – shape of the base
of the cultriform process: (0) wide, gently grading
into the basal plate (1) distinctly narrowed, well off-
set from the basal plate (Maisch and Matzke
2000b, character 43).
Character 106 Parabasisphenoid – shape in dor-
sal or ventral view: (0) anterior edge (including
basipterygoid processes) less than 2/3 as long as
posterior edge (1) anterior and posterior edges
similar in length; (2) posterior edge less than 2/3 as
long as anterior edge.
Character 107 Parabasisphenoid – location of the
carotid foramen: (0) opening near the middle of the
ventral surface, (1) opening on the posterior third of
the ventral surface, (2) opening on the posterior
surface [treated as ordered] (modified from Maisch
and Matzke 2000b, character 42; after Maxwell
2010, character 10). See characters 103 and 104.
In cases where the carotid foramen is on the
basioccipital rather than the parabasisphenoid
(character 104), character 107 is coded as inappli-
cable.
Character 108 Opisthotic – shape of the paraoc-
cipital process: (0) short and robust (1) elongate
and slender (Fischer et al. 2012, character 20).
Character 109 Supraoccipital – orientation of the
exoccipital processes: (0) parallel (1) divergent
(Maxwell 2012, character 19).
Character 110 Exoccipital – contribution to fora-
men magnum: (0) exoccipitals make up the largest
lateral contribution (1) supraoccipital contribution
almost equal to that of exoccipitals (Maxwell 2012,
character 20).
Character 111 Stapes – size of the proximal head:
(0) slender, much smaller than opisthotic proximal
head (1) massive, as large or larger than opisthotic
(Fischer et al. 2011, character 21).
Character 112 Stapes – relative size of heads: (0)
lateral head less robust than the medial head (1)
both medial and lateral heads robust (Maxwell
2012, character 18).
Character 113 Stapes – size of shaft in adults: (0)
thick (1) slender and gracile (Roberts et al. 2014,
characters 25).
Character 114 Lower jaw: (0) well developed (1)
reduced relative to lower jaw (Maxwell 2012, char-
acter 26).
Character 115 Lower jaw – development: (0) nor-
mal (1) slender, reduced in diameter (Sander et al.
2011, character 108).
Character 116 Lower jaw – ventral margin in lat-
eral view: (0) straight, or nearly so (1) markedly
concave approximately ventral to the external
nares (modified from Sander 2000, character 37).
Character 117 Dentary – labial shelf: (0) absent (1)
present (Jiang et al. 2006, character 14).
Character 118 Surangular – makes up most of the
posterior lateral surface of the lower jaw: (0) absent

PALAEO-ELECTRONICA.ORG
37
(1) present (Maisch and Matzke 2000b, character
38).
Character 119 Surangular – dorsal (paracoronoid)
process just anterior to the jaw articulation: (0)
absent (1) present (Sander 2000, character 42).
Character 120 Angular – extent of anterior lateral
exposure: (0) much smaller than the surangular’s
exposure (1) extensive, at least as high and anteri-
orly as the surangular’s exposure (modified from
Motani 1999c, character 32; after Fischer et al.
2011, character 22; and Maxwell 2012, character
28).
Character 121 Angular – extent of posterior lateral
exposure: (0) minimal, covers less than half of the
lateral surface of the retroarticular process (1)
extensive, surangular exposure reduced to a thin
strip on the lateral surface of the retroarticular pro-
cess (Maxwell 2012, character 29).
Character 122 Splenial – participation in the man-
dibular symphysis: (0) more extensive than the
dentary (1) present but restricted to the posterior
half (Maxwell 2012, character 27).
Character 123 Coronoid – ossified: (0) present (1)
absent (modified from Maisch and Matzke 2000b,
character 45). This character is separated for
reductive coding (see character 124).
Character 124 Coronoid – shape: (0) laterally flat-
tened (1) narrow and elongate (modified from
Maisch and Matzke 2000b, character 45). May be
coded as inapplicable if the coronoid is not present/
ossified (character 123).
Character 125 Coronoid process: (0) flat (1) ele-
vated (2) drawn into a pointed process (modified
from Sander 2000, character 41). This refers to the
true process on the coronoid, so may be coded as
inapplicable if this is not present/ossified (character
123).
Character 126 Lower jaw glenoid – deeply exca-
vated: (0) absent (1) present (Sander 2000, char-
acter 43).
Character 127 Articular – transverse width: (0)
wide with dorsally deeply concave retroarticular
process (1) narrow (Maisch and Matzke 2000b,
character 47).
Character 128 Teeth: (0) present (1) absent (modi-
fied from Maisch and Matzke 2000b, character 4;
after Fischer et al. 2011, character 4; and Sander
et al. 2011, character 109). The presence/-absence
of teeth is separated for reductive coding alongside
character 129; subsequent dentition characters
may become inapplicable in this case.
Character 129 Dentition – complete, well-devel-
oped dentition retained in adults: (0) present (1)
strongly reduced (modified from Maisch and
Matzke 2000b, character 4; after Fischer et al.
2011, character 4; and Sander et al. 2011, charac-
ter 109). This character is separated from edentu-
lism as it refers to the size and number of teeth
(character 128).
Character 130 Dentition – tooth implantation after
Motani (1997a): (0) subthecodont (1) thecodont (2)
aulacodont (modified from Sander 2000, character
52). Here, ankylosed and ichthyosaurian theco-
donty are separated into separate characters
(character 131).
Character 131 Dentition – bony fixation: (0) pres-
ent (1) absent (Motani 1999c, character 43).
Character 132 Plicidentine: (0) absent (1) present
(Motani 1999c, character 36).
Character 133 Dentition – number of tooth rows:
(0) one (1) two (2) irregular pavement (Sander
2000, character 50).
Character 134 Upper dental groove: (0) absent (1)
present (modified from Motani 1999c, character
41). Motani’s (1999c) characters 41 and 42 have
each been separated to form characters 134 to 137
by reductive coding. These are not excluded by
edentulism (character 128): the dental groove may
be retained.
Character 135 Upper dental groove – location: (0)
throughout jaw margin (1) only anteriorly (modified
from Motani 1999c, character 41). This character
may be inapplicable if the upper dental groove is
absent (character 134).
Character 136 Lower dental groove: (0) absent (1)
present (modified from Motani 1999c, character
42). See character 134.
Character 137 Lower dental groove – location: (0)
throughout jaw margin (1) only anteriorly (modified
from Motani 1999c, character 42). This character
may be inapplicable if the lower dental groove is
absent (character 136).
Character 138 Dentition – number of maxillary
positions ventral to the jugal: (0) less than three (1)
four or more (Druckenmiller and Maxwell 2010,
character 16).
Character 139 Palatine teeth: (0) present (1)
absent.
Character 140 Pterygoidal teeth: (0) present (1)
absent (Motani 1999c, character 44).
Character 141 Dentition – replacement: (0) irregu-
lar (1) regular (Sander 2000, character 51).
Character 142 Dentition – position of replacement
teeth to the pulp cavity of the predecessor: (0) out-
side (1) inside (Motani 1999c, character 35).
Character 143 Dentition – ornamentation of the
enamel: (0) prominent ridges and grooves (1) thin

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
38
and smooth (2) thick and bumpy (Maxwell 2012,
character 30).
Character 144 Dentition – shape of the root cross-
section in adults: (0) rounded (1) quadrangular
(modified from Fischer et al. 2011, character 3;
after Fischer et al. 2012, character 3).
Character 145 Dentition – dentine infolding (0) stri-
ations not externally visible basal to the crown in
the apical third of the root; (1) forming prominent
grooves and ridges basal to the crown in the apical
third of the root.
Character 146 Dentition – dentine infolding (0)
creating clear externally visible striations in the
basal half of the root in functional teeth, (1) com-
pletely obscured by cellular cementum.
Character 147 Dentition – definition of the base of
the enamel layer: (0) poorly defined or invisible (1)
well defined and precise (Fischer et al. 2011, char-
acter 2).
Character 148 Dentition – horizontal section of the
tooth crown: (0) circular (1) mesiodistally com-
pressed (2) laterally compressed (modified from
Motani 1999c, character 37). This has been
restricted to the tooth crown only.
Character 149 Dentition – shape of the posterior
tooth crown: (0) conical (1) rounded (2) flat (Motani
1999c, character 39).
Postcranial axial skeleton
Character 150 Atlas pleurocentrum – shape: (0)
anteriorly convex (1) deeply concave (Maisch and
Matzke 2000b, character 49).
Character 151 Atlas-axis: (0) separate (1) co-ossi-
fied in adults (Maisch and Matzke 2000b, character
50).
Character 152 Atlas-axis – neural spines: (0) com-
pletely overlapping, may be fused (1) functionally
separate, never fused (Druckenmiller and Maxwell
2010, character 26).
Character 153 Presacral vertebrae – number: (0)
n < 40 (1) 40 ≤ n < 55 (2) 55 ≤ n (modified from
Motani 1999c, character 95). [treated as ordered]
Character 154 Central facets: (0) bulging (1) cen-
tral face straight-sided (modified from Sander
2000, character 58).
Character 155 ‘Cervical’ vertebrae – diapophysis-
neural arch contact extent: (0) up to middle dorsal
region (1) anterior dorsal region (Fischer et al.
2011, character 23).
Character 156 ‘Cervical’ vertebrae – centrum to
neural arch height: (0) < 2 (1) ≤ 2 (modified from
Sander 2000, character 61). This has been simpli-
fied to a dichotomy.
Character 157 ‘Cervical’ centra – bicipital rib facet:
(0) absent (1) present (Motani 1999c, character
99).
Character 158 Postcervical to presacral centra –
number of rib articulations: (0) holocephalous
throughout (1) dicephalous in posterior dorsal and
anterior caudal region, remainder holocephalous
(2) dicephalous throughout (Nicholls and Manabe
2001, character 38).
Character 159 Dorsal centra – increase in height
from anterior to posterior: (0) absent (1) present
(Sander 2000, character 55).
Character 160 Anterior dorsal neural spine –
shape: (0) normal (1) narrow, high and straight
(Motani 1999c, character 102).
Character 161 Anterior dorsal/thoracic zygapophy-
ses – pairing: (0) paired (1) bilobate (2) unpaired
(modified from Maisch and Matzke 2000b, charac-
ter 51). The additional state ‘bilobate’ is added to
separate when the two zygapophyses meet medi-
ally.
Character 162 Anterodorsal centra – rib facet
position: (0) confluent with anterior face in at least
some centra (1) not confluent in any (Motani
1999c, character 101).
Character 163 Anterodorsal centra – synapophy-
sis shape: (0) symmetrical, hourglass-shaped (1)
asymmetrical with irregular swellings and constric-
tions (modified from Nicholls and Manabe 2001,
character 40).
Character 164 Posterior dorsal centra – outline:
(0) ≤ 3.5× high as long (1) ≤ 4× high as long
(Fischer et al. 2011, character 24). These codings
are the reverse of Maxwell (2010, character 15),
but direction is defined by the outgroup to the clade
where the state changes.
Character 165 Sacrum: (0) present, at least one
morphologically differentiated sacral rib can be
observed (1) absent, no truly sacral ribs are pres-
ent (Motani, 1999 character 104 [part]).
Character 166 Sacral ribs: (0) two with distal
expansion, (1) one with distal expansion, (2) pres-
ent and morphologically distinct [see character
165] but no distal expansion present. Is inapplica-
ble when sacrum is absent/undifferentiated (char-
acter 165). [treated as ordered]
Character 167 Tail – length relative to precaudal
body: (0) longer (1) shorter (Maisch and Matzke
2000b, character 65; Fischer et al. 2013, character
33).
Character 168 Tail – lunate tail fin: (0) none (1)
well-developed (Maisch and Matzke 2000b, char-
acter 66).

PALAEO-ELECTRONICA.ORG
39
Character 169 Caudal peak: (0) absent (1) present
(Motani 1999c, character 96). This character is
separate from character 168: the caudal peak is
interpreted as an early modification of the tail to an
aquatic lifestyle, with development of a tail fin
(Motani 1999c; McGowan & Motani 2003).
Character 170 Caudal centra – mid-region height
change: (0) gradual decrease (1) increase (2) sud-
den decrease (Motani 1999c, character 98).
Character 171 Caudal centra – elongation: (0)
elongate (1) short (Maisch and Matzke 2000b,
character 59).
Character 172 Anterior caudal vertebrae – neural
arch to centrum height: (0) < 2 (1) ≤ 2 (modified
from Sander 2000, character 63).
Character 173 Anterior to middle caudal centra –
spinous process shape: (0) very long and slender
(1) short and wide (Maisch and Matzke 2000b,
character 61).
Character 174 Middle caudal centra – neural spine
inclination: (0) distinctly anterior (1) vertical or pos-
terior (Maisch and Matzke 2000b, character 60).
Character 175 Tail fin centra – shape: (0) strongly
laterally compressed (1) as wide as high (Maxwell
2010, character 16).
Character 176 Chevrons – ossified: (0) present (1)
absent.
Character 177 Chevrons: (0) present throughout
caudal region (1) absent in apical region.
Character 178 Rib – cross-sectional shape at mid-
shaft: (0) oval or with posterior groove (1) figure-of-
eight (2) round with anterior and posterior flanges
(3) (modified from Sander 2000, character 73).
State three is added to code for the outgroup
Hupehsuchus nanchangensis.
Character 179 Gastralia – V-shaped median ele-
ment: (0) present (1) absent (modified from Sander
2000, character 75).
Character 180 Gastralia – lateral elements: (0)
one lateral element per side (1) two lateral ele-
ments per side (modified from Sander 2000, char-
acter 75).
Appendicular skeleton
Character 181 Interclavicle – shape: (0) cruciform
(1) triangular (1) T-shaped (Motani 1999c, charac-
ter 45).
Character 182 Clavicle – expanded medial flange:
(0) present (1) absent, clavicle slender and narrow
medially (Maisch and Matzke 2000b, character 68).
Character 183 Coracoid – shape: (0) mediolater-
ally wider than anteroposteriorly long (1) approxi-
mately equidimensional (2) anteroposteriorly
longer than mediolaterally wide (Maxwell 2012,
character 32).
Character 184 Coracoid – medial margin: (0) well-
rounded (1) straight symphysis (Maisch and
Matzke 2000b, character 73).
Character 185 Coracoid – anterior notch: (0) pres-
ent (1) absent (modified from Maxwell 2012, char-
acter 33).
Character 186 Coracoid – posterior notch: (0)
present (1) absent (modified from Maxwell 2012,
character 34).
Character 187 Coracoid – lengths of anterior and
posterior extensions: (0) anterior extension longer
than posterior (1) reduced anterior extension
(Maisch and Matzke 2000b, character 74).
Character 188 Coracoid – anteromedial process:
(0) present (1) absent (Fischer et al. 2011, charac-
ter 29).
Character 189 Coracoid – glenoid and scapular
facet sizes: (0) very small (1) enlarged (Maisch and
Matzke 2000b, character 72).
Character 190 Coracoid – medial facet for the
scapula: (0) absent (1) present (Arkhangelsky &
Zverkov 2014, character 52).
Character 191 Scapula – anterior expansion proxi-
mally: (0) present (1) absent (modified from Max-
well 2012, character 31). Maxwell et al.’s (2012)
character is modified to presence/- absence of
acromion process, with anterior expansion (states
1 and 2) separated into character 192.
Character 192 Scapula – prominent acromion pro-
cess: (0) present (1) absent (modified from Max-
well 2012, character 31).
Character 193 Scapula – shape of the anterodor-
sal margin: (0) fan-shaped (1) emarginated (2)
straight (Motani 1999c, character 46).
Character 194 Scapula – size of the glenoid contri-
bution: (0) at least as large as the coracoid facet
(1) markedly smaller than the coracoid facet
(Fischer et al. 2012, character 27).
Character 195 Scapula – posterior process: (0)
distinct and large (1) reduced (Maisch and Matzke
2000b, character 71).
Character 196 Scapula – blade shaft: (0) absent
(1) present at least proximally (Motani 1999c, char-
acter 47).
Character 197 Scapula – angle subtended by the
axis and glenoid facet: (0) nearly parallel (1) 60° or
more (Motani 1999c, character 48).
Character 198 Humerus – differentiated and offset
proximal head: (0) present (1) absent (Maisch and
Matzke 2000b, character 75).
Character 199 Humerus – anterior margin: (0)
straight, convex (1) with small central notch (2)

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
40
markedly concave (modified from Maisch and
Matzke 2000b, character 77).
Character 200 Humerus – anterior flange: (0)
absent (1) present (modified from Motani 1999c,
character 53).
Character 201 Humerus – anterior flange size: (0)
large, complete (1) reduced proximally (modified
from Motani 1999c, character 53). See character
200.
Character 202 Humerus – relative width at mid-
shaft, exclusive of anterior flange: (0) more than
twice as proximodistally long as anteroposteriorly
wide (1) approximately equidimensional (Motani
1999c, character 54).
Character 203 Humerus – dorsal trochanter: (0)
none or incipient (1) well-developed (Maisch and
Matzke 2000b, character 78).
Character 204 Humerus – protruding deltopectoral
crest: (0) absent (1) present (modified from Fischer
et al. 2011, character 31; after Fischer et al. 2013,
character 39).
Character 205 Humerus – development of protrud-
ing deltopectoral crest: (0) normal (1) large, match-
ing the dorsal trochanter in height, and bordered by
concave areas (modified from Fischer et al. 2011,
character 31; after Fischer et al. 2013, character
39). See character 204.
Character 206 Humerus – relative anteroposterior
width in dorsal view, excluding dorsal and ventral
processes: (0) distal end wider than proximal (1)
approximately equal or proximal end wider than
distal (Fischer et al. 2011, character 32).
Character 207 Humerus – plate-like dorsal ridge:
(0) absent (1) present (Druckenmiller and Maxwell
2010, character 31).
Character 208 Humerus – position of distal facets:
(0) not terminal (1) terminal (modified from Motani
1999c, character 52).
Character 209 Humerus – relative size of radial
and ulnar facets: (0) radial facet is larger than the
ulnar facet (1) radial and ulnar facets approxi-
mately equal size (modified from Motani 1999c,
character 52). See character 208.
Character 210 Humerus – separation of radial and
ulnar facets: (0) continuous (1) separated by notch
(Maxwell 2012, character 36). This is coded as
inapplicable in taxa where the radial and ulnar fac-
ets are separated by e.g. the intermedial facet.
Character 211 Humerus – ulnar facet deflected
posterodistally, distal facing radial facet: (0) absent
(1) present (Fischer et al. 2012, character 34).
Character 212 Humerus – tuberosity at the antero-
distal extremity: (0) present (1) absent, acute angle
(Fischer et al. 2013, character 44).
Character 213 Humerus – anterodistal facet for
sesamoid: (0) absent (1) present (Motani 1999c,
character 57).
Character 214 Humerus – posterodistal facet for
sesamoid: (0) absent (1) present (Druckenmiller
and Maxwell 2010, character 36).
Character 215 Humerus-intermedium – contact:
(0) absent (1) present (Fernández 2007a, charac-
ter 16).
Character 216 Forelimb – epipodial and metapo-
dial shape: (0) flattened and plate-like (1) strongly
thickened (Maisch and Matzke 2000b, character
94).
Character 217 Forelimb – notching of anterior face
on leading edge elements [in adults]: (0) present
(1) absent (Fischer et al. 2011, character 37).
Character 218 Forelimb – notching of posterior
face on trailing edge elements [in adults]: (0)
absent (1) present.
Character 219 Forelimb – number of postaxial
‘complete’ accessory digits: (0) none (1) one (2)
two or more (Fischer et al. 2011, character 38).
This character is treated as ordered. See also
characters 217, 283 and 284.
Character 220 Epipodials – relative size of anterior
and posterior element: (0) radius/tibia much larger
than ulna/fibula (1) equal in size (modified from
Nicholls and Manabe 2001, character 24).
Character 221 Epipodials – interosseous space
between ulna and radius: (0) present (1) small fora-
men (2) absent (Sander 2000, character 87).
Character 222 Radius – proximodistal length to
anteroposterior width: (0) longer than wide (1)
wider than long (Motani 1999c, character 61).
Character 223 Ulna – posterior margin: (0) con-
cave (1) notched (2) straight or convex (modified
from Motani 1999c, character 62). See character
199.
Character 224 Ulna – anteroposterior width: (0)
proximal end narrower than distal (1) about equal
widths (Maisch and Matzke 2000b, character 87).
Character 225 Ulna – shape of the posterior sur-
face: (0) rounded or straight and nearly as thick as
the rest of the element (1) concave with a thin,
blade-like margin (Fischer et al. 2012, character
36, 2013, character 45).
Character 226 Manual pisiform: (0) present (1)
absent (Motani 1999c, character 67).
Character 227 Manual pisiform 2 (neomorph): (0)
absent (1) present (Jiang et al. 2006, character
20).
Character 228 Intermedium: (0) present (1) absent
(modified from Motani 1999c, character 66).

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41
Character 229 Intermedium-ulnare – relative size:
(0) ulnare larger than intermedium (1) ulnare
smaller than intermedium (modified from Motani
1999c, character 66). See character 228.
Character 230 Intermedium – location: (0) distal to
the ulna (1) between radius and ulna (modified
from Fernández 2007a, character 19).
Character 231 Intermedium – shape: (0) as wide
or wider than long (1) longer than wide (modified
from Jiang et al. 2006, character 22).
Character 232 Intermedium – proximal shape: (0)
straight or notched (1) pointed (modified from Jiang
et al. 2006, character 22).
Character 233 Intermedium – distal edge shape:
(0) angular (1) flattened (Maxwell 2010, character
27).
Character 234 Intermedium – number of digits
directly supported: (0) one (1) two (2) three (modi-
fied from Fischer et al. 2011, character 40). The
intermedium must have substantial distal facets
present for articulation with distal carpals, or con-
tact a distal carpal over at least 30% of its proximal
surface for a digit to be considered to be sup-
ported.
Character 235 Intermedium – size of distal facets:
(0) subequal (1) one much larger than the other(s)
(modified from Maxwell 2012, character 43).
Character 236 Ulnare – number of distal facets:
(0) primarily supporting a single digit (1) a posteri-
orly oriented facet for articulation with metacarpal V
at least half the length of the facet for mcIV (Max-
well 2012, character 44).
Character 237 Distal carpal – number: (0) five (1)
four (2) three (3) two (modified from Sander 2000,
character 92). This refers only to ‘true’ distal car-
pals, and not accessory elements in the distal car-
pal row (after Motani 1999a).
Character 238 Distal carpal 1-metacarpal V – rela-
tive size: (0) much smaller (1) similar size or larger
(modified from Maisch and Matzke 2000b, charac-
ter 95). This may be coded as inapplicable if either
element is not present.
Character 239 Distal carpals 2–3-distal carpal 5 –
relative size: (0) much smaller (1) of comparable
size (Maisch and Matzke 2000b, character 96).
Character 240 Distal carpal 4-metacarpal V – rela-
tive size: (0) much smaller (1) comparable in size
or larger (Maisch and Matzke 2000b, character
100).
Character 241 Manual digits – number of ossified
elements in the metacarpal row: (0) four or fewer
(1) five or more (Maxwell 2012, character 45).
Character 242 Manual preaxial accessory digit: (0)
absent (1) present (Fischer et al. 2011, character
39).
Character 243 Manual digit V reduction: (0) none
(1) reduced to small floating elements (modified
from Fischer et al. 2013, character 55). The
absence of digit five is removed from this character
as it is coded by the loss of metacarpal V (charac-
ter 247).
Character 244 Manual metacarpal I: (0) present
(1) absent (modified from Motani 1999c, character
68).
Character 245 Manual metacarpal I – shape: (0)
elongate (1) semilunate or rounded (modified from
Maisch and Matzke 2000b, character 97).
Character 246 Manual metacarpals II–IV – shape:
(0) elongate cylinder (1) rounded (Maisch and
Matzke 2000b, character 98).
Character 247 Manual metacarpal V: (0) present
(1) absent (modified from Maisch and Matzke
2000b, character 99).
Character 248 Manual metacarpal V – posterior
margin: (0) convex (1) straight or concave (modi-
fied from Maisch and Matzke 2000b, character 99).
Character 249 Manual phalanges – maximum
number in a single digit: (0) five or less (1) six or
more (modified from Motani 1999c, character 77).
Character 250 Proximal manual phalanges –
shape: (0) elongate or hourglass-shaped (1) mostly
rounded (2) tightly packed rectangles/polygons
(modified from Maisch and Matzke 2000b, charac-
ter 102; after Fischer et al. 2011, character 42).
Character 251 Distal manual phalanges – shape:
(0) elongate (1) rounded (Maisch and Matzke
2000b, character 101).
Character 252 Manual digital bifurcation: (0)
absent (1) present in at least some individuals
(modified from Fischer et al. 2011, character 43).
Character 253 Pelvic girdle – size: (0) normal-
sized (1) moderately reduced (2) strongly reduced
(Sander 2000, character 103).
Character 254 Ilium – blade shape: (0) with thick
shaft (1) plate-like (2) narrow and styloidal (Motani
1999c, character 80).
Character 255 Ilium – anteromedial prominence:
(0) present (1) absent (Motani 1999c, character
81).
Character 256 Ischium-pubis – medial fusion: (0)
absent (1) present (modified from Maxwell 2012,
character 50).
Character 257 Ischium-pubis – lateral fusion: (0)
absent (1) present (modified from Maxwell 2012,
character 51).

MAXWELL & CORTÉS: REVISION OF HAUFFIOPTERYX
42
Character 258 Ischium and pubis – meet medially
in well defined symphysis: (0) present (1) strongly
convex medial margins (Maisch and Matzke
2000b, character 108).
Character 259 Ischium and pubis – relative size:
(0) pubis larger than ischium (1) similar size or
ischium larger (Maisch and Matzke 2000b, charac-
ter 107).
Character 260 Ischium or ischiopubis – shape: (0)
plate-like, flattened (1) rod-like (Fischer et al. 2011,
character 45).
Character 261 Ischium – medial edge expansion:
(0) great (1) little or none (Maxwell 2012, character
53).
Character 262 Ischium – acetabular contribution:
(0) greater than pubis (1) subequal with pubis
(Maxwell 2012, character 52).
Character 263 Pubis – obturator foramen: (0)
present (1) absent (modified from Motani 1999c,
character 84).
Character 264 Pubis – location of obturator fora-
men: (0) completely enclosed in pubis (1) mostly in
pubis but open on one side (2) part of obturator
fossa (Thorne et al. 2011, character 84).
Character 265 Pubis – distance between the obtu-
rator foramen[/incisure] and the pubic symphysis:
(0) closer to the glenoid than the pubic symphysis
(1) closer to the pubic symphysis than to the gle-
noid (2) obturator fossa open medially (modified
from Maisch and Matzke 2000b, character 110).
Character 266 Femur – relative proximodistal
length to anteroposterior width: (0) much (>2×) lon-
ger than wide (1) shorter and wider, with distinct
medial constriction (Sander 2000, character 110).
Character 267 Femur – prominent, ridge-like dor-
sal and ventral processes demarcated from the
head and extending up to mid-shaft: (0) absent (1)
present (Fischer et al. 2011, character 46).
Character 268 Femur – ventral process size rela-
tive to dorsal process: (0) smaller (1) same size or
larger, more prominent (Roberts et al. 2014, char-
acter 52).
Character 269 Femur – wide distal blade: (0) pres-
ent (1) absent, subequal proximal and distal widths
(Fischer et al. 2013, character 61).
Character 270 Femur – anterodistal facet for ante-
rior accessory epipodial element anterior to the
tibia: (0) absent (1) present (Fischer et al. 2011,
character 48).
Character 271 Femur – tibial facet size relative to
fibular facet: (0) larger (1) subequal (Maisch and
Matzke 2000b, character 112).
Character 272 Tibia – proximodistal length to
anteroposterior width: (0) longer than wide (1)
wider than long (Motani 1999c, character 90).
Character 273 Tibia – anterior margin: (0) concave
(1) notched (2) straight or convex (modified from
Motani 1999c, character 92). See character 199.
Character 274 Tibia – posterior margin: (0) con-
cave (1) notched (2) straight or convex (modified
from Motani 1999c, character 91). See character
199.
Character 275 Tibia – proximodistal length relative
to more distal elements: (0) approximately twice as
long (1) only slightly longer (Maxwell 2012, charac-
ter 55).
Character 276 Tibia and fibula – relative size: (0)
tibia larger than fibula (1) approximately equal (2)
tibia proximodistally and anteroposteriorly smaller
(Maxwell 2012, character 56).
Character 277 Tibia and fibula – proximal contact:
(0) absent (1) present (modified from Motani
1999c, character 88; after Maxwell 2012, character
57).
Character 278 Fibula – anterior margin: (0) con-
cave (1) notched (2) straight or convex (modified
from Maxwell 2012, character 59). See character
199.
Character 279 Fibula – position relative to femur:
(0) not fixed, mobile relative to the femur (1) much
posterior (2) about the same level (Motani 1999c,
character 93).
Character 280 Astragalus – position: (0) between
tibia and fibula (1) distal to tibia (Druckenmiller and
Maxwell 2010, character 48).
Character 281 Distal tarsals – number: (0) five (1)
four (2) three (Sander 2000, character 112).
Character 282 Pedal digit 1: (0) present (1) absent
(Motani 1999c, character 89).
Character 283 Hindlimb – notching on anterior of
leading edge metapodials: (0) absent (1) present
(Maxwell 2012, character 60). See also characters
217, 218 and 284.
Character 284 Hindlimb – notching on posterior of
trailing edge metapodials: (0) absent (1) present.
Character 285 Pedal postaxial accessory digit: (0)
absent (1) present (Fischer et al. 2011, character
50).
Character 286 Metatarsals – shape: (0) elongate
or hourglass-shaped (1) shortened and rounded
(2) polygonal (modified from Maisch and Matzke
2000b, character 118).
Character 287 Pedal phalanges – shape: (0) elon-
gate or hourglass-shaped (1) rounded (2) polygo-
nal (modified from Maisch and Matzke 2000b,
character 119). See character 286.

PALAEO-ELECTRONICA.ORG
43
APPENDIX 4.
Character by taxon matrix for phylogenetic analysis (.nex). (Available in zipped file at https://
palaeo-electronica.org/content/2020/3078-revision-of-hauffiopteryx.)