A New Rhamphorhynchid Pterosaur from the Upper Jurassic of Xinjiang, China, and the Phylogenetic Relationships of Basal Pterosaurs

Abstract

A new rhamphorhynchid pterosaur species, Sericipterus wucaiwanensis, gen. et sp. nov., is described from the Upper Jurassic part of the Shishugou Formation in the Xinjiang Autonomous Region of northwest China. Pterosaurs from this unit are the earliest and only records of pterosaurs in the Jurassic of northwest China. The individual specimen is one of the largest known among ‘rhamphorhynchoids,’ or non-pterodactyloid pterosaurs. The holotype comprises an associated skeleton of mostly disarticulated, largely three-dimensional material. Although partly crushed, the preservation in this specimen reveals morphology rarely seen in non-pterodactyloid pterosaurs. This includes a distinct cervical intervertebral articulation morphology that is proposed to be widespread among the non-pterodactyloids. The skull of this new specimen is most similar to that of other rhamphorhynchids, Angustinaripterus longicephalus and Harpactognathus gentryii, found in terrestrial deposits. A phylogenetic analysis of 18 non-pterodactyloid pterosaurs and the Pterodactyloidea places Sericipterus wucaiwanensis with these species within the Rhamphorhynchinae and a monophyletic Rhamphorhynchidae. Unlike previous phylogenetic analyses, the Dimorphodontidae is paraphyletic, the Campylognathoididae is polyphyletic, and the Anurognathidae is the sister group of the Pterodactyloidea. Sericipterus wucaiwanensis, Angustinaripterus longicephalus, Harpactognathus gentryii represent a clade of large pterosaurs that likely lived in the terrestrial settings in which they preserved.

Full text

Journal of Vertebrate Paleontology 30(1):163–187, January 2010
© 2010 by the Society of Vertebrate Paleontology
ARTICLE
A NEW RHAMPHORHYNCHID PTEROSAUR FROM THE UPPER JURASSIC OF XINJIANG,
CHINA, AND THE PHYLOGENETIC RELATIONSHIPS OF BASAL PTEROSAURS
BRIAN ANDRES,
*,1
JAMES M. CLARK,
2
and XU XING
3
1
Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06520, U.S.A., brian.andres@aya.yale.edu;
2
Department of Biological Sciences, George Washington University, Washington, D.C. 10024, U.S.A., jclark@gwu.edu;
3
Institute of Vertebrate Paleontology & Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China,
xu.xing@pa.ivpp.ac.cn
ABSTRACT—A new rhamphorhynchid pterosaur species, Sericipterus wucaiwanensis, gen. et sp. nov., is described from
the Upper Jurassic part of the Shishugou Formation in the Xinjiang Autonomous Region of northwest China. Pterosaurs
from this unit are the earliest and only records of pterosaurs in the Jurassic of northwest China. The individual specimen
is one of the largest known among ‘rhamphorhynchoids,’ or non-pterodactyloid pterosaurs. The holotype comprises an as-
sociated skeleton of mostly disarticulated, largely three-dimensional material. Although partly crushed, the preservation in
this specimen reveals morphology rarely seen in non-pterodactyloid pterosaurs. This includes a distinct cervical intervertebral
articulation morphology that is proposed to be widespread among the non-pterodactyloids. The skull of this new specimen
is most similar to that of other rhamphorhynchids, Angustinaripterus longicephalus and Harpactognathus gentryii, found in
terrestrial deposits. A phylogenetic analysis of 18 non-pterodactyloid pterosaurs and the Pterodactyloidea places Sericipterus
wucaiw anensis with these species within the Rhamphorhynchinae and a monophyletic Rhamphorhynchidae. Unlike previous
phylogenetic analyses, the Dimorphodontidae is paraphyletic, the Campylognathoididae is polyphyletic, and the Anurognathi-
dae is the sister group of the Pterodactyloidea. Sericipterus w ucaiwanensis, Angustinaripterus longicephalus, Harpactognathus
gentryii represent a clade of large pterosaurs that likely lived in the terrestrial settings in which they preserved.
INTRODUCTION
From 2001 to 2006, joint paleontological expeditions from
the Institute of Vertebrate Paleontology and Paleoanthropology,
Beijing, and The George Washington University, Washington,
D.C., surveyed the Junggar Basin of the Xinjiang Autonomous
Region, People’s Republic of China. The most productive fos-
sil vertebrate locality found during these annual expeditions has
been the Wucaiwan area in the eastern part of the Junggar Basin
(Fig. 1). Here, the remains of the basal tyrannosauroid Guanlong
wucaii (Xu et al., 2006b), ceratosaurs (Xu et al., 2009), a giant
theropod (Xu and Clark, 2008), the basal ceratopsian Yinlong
downsi (Xu et al., 2006a), the stegosaur Jiangjunosaurus jung-
garensis (Jia et al., 2007), tritylodonts, and multiple crocodylo-
morphs such as the ‘sphenosuchian’ Junggarsuchus sloani (Clark
et al., 2004a) were excavated from the Shishugou Formation.
Three pterosaur specimens have also been reported from the
same area and formation (Andres and Clark, 2005), the most
complete of which is described here.
Pterosaurs have already been reported from Xinjiang but, pre-
viously, were confined to the Lower Cretaceous Tugulu Group
(Young, 1964, 1973; Buffetaut, 1996; Maisch et al., 2004). These
include the species Dsungaripterus w eii Young, 1964, Noripterus
complicidens Young, 1973, and Lonchognathosaurus acutirostris
Maisch et al., 2004, which is likely an individual of Dsungaripterus
weii (B. Andres, pers. observ.). The pterosaur discoveries from
the Wucaiwan locality are the earliest and only record of Juras-
sic pterosaurs from Xinjiang and one of only a handful of Juras-
sic pterosaur localities from China. The new specimens include a
‘rhamphorhynchoid,’ or non-pterodactyloid pterosaur, that is de-
scribed here, an isolated wing phalanx from the upper part of the
*
Corresponding author.
Shishugou Formation, and a fragmentary pterodactyloid from the
lower part of the same formation.
Traditional classifications (e.g., Wellnhofer, 1978) divided
pterosaurs into two suborders: the primitive long-tailed “Rham-
phorhynchoidea,”and the derived short-tailed Pterodactyloidea.
The “Rhamphorhynchoidea” has been shown to be paraphyletic
with respect to the Pterodactyloidea (e.g., Howse, 1986; Kell-
ner, 2003; Unwin, 2003a). Therefore, in phylogenetic literature it
has been informally termed non-pterodactyloid pterosaurs (e.g.,
Jensen and Padian, 1989; Andres and Ji, 2006).
The Wucaiwan non-pterodactyloid pterosaur is described here,
named Sericipterus wucaiwanensis, gen. et sp. nov., compared
to the rhamphorhynchids, and its phylogenetic relationships to
the other basal pterosaurs are delineated. The new specimen
presents sufficient morphology to be described, diagnosed as
a new species, and used to help determine the phylogenetic
relationships of the non-pterodactyloid pterosaurs. It is com-
pared to the other taxa identified as rhamphorhynchids in the
phylogenetic analysis: Angustinaripterus longicephalus He et al.,
1983, from the Middle Jurassic of central China, Harpactog-
nathus gentryii Carpenter et al., 2003, from the Upper Jurassic
of Wyoming, Rhamphorhynchus muensteri (sensu Bennett, 1996)
and Scaphognathus crassirostris Wagner, 1861, from the Upper
Jurassic of Germany, Cacibupteryx caribensis Gasparini et al.,
2004, from the Upper Jurassic of Cuba, and Dorygnathus ban-
thensis Theodori, 1830, from the Lower Jurassic of Germany.
MATERIALS AND METHODS
The skeleton is described in anatomical position of the wings
outstretched laterally as they would be in flight. Therefore, what
might be termed the medial and lateral aspects of the more
proximal wing bones are instead referred to as the ventral and
dorsal aspects, respectively. The anatomical directions of mesial
163
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164 JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 30, NO. 1, 2010
FIGURE 1. Locality of Sericipterus w ucai-
wanensis holotype (arrow), upper part of
Shishugou Formation in the Wucaiwan area.
Viewed from the southeast.
and distal are used for orientating along the jaw margins as
opposed to anterior and posterior, respectively (e.g., Unwin,
2003a). Muscle scars in the appendicular skeleton are identified
with respect to the attachments recognized by Bennett (2003) in
Campylognathoides liasicus.
The procedure of calculating wingspans is taken from Bennett
(2001b), which consists of summing of the lengths of the forelimb
bones excluding the carpus and then multiplying by a factor of
two. The omission of the width across the pectoral girdle and
the carpus is intended to offset the flexures along the wing in the
total wingspan. This is a repeatable and conservative method to
calculate wingspans, which have tended to be reported as larger
in the literature.
The wings of Sericipterus are missing the wing metacarpals as
well as having incomplete radii/ulnae and third wing phalanges.
A minimum wingspan estimate of 1.73 m was calculated by
summing the lengths of the complete wing bones, the estimated
minimum length of the third wing phalanx, and the estimated
length of the missing radius/ulna and wing metacarpal. The left
and right third wing phalanges are missing their proximal and
distal ends, respectively, so that it is not possible to ascertain the
total length of these elements. The more complete of these two
phalanges, the left phalanx, is missing its proximal end, which
through comparison with the proximal expansion of right phalanx
would add a minimum of 30 mm to its length. The length of the
radius/ulna and the wing metacarpal were calculated from the av-
erage ratio of these bones to the humerus in Rhamphorhynchus
muensteri, the species most closely related to Sericipterus with a
completely preserved wing skeleton in the analysis. All measure-
ments were made using a pair of Mitutoyo calipers, accurate to
0.02 mm.
The results of 20 phylogenetic analyses of pterosaur intrarela-
tionships have been published at the time of acceptance, 15 with
published data matrices (Howse, 1986; Bennett, 1989, 1994, 2007;
Unwin, 1992, 1995, 2002, 2003a, 2003b; Unwin and L
¨
u, 1997;
Viscardi et al., 1999; Kellner, 2003, 2004; Maisch et al., 2004;
Wang et al., 2005, 2008; L
¨
u and Ji, 2006; Martill and Naish, 2006;
Andres and Ji, 2008; L
¨
u et al., 2008). Only eight of these analyses
have addressed the relationships of the basal pterosaurs. Char-
acters, codings, and terminal taxa from this previous work were
integrated into this analysis and were recoded as little as possible
to provide a consensus of previous work. Inapplicable character
states were reductively coded. In other words, characters depen-
dent on the presence of a particular state in another character
were coded as missing data for taxa in which the particular state is
absent (i.e., a character complex). Inapplicable states are marked
by a dash (–), which phylogenetic analysis programs treat the
same as missing data (Strong and Lipscomb, 2000). Parsimony
uninformative characters were omitted resulting in a list of 75
characters (Appendix 1). Eighteen non-pterodactyloid species
including Sericipterus w ucaiw anensis, the three outgroups used
by Wang et al. (2005), and a supraspecific taxon representing
the Pterodactyloidea were used as terminal taxa. The character
states for the Pterodactyloidea were obtained by optimizing the
characters of this analysis to the base of the Pterodactyloidea on
the topology recovered by Andres and Ji (2008). Characters with
ambiguous optimizations were coded as polymorphic for this
taxon.
The character matrix (Appendix 2) was analyzed using
PAUP
∗
4.0 b10 (Swofford, 2003) both with and without am-
biguous branch support (amb and amb− parsimony options,
respectively). Tree searches included a Branch-and-Bound
search and 10,000 random addition-sequence Tree-Bisection-
Reconnection heuristic searches. All characters were unordered
and equally weighted (Fitch optimality criterion). Bootstrap and
Bremer support values were generated using the same settings
as the heuristic parsimony analysis. Tree lengths and tree scores
were calculated in PAUP
∗
, and the index file for calculating
Bremer support values in PAUP
∗
was generated in MacClade
4.07 (Maddison and Maddison, 2005).
SYSTEMATIC PALEONTOLOGY
PTEROSAURIA Owen, 1842
RHAMPHORHYNCHIDAE Seeley, 1870
RHAMPHORHYNCHINAE SENSU Unwin, 2003a
SERICIPTERUS, gen. nov.
Type Species—Sericipterus wucaiw anensis, sp. nov.
Diagnosis—As for type and only species.
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ANDRES ET AL.—NEW RHAMPHORHYNCHID PTEROSAUR FROM XINJIANG 165
Etymology—The generic name is based on the Latin word ser-
icum (L.), meaning silk in reference to the ancient Silk Road that
passed through what is now the Xinjiang Autonomous Region,
and pteros (Gr.), meaning wing, a traditional ending for pterosaur
names.
SERICIPTERUS WUCAIWANENSIS, sp. nov.
(Figs. 2–6)
Holotype—IVPP V14725 (Institute of Vertebrate Paleon-
tology and Paleoanthropology, Beijing, People’s Republic of
China): an incomplete skeleton including a disarticulated skull;
partial mandible; at least 12 isolated teeth; partial vertebral col-
umn (six cervicals, nine dorsals, two sacrals); the right scapula
and coracoid; both humeri; the ends of the right ulnae and radii;
the distal end of the left ulna; a proximal manual phalanx; the left
first, right second, both third, and both fourth wing phalanges; an
ischiopubic plate; two metapodial elements, and a probable pedal
phalanx fragment.
Etymology—The specific name is derived from the Wucaiwan
area in which this pterosaur was found. In Chinese it means ‘five-
color bay’ and refers to the striking variegated colors of the rocks
in the area (Fig. 1).
Distribution—Alluvial facies of the Upper Shishugou Forma-
tion, between tuffs dated at 161.2 ± 0.2 Ma and 158.7 ± 0.3 Ma
(Clark et al., 2006), equivalent to the Oxfordian, Upper Jurassic;
Wucaiwan locality, eastern Junggar Basin, Xinjiang Autonomous
Region, People’s Republic of China.
Diagnosis—Largest rhamphorhynchid with a wingspan of at
least 1.73 m. Apomorphies in comparison with other non-
pterodactyloid pterosaurs: terminal rostral expansion includes
only two pairs of teeth; nasal process of the maxilla with T-shaped
cross-section; large, U-shaped quadratojugal has broad contact
with the ventral margin of the skull; large lateral processes of the
parietals abut the postorbital processes of frontals; low parietal
crest extending most of length of parietal; transverse crest at fron-
toparietal contact; scapula length subequal to coracoid; wing pha-
langes with oval cross-section twice as wide as deep; expanded
ends of first and second wing phalanges wider than twice their
mid-width; fourth wing phalanx slightly longer than second wing
phalanx; enlarged metatarsals with subterminal distal condyles.
DESCRIPTION
IVPP V14725 is a partial skeleton preserved over a one-half
by one-quarter-meter area and collected in a single field jacket
(Fig. 2). The specimen is disarticulated save for bones of the
braincase and the dorsal and sacral vertebral series. The speci-
men was removed from the surrounding matrix with the excep-
tion of the bones of the braincase and temporal region of the
skull for which full preparation would have undermined phys-
ical integrity of these elements. The quality of preservation of
the individual bones varies greatly over the specimen. It was
found on a deflated surface so that the skeletal elements are all
in some manner crushed, broken, or fractured; however, the tex-
ture of the bone is generally well preserved and most elements
are three-dimensional. This type of preservation is more typical
of pterosaur specimens recovered from terrestrial sediments, in-
stead of the thinly bedded lagerst
¨
atten that preserve the majority
of pterosaur specimens.
Ontogeny
This individual is considered to be an osteological sub-adult be-
cause most but not all of the elements known to fuse during on-
togeny of pterosaurs remain unfused in this specimen. Sutures are
not visible between some elements of skull whereas others have
become disarticulated. In the postcranium, the scapula and cora-
TABLE 1. Measurements of the skull elements of IVPP V14725 (in
mm).
Element Left Right
Preserved rostrum length >146.8
Preserved braincase length >54.0
Skull length anterior to external
naris
∼63.2
Skull height at anterior margin of
external naris
36.0
Skull maximum width ∼58.5
External nares length > 45.9 > 50.6
External nares height — 9.1
Antorbital fenestra length > 28.6 > 34.1
Antorbital fenestra height > 15.3 > 29.9
Tooth row length > 84.1
Mandible length > 113.2 > 146.4
— = missing element; > = preserved length; ∼= approximate.
coid, sacral ribs, and the extensor tendon process of the first wing
phalanx remain unfused. Some neural arches of dorsal vertebrae
are separated from their lateral lamina, suggesting incomplete fu-
sion between centra and the neural arches. However, sutures are
not visible on the more complete dorsal or any other vertebrae.
Skull
The skull of IVPP V14725 is preserved as two distinct accumu-
lations and approximately 18 isolated tooth fragments that could
represent a minimum of 12 distinct teeth (Figs. 2–4; Table 1). The
rostrum is detached from the posterior region of the skull and
split into left and right halves just distal to the tip of the rostrum
on the left side (Fig. 3). These have come to lie upon the right
jugal and the left quadrate, respectively. The preserved posterior
region of the skull includes the braincase, several of the tempo-
ral bones, and the right quadrate (Fig. 4), as well as most of the
right and the posterior half of the left mandible (Fig. 1). The skull
likely broke into anterior and posterior regions, and subsequently
the rostrum split into two halves with the jugal and quadrate com-
ing to lie between them. The degree of disarticulation of the skull
is unusual for pterosaurs and reveals aspects of the skull not nor-
mally visible. The nasal process of the left maxilla is the poste-
rior extent of the preserved rostrum, whereas the anterior extent
of the preserved braincase is the orbit dorsal margin. These two
extremities would flank the ascending process of the jugal. Sum-
ming the length of the preserved rostrum, braincase, and width
of the ascending process of the jugal provides a minimum skull
length estimate of about 210 mm. The missing portions of the
frontals, prefrontals, lacrimals, nasals, and maxillae would have
to occupy only five mm for this skull to be larger than the previ-
ously largest known non-pterodactyloid skull, present in Dimor-
phodon macronyx Buckland 1829 (Wellnhofer, 1978).
Rostrum—The two halves of the rostrum were found lying on
their lateral surfaces (Fig. 2). They are highly fractured, espe-
cially at their posterior ends where they have been eroded. Col-
lectively, they preserve the anterior ends of the external narial
and antorbital fenestrae, jugal and nasal processes of the max-
illae, maxillary process of the left jugal, and the premaxillary
bar.
The left rostral fragment is more complete than the right and
was found associated with part of the right jugal (Fig. 3AB). It
includes the premaxillary bar, the anterior-most end of the right
half of the rostrum, and the anterior end of the maxillary process
of the left jugal. The left half of this fragment preserves the an-
terior portions of the left external naris, antorbital fenestra, the
jugal and nasal processes of the maxilla, and up to four alveoli. A
small, attached fragment of the right rostrum preserves the first
two right alveoli. The anterior end of the maxillary process of
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166 JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 30, NO. 1, 2010
FIGURE 2. Sericipterus w ucaiw anensis, gen. et sp. nov. (IVPP V14725). A, photograph; B, line drawing illustrating the arrangement of skeletal
elements as they were collected. Teeth are not labeled. Abbreviations: aof, antorbital fenestra; bc, braincase; co, coracoid; cv, cervical vertebra; d,
dorsal vertebra; etp, extensor tendon process of the first wing phalanx; fXdY, phalanx X of digit Y; h, humerus; ip, ischiopubic plate; j, jugal; m,
mandible; ma, maxilla; mp, manual phalanx; mt, metatarsal; n, external naris; na, nasal; oc, occipital condyle; pp, pedal phalanx; q, quadrate; qj,
quadratojugal; ra, radius; ri, ribs; ro, rostrum; s, sacral vertebra; sc, scapula; sq, squamosal; su, surangular; u, ulna; X.l, left element; and X.r, right
element. Teeth are not labeled. Scale equals 10 cm.
the left jugal was found articulated with the left maxilla but was
removed in Figure 3. The right rostral fragment is less crushed
and preserves presumably only the right maxilla (Fig. 3C). The
ventral margin of the external naris, the anterior end of the antor-
bital fenestra, and the nasal process of the maxilla that separates
these two openings dominate the preserved morphology. A skull
fragment located between the halves of the rostrum is identified
as the right nasal (Fig. 2).
The preserved portions of the anterior skull outline an elon-
gate rostrum. The premaxillae are fused along their preserved
lengths. The anterior tip of the skull bears a laterally compressed
rostral process. This process projects anteriorly from the midline
of the skull and is missing its tip to reveal an elliptical cross-
section in anterior view. The preserved portion of the process is
rather short, has a depth twice its width, and does not seem to
taper. The process connects posteriorly with a low sagittal crest
extending along the dorsal midline of the rostrum. The crest ex-
tends for half a centimeter before it is broken off and continues
posteriorly as a broken base. Posterior to the rostral process, the
rostrum is not compressed and does not expand evenly towards
the jaw articulations as in most pterosaurs. In dorsal and ventral
views, the jaw margins can be seen to rapidly increase in width to
the second alveolus forming an approximate 70
◦
angle with their
anterior end (Fig. 3D). This is the extent of the preservation on
the right side of the tip of the rostrum, but on the left side this ex-
pansion is immediately followed by a concave lateral jaw margin
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ANDRES ET AL.—NEW RHAMPHORHYNCHID PTEROSAUR FROM XINJIANG 167
FIGURE 3. Photograph and drawing of the rostral region of Sericipterus w ucaiwanensis, gen. et sp. nov. (IVPP V14725). A, left rostral fragment in
lateral view; B, left rostral fragment in medial view; C, right maxillary fragment in medial view; D, tip of rostrum of left rostral fragment in ventral
view. Abbreviations: aj, ascending process of the jugal; aof, antorbital fenestra; j, jugal; jm, jugal process of maxilla; l, left alveolus; L, left tooth; mj,
maxillary process of the jugal; mm, medial process of the maxilla; n, external naris; nf, medial flange on nasal process of the maxilla; nm, nasal process
of the maxilla; oj, lower orbital bar on the jugal; pb, premaxillary bar; r, right alveolus; rr, rugose ridge; R, right tooth; rc, rostral crest; X.l, left element;
X.r, right element. Scale equals 5 cm.
FIGURE 4. Photograph and line drawing of the temporal and occipital regions of Sericipterus wucaiwanensis, gen. et sp. nov. (IVPP V14725), in A,
dorsal; B, ventral view; and photographs of the C, right; D, left quadrate in anterior view. Abbreviations: aj, ascending process of the jugal; f, frontal;
fo; foramen; j, jugal; lp, laterosphenoid and prootic region; oc, occipital condyle; op, opisthotic; pcr, parietal crest; pf, pneumatic foramen; pn, palatine;
pr, fused parietals; qj, quadratojugal; qq, articular facet for quadratojugal on the quadrate; so, supraoccipital; sq, squamosal; su, sulcus; t, tooth; X.l,
left element; X.r, right element. Stippled regions represent matrix or matrix covered bone. Dashed lines represent the break between the left jugal
and the ascending and maxilla processes of the jugal. Scale equals 5 cm.
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168 JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 30, NO. 1, 2010
FIGURE 5. Photographs of the cervical vertebrae in Sericipterus wucai-
wanensis, gen. et sp. nov. (IVPP V14725). A, cervical 3; B, cervical 5; C,
cervical 7; D, cervical 8; in i, anterior; ii, posterior; iii, right lateral; iv, ven-
tral; v, left lateral; and vi, dorsal view. Abbreviations: ac, anterior cotyle;
di, diapophysis; ep, epipophysis; lt, lateral tubercle; ns, neural spine; pa,
parapophysis; pc, posterior condyle; pf, pneumatic foramen; pl; postlat-
eral projection of centrum; vk, ventral keel of centrum. Scale equals 2 cm.
denoting a constriction in the skull posterior to an expanded tip
of the rostrum.
It is difficult to discern the width of the skull posterior to the
rostrum. The less crushed right maxilla is mediolaterally broad
and has its nasal process dorsomedially oriented, indicating that
the skull was rather broad at this region. All of the teeth pre-
served in the specimen curve along an axis perpendicular to
the long axis of their cross-sections with the exception of the
first tooth-pair. The alveoli and in situ teeth in the jaw margins
indicate that this long axis is the mesiodistal axis as in other
pterosaurs. To accommodate the occlusion of this lingually curv-
ing dentition, the jaw margins would have to incorporate some
lateral orientation. Therefore, the teeth must have been directed
laterally to some degree but the exact angle is not known. The
alveoli project from the jaw margin, tracing a sinuous outline.
The premaxillae and maxillae apparently do not contribute to the
palate.
While being prepared, the premaxillary bar of IVPP V14725
was shifted slightly dorsally, giving the skull the higher posterior
outline seen in Figure 3. The premaxillary bar is fragmented and
may represent the disassociation of the left and right premaxillae
from one another in this region. The anterior part of the external
naris is preserved in both halves of the rostra. It is a remarkably
elongate, anteriorly inclined, and narrow opening. Its dorsal and
ventral margins are nearly straight and parallel to one another.
The rounded anterior- and ventral-most margin of the naris lies
well above the ventral margin of the antorbital fenestra. The an-
torbital fenestra is a much deeper opening with a larger, more
rounded anterior margin.
The contact between the premaxillae and maxillae is not visi-
ble in medial or lateral view and they are likely fused. On both
halves of the rostrum, the nasal process of the maxilla is nearly
straight and inclined about 30
◦
from the horizontal. This process
is T-shaped in cross-section due to a flange extending along the
medial aspect of this process (Fig. 3). The contact surface on the
left maxilla for the jugal is preserved, indicating these bones were
not fused. At this contact, the maxillary process of the jugal is
directed anterodorsally to extend over the jugal process of the
maxilla (removed in Figure 3). The contact surface on the maxilla
curves anteromedially to reach the anterior margin of the antor-
bital fenestra on its medial aspect.
On the medial aspect of both maxillae, a flat shelf of bone ex-
tends posteroventrally from the anterior end of the antorbital
fenestra orthogonal to the surface of the maxilla proper. This
can be seen best on the right maxilla (Fig. 3C), whereas on the
left half it remains as a broken process near the base of the
nasal process of the maxilla and has been shifted laterally into
the antorbital fenestra. This shelf contacts the medial flange on
the nasal process forming an internal fossa, presumably hous-
ing a paranasal diverticulum (Witmer, 1997), at the anterior mar-
gin of the antorbital fenestra. A rugose ridge extends anteriorly
under the external naris from this point. This shelf tapers pos-
terolaterally and somewhat resembles pterosaur palatines in this
manner. However, this would imply both a more dorsal position
and greater inclination for the palatines than is seen in other
pterosaurs. In addition, these elements do not seem to be sep-
arate bones from the maxillae. These shelves are termed the me-
dial processes of the maxilla. They may be the original maxillary
contributions to the palate but have subsequently been displaced
dorsally due to the posterior expansion of the palatines, diagnos-
tic for pterosaurs (Romer, 1956).
The midsection of the right jugal was found lying under the left
rostral fragment and was left attached to its medial surface during
preparation (Fig. 3A–B). The maxillary process, ascending pro-
cess, and the lower bar of the orbit are present, but incomplete.
These processes are perpendicular to one another. In addition,
the jugal proper is missing a piece of its ventral margin at the
junction of these processes and interrupting an otherwise straight
ventral margin in this region. On the lower orbital bar of the
jugal, a crescentic articular facet curves anteroventrally along the
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ANDRES ET AL.—NEW RHAMPHORHYNCHID PTEROSAUR FROM XINJIANG 169
FIGURE 6. Photographs of the appendicular elements of Sericipterus wucaiw anensis, gen. et sp. nov. (IVPP V14725). A, right scapulocoracoid in
lateral view; B, proximal end of right radius in anterior view; C, proximal end of right ulna in anterior view; D, distal end of left ulna in anterior
view; right humerus in E, ventral, F, dorsal, and G, proximal view; H, left first wing phalanx in dorsal view without extensor tendon process; I, right
second wing phalanx in dorsal view; J, distal end of left third wing phalanx in dorsal view; K, proximal end of right third wing phalanx in dorsal view;
L, proximal end of left fourth wing phalanx in dorsal view; M, right fourth wing phalanx in dorsal view; and metatarsal A in N, lateral, O, dorsal P,
proximal, and Q, distal view. Abbreviations: ap, acrocoracoid process; co, coracoid; dc, dorsal condyle; dco, dorsal cotyle; dp, deltopectoral crest; ect,
ectepicondyle; gf, glenoid fossa; gr, groove; hh, humeral head; ms, muscle scar; nf, nutrient foramen; pf, pneumatic foramen; ppr, posterior process; sa,
sternal articulation; sc, scapula; tub, tubercle; uc, ulnar crest; vco, ventral cotyle. Scale equals 5 cm.
posterior aspect of a short dorsal process and onto the medial
aspect of the jugal. The lateral margin of this short dorsal pro-
cess is not confluent with the lateral margin of the jugal proper,
which is damaged and likely constituted part of the posterior ex-
pansion of the jugal. If so, the short dorsal process would be part
of the anterior margin of the posterior expansion. The medial
facet likely is the contact for the pterygoid or ectopterygoid and
would indicate that the maxilla did not extend this far posteri-
orly along the medial side of the jugal. A similar condition has
been reported in Pteranodon where a small dorsal process lies
just anterior to the ectopterygoid contact with the jugal (Bennett,
2001a).
An isolated bone lying between the two halves of the rostra
is identified as the right nasal (Fig. 2). It is an elongate, wedge-
shaped bone with long and short edges separated by the margin of
an oval fenestra on one end. These edges have a slight sinusoidal
outline. If this identification is valid, then the long edge would
correspond to the contact between the left and right nasals, and
the free margin would correspond to the posterior margin of the
right external naris. The overall shape of this bone also resem-
bles the palatine of pterosaurs. However, the palatine contacts
a fenestrae, the internal naris, posteriorly and not on one of the
convergent edges as in this bone.
Among non-pterodactyloid pterosaurs, a midline process at
the anterior tip of the rostrum can only be seen as present
in Rhamphorhynchus, Angustinaripterus, and Harpactognathus.
These processes are elliptical in cross-section in Sericipterus
and Angustinaripterus, but triangular in Rhamphorhynchus
and Harpactognathus. In Sericipterus, Angustinaripterus, and
Harpactognathus, this rostral process is laterally compressed and
connects posteriorly to a low premaxillary sagittal crest, collec-
tively labeled a rostral crest in Figure 3. The posterior extent
of the sagittal crest is not preserved in any of these pterosaurs.
Premaxillary sagittal crests are widespread among pterodacty-
loids. They are also reported in the non-pterodactyloids Austri-
adactylus cristatus (Dalla Vecchia et al., 2002) and Raeticodacty-
lus filisurensis (Stecher, 2008), but these crests are much higher
and have a straight anterior margin in these species. Rostral ex-
pansions are reported here in Sericipterus and the other non-
pterodactyloids, Angustinaripterus and Harpactognathus. Rostral
expansions are present in some ctenochasmatid (Unwin, 2002)
and in the anhanguerid pterodactyloids (Campos and Kellner,
1985; Bakhurina and Unwin, 1995; Unwin, 2003a). The rostral
expansions in the non-pterodactyloids differ in their relative size;
Sericipterus incorporates two pairs of teeth, Angustinaripterus has
three pairs, and Harpactognathus has four pairs of teeth in its
expansion. These three pterosaurs also share a sinuous den-
tal margin, formerly listed as a diagnostic character of
Harpactognathus by Carpenter et al. (2003). Sericipterus and the
other rhamphorhynchines (sensu Unwin, 2003a) have elongate,
parallel-sided external nares. Other non-pterodactyloids have
more triangular external nares that, even when elongate and an-
teriorly inclined, maintain a flat base and a concave ventral mar-
gin. An antorbital fenestra with a ventral margin situated below
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170 JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 30, NO. 1, 2010
the external nares is present in all rhamphorhynchids identified
in the current phylogenetic analysis.
The condition of a T-shaped cross-section for the nasal process
of the maxilla cannot be assessed in many pterosaurs. However,
disarticulated maxillae in Campylognathoides, Dorygnathus, and
Dimorphodon; fortuitous breaks in Harpactognathus and An-
gustinaripterus; and CT radiology of Rhamphorhynchus (CMNH
11434) indicate that it is absent in these taxa (B. Andres, pers.
observ.) and therefore an apomorphic condition for Sericipterus.
Harpactognathus has a similar but distinct condition in that the
nasal process of its maxilla is dorsally thickened. A similar situ-
ation occurs with assessing the condition of the contact between
jugal and the maxilla. A jugal that spirals around the maxilla to
reach the medial aspect of the jaw margin as in Sericipterus can
be observed in some pterodactyloid species (e.g., Dsungaripterus
weii) (B. Andres, pers. observ.)). However, the distribution of
this feature among the non-pterodactyloids is not known because
the three-dimensional preservation required to assess this mor-
phology is rare among these taxa. Shelf-like palatal processes on
the maxilla can be seen in Angustinaripterus, but further distribu-
tion of this feature is not known.
Braincase and Temporal Region—The posterior region of the
skull of IVPP V 14725 was preserved lying on its dorsal sur-
face under the mandibles and right coracoid (Fig. 2). The brain-
case, frontals, fused parietals, portions of the left jugal, left
squamosal, right quadrate, right quadratojugal, and possibly one
of the palatines are present (Fig. 4). This region has been greatly
fractured and crushed dorsoventrally so that identification of the
other fragments and their margins is not possible, but these pre-
sumably belong to the missing palatal and temporal bones. In
general, the cranium fractured through the supraoccipital with
the other bones of the occiput rotated forward and the ventral
braincase being dorsally displaced into the portion of the cra-
nial cavity formed by the frontals. This left a small dorsal portion
of the supraoccipital and parietals extending further backwards
than the rotated occiput, visible as a small, rectangular flange in
Figure 4.
The identifiable elements of the chondrocranium are largely
limited to the bones of the occiput. In ventral view, the brain-
case narrows anteriorly from the occiput to where it is obscured
by the frontals. The prootics and laterosphenoids presumably oc-
cupy this region and would include some of the fragments in this
area, but their margins are not discernable. The occipital condyle
is semicircular in cross-section with a slight neck and is appar-
ently comprised only of the basioccipital. A slight groove ex-
tends along the otherwise flat dorsal flat margin of the condyle.
A small piece of the right half of the condyle has become dis-
placed slightly along a crack that extends through the region.
Short lateral flanges attach to the sides of the condylar neck.
Similar structures were identified as the exoccipitals in Rham-
phorhynchus by Wellnhofer (1975). The left example of these
two flanges has been detached and rotated, but no sutures are
visible on either side to confirm that these are separate bones.
The basioccipital is broken off ventrally at an apparent constric-
tion in this bone leaving no trace of the basisphenoid. The ven-
tral preserved end of the basioccipital is flanked laterally by two
foramina, the ‘foramen ovale’ of Wellnhofer (1975) (Fig. 4B).
However, these openings do not correspond to the fifth nerve
opening between the prootics and laterosphenoids that is termed
the foramen ovale in other taxa. They may be comparable to
the subcondylar recess of theropods such as tyrannosaurids (Wit-
mer, 1997). The opisthotics form large plate-like structures with
round lateral margins and are missing their squamosal contacts.
The left paroccipital process is more complete, extending out be-
neath the posterolateral process of the parietal to the region of
the squamosal contact. The opisthotics contact the parietals dor-
sally and wrap around the ‘foramen ovale’ ventrally. The foramen
magnum is relatively small and semicircular. It has a thickened
dorsal rim formed laterally by the opisthotics and dorsally by the
supraoccipital. The supraoccipital is rather small and has a low
midline ridge.
The preserved skull roof in this region includes the frontals
and parietals (Fig. 4A). The frontals and parietals are unfused to
each other and are oriented coplanar to one another. The large
frontals dominate this region of the skull and are complete save
for the missing tips of their anterior and postorbital processes. A
midline dorsal notch in the anterior margin of the frontals is pre-
sumably the contact for the premaxillary. The nasals do not ex-
tend posteriorly as processes in pterosaurs. The frontals contact
the parietals along a broad, posteriorly convex transverse crest.
The frontals have a nearly flat dorsal surface that extends lat-
erally behind the large orbits as wide postorbital processes. In
ventral view, the cristae cranii are broad and have ventrolaterally
facing surfaces.
The fused parietals are much smaller relative to the frontals but
still meet along the midline of the skull to exclude the frontals
from contacting the supraoccipital, unlike the reconstruction of
Rhamphorhynchus by Wellnhofer (1975). The parietals are dor-
sally arched above the braincase forming laterally sloping sides
for the medial walls of the supratemporal fenestrae between the
lateral and posterior processes of the parietal. A sizable distance
between the posterolateral end of the parietal and the postor-
bital process of the frontal indicates that the supratemporal fen-
estra was large. A lateral process of the parietal abuts the postor-
bital processes of the frontals posteriorly, but is shorter and ter-
minates before it would contact the postorbitals. The fused pari-
etals bear a low, narrow sagittal crest. However, this crest does
not extend above the dorsal margin of the skull and is therefore
not equivalent to the parietal crests present in some pterodacty-
loid peterosaurs. This crest contacts the similar transverse crest
that extends along the frontoparietal contact. The posterior pro-
cesses of the parietals are tapered and oriented posterolaterally
to where they would contact the squamosals.
A bell-shaped bone lying next to the left squamosal process
of the parietal is identified as the left squamosal (Figure 4). Its
overall form is of a broken process with two concave margins ter-
minating in large, convex, laterally curving end. The only other
bone in the skull with a similar shape would be the postorbital,
which is more triradiate and has much narrower processes. If it
is the squamosal, the broken process would correspond to the
postorbital process, and the two concave margins as the ven-
tral and dorsal margins of the infratemporal and supratempo-
ral fenestrae, respectively. Because the more concave margin
would correspond to the infratemporal fenestra and this bone
curves slightly laterally, this element can be identified as the left
squamosal.
An adjacent element is identified as the right quadratojugal.
It is a rather large, U-shaped bone with tall anterior and poste-
rior ascending processes. These processes would broadly contact
the jugal and the quadrate. This bone traces the ventral margin
of the infratemporal fenestra, which would therefore be rather
large and have a round ventral margin. A raised edge traces
the medial margin of the ventral and posterior margins of this
bone. The anterior of the two ascending processes is straighter
and about twice the length of the more posterior process. The
lateral edge of this anterior process has been quite damaged.
The more posterior process forms a sharp, hooked end that
matches exactly a distinct anteriorly oriented facet on the lat-
eral margin of the quadrate (Fig. 4C). The hooked process is
all that remains of the left quadratojugal, which was found ly-
ing on top of the left quadrate and underneath the right maxilla
(Fig. 4D). On the medial surface of the anterior end of the ventral
margin is a narrow groove that may have articulated with a slen-
der process of the jugal. The quadratojugal would have a broad
contact with the ventral margin of the skull and exclude the ju-
gal from contacting the quadrate. The inclination of the posterior
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ANDRES ET AL.—NEW RHAMPHORHYNCHID PTEROSAUR FROM XINJIANG 171
hooked process indicates that the quadrate was relatively inclined
with respect to the ventral margin of the rostrum.
Lying between the anterior and posterior processes of the right
parietal is an elongate bone that is visible in dorsal and ventral
views of the braincase. Though poorly preserved, its elongate,
triangular outline and large size suggest that this is one of the
palatines.
On the dorsal aspect of the skull is an incomplete bone with a
greatly expanded end, a middle constriction, and a straight pro-
cess that has been broken off at its base but connects at a right
angle to the long axis of the rest of the bone. This bone is identi-
fied as the left jugal. The expanded end corresponds to the poste-
rior margin that would contact the anterior ascending process of
the quadratojugal. A process would have extended dorsally from
this posterior margin to contact the postorbital, but this has been
broken off at its base. The middle constriction corresponds to the
ventral-most margin of the orbit, and the elongate, broken pro-
cess would be the ascending process of the jugal. The exact orien-
tation of the ascending process cannot be determined. The bro-
ken base of the maxillary process is evident just ventral to the as-
cending process. The ascending process of the left jugal preserves
part of its dorsal-most expansion and possibly includes portions
of the lacrimal and/or prefrontal. This expansion would lie near
the skull roof so that taking the entire height of the preserved
jugal provides a minimum skull height estimate at the front of
the orbit of 51.5 mm. The posterior end of the jugal is expanded
ventrally. This ventral expansion is likely the posterior process of
the jugal found in other pterosaurs but oriented vertically in this
specimen. A large flat bone with two divergent processes lying on
the ventral aspect of the frontals is likely the posterior end of the
right jugal. This element is highly fractured and its identification
is not certain.
The right quadrate was found in contact with the right quadra-
tojugal, and the left quadrate was found underneath the right
rostral fragment in contact with the posterior end of the left
quadratojugal (Fig. 2, but removed in Fig. 3A–B). Both quadrates
are missing their dorsal ends but are otherwise well preserved
(Fig. 4C–D). The quadrates are anteroposteriorly compressed
and would have had very little exposure on the lateral surface
of the skull. This exposure is limited to the laterally offset lat-
eral condyle of the jaw articulation and the thin flange extend-
ing dorsally from its posterior margin. The flange forms an an-
teriorly oriented vertical groove to receive the posterior margin
of the quadratojugal. This facet is wider near its base, giving it
an overall squat, subtriangular shape. The rest of the lateral sur-
face is straight and recessed from what would be the lateral mar-
gin of the skull. The quadrates have well-developed obliquely
aligned, double condyles. The lateral condyle is well offset lat-
erally to the extent that the margins of the condyles do not over-
lap in anterior or posterior view. This is in contrast to the rela-
tive elongate shape of the condyles, whose long axis is more than
three times the length of the short axis. The condyles and the
strong sulcus that divides them are oriented 45
◦
anteromedially
from the sagittal plane. A small, presumably pneumatic, foramen
dives dorsally into the anterior aspect of the quadrate just lateral
to the quadrate midline and level with the dorsal termination of
the quadratojugal articulation. A sharp, anteromedially curving
process extends from the medial side of the left quadrate’s ven-
tral end. This process would presumably contact the pterygoid.
The quadrates are laterally thicker in cross-section. On the right
quadrate fragment, the lateral thickening shifts slightly medially
near the dorsal end so that the lateral edge becomes a flange dor-
sally. The medial margin is poorly preserved in both quadrates,
but can be seen to expand medially in the right quadrate to where
it would eventually contact the occiput.
The posterior aspect of the skull in non-pterodactyloids is ef-
fectively described from a single specimen of Rhamphorhynchus
(CMNH 11434, see Wellnhofer, 1975; http://www.digimorph.
org/specimens/Rhamphorhynchus
muensteri/). The occipital re-
gion of IVPP V 14725 largely agrees with Wellnhofer’s (1975)
reconstruction of Rhamphorhynchus, with the exception of a
much smaller supraoccipital and conversely larger parietals. The
supraoccipital therefore does not contact the frontals as recon-
structed by Wellnhofer (1975). The parietals have a significant
contact with the postorbital processes of the frontal, but are
still dwarfed by the frontals. Large, V-shaped quadratojugals are
reported in Dorygnathus (Padian and Wild, 2008) and recon-
structed in Parapsicephalus purdoni (Newton, 1888), but these
are much s horter anteroposteriorly and do not have a broad
contact with the ventral margin of the skull. Sericipterus, how-
ever, has longer, U-shaped quadratojugals that are as long as
they are tall, unlike the shorter quadratojugals in these other
taxa. Inclined quadrates are present in all but the basal-most
pterosaurs (Unwin, 2003b). Quadrates with oblique condyles sep-
arated by a posterolaterally oriented groove for articulation with
the mandible have been coded in some pterodactyloids such as
Quetz alcoatlus (Kellner and Langston, 1996) and termed helical
jaw joints (Eaton, 1910). They are also present in Sericipterus,
Dorygnathus, and Rhamphorhynchus. They cannot be observed
in Cacibupteryx and Angustinaripterus. An expanded posterior
end with a ventral process on the jugal is also present in Angusti-
naripterus. The midline sagittal crest on the parietals has not been
reported in non-pterodactyloids and is most similar to the blunt
sagittal crest coded in the anhanguerids (Kellner, 2003). A ridge
at the contact between the frontals and the parietals has been
reported in the pterodactyloid Gegepterus changi (Wang et al.,
2007).
Mandible—The right and left mandibular rami are present
though severely cracked and distorted (Fig. 2). The right ramus
is more complete but is twisted along its length and missing the
anterior end. This ramus is relatively straight, dorsoventrally low,
laterally compressed, and tapers slightly anteriorly. The remains
of two crushed alveoli are visible anteriorly in the right ramus,
but it is not known how many more teeth or how much more
of the mandible is missing. The left ramus is very poorly pre-
served and comprises only the posterior end of the ramus. The
adductor fossa, the cranial articulation, and a detached surangu-
lar are the only features that can be recognized on this element.
The adductor fossae, best preserved on the right, are elongate,
narrow, and elliptical in shape. The right fossa is about 53 mm
long and reaches nearly the entire length of the surangular to
terminate just anterior to the cranial articulation. The surangu-
lar is an elongate, thin bone positioned along the dorsal edge
of the posterior third of the preserved ramus. There is no dis-
tinct coronoid process. The prearticular extends from the cra-
nial articulation along the medial aspect of the ramus and ven-
tral to the fossa. The contact between the articular and sple-
nial is not discernable, but the splenial can be seen to extend
anteriorly from the fossa to terminate as a sharp wedge about
halfway down the preserved length of the mandible. The mar-
gins of the articular, angular, and posterior terminus of the den-
tary are not visible. The cranial articulation, best preserved on
the left, is gently concave dorsally and nearly square in outline.
The anterior edge of the articulation surface comprises robust
medial and lateral processes separated by a depression. The me-
dial process is the larger of the two, nearly twice as broad as the
lateral process, and about equal in breadth to the depression be-
tween them. These processes form the anterior margins of the
posterolaterally facing medial and lateral articular facets. A very
slight posterior buttress is present but is far enough posterior that
some anteroposterior movement of the mandible may have been
possible. A short, blunt, and triangular retroarticular process is
present.
Dentition—Eighteen tooth fragments that could at minimum
represent 12 teeth are preserved around the two skull regions.
They have smooth, glossy enamel that is stained blue in some
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172 JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 30, NO. 1, 2010
fragments. Most of the preserved teeth are isolated and consist
only of portions of the crowns. The right second and the left third
teeth remain in their alveoli, but the left third tooth is broken
off at its base. A tooth found lying on the right aspect of the left
rostral fragment next to the right tooth is identified as the right
third tooth based on its similar position, size, and cross-section as
the left third tooth, which was found in the largest rostral alveo-
lus (Fig. 3A–B). The largest isolated tooth in IVPP V 14725 is of
similar size and was found next to the proximal right ulna and ra-
dius (Fig. 2). The rostral alveoli increase in size to the third alve-
olus and then decrease in size distally. A tooth closely associated
with the tip of the rostrum (Fig. 2) is relatively less compressed
and similar in cross-sectional size to the first alveoli pair and is
most likely the left or right first tooth. The largest isolated tooth
is likely the largest tooth from the mandible and from a similar
position in the tooth row.
Alveolar spacing increases distally along the rostrum with the
distance between successive teeth always exceeding the diame-
ters in respective teeth. It is not known how far back in the skull
the tooth row extended. The tooth rows begin about three mm
behind the preserved tip of the rostral process where they lie
very close to the midline of the skull. The left half of the rostrum
preserves the mesial-most three alveoli, but the poorly preserved
outline of a fourth alveolus is likely present in the sinuous outline
of the jaw margin. An alveolus in a similar position on the right
maxillary fragment and second alveolus distal to it would bring
the tooth count along each side of the rostrum to at least five. If
the tooth row terminated under the antorbital fenestra as in other
Jurassic non-pterodactyloids, the tooth row could contain up to
seven teeth bringing the rostral tooth count to anywhere between
10 and 14, and the total tooth count to between 20 and 28 teeth
assuming a similar number of teeth present in the mandible. The
rostral tooth row extends past the anterior margin of the external
naris, or at least 40% of the minimum estimated skull length.
The rostral tooth row has raised borders on the mesial and dis-
tal edges of each alveolus giving the jaw margin a sinuous outline.
All alveoli are labiolingually compressed but are less compressed
mesially. The putative first tooth is the least recurved tooth in
the specimen, suggesting that the rostral teeth increase in curva-
ture to the third tooth. All other teeth are curved. The anterior-
most alveoli are inclined anteriorly about 30
◦
from the horizontal
plane, the left second about 45
◦
, the left third about 75
◦
, and right
fourth and fifth are subvertical.
The teeth are elongate, labiolingually compressed, and termi-
nate in sharp tips. Tooth lengths range from 24 to 53 mm, of which
half is erupted height. Short, isolated teeth are present so it is
most probable that the teeth decreased in height as well in diam-
eter distal to the third tooth. With the possible exception of the
mesial-most teeth, the teeth curve strongly lingually over their
entire erupted height at right angles to their mesiodistal long axis.
The roots are essentially straight and end in a small, circular nu-
trient foramen. The possible right third tooth has the largest cur-
vature in IVPP V14725. Its 10.4-mm ventral displacement along
its curvature indicates that the tip would have extended well ven-
tral to its alveolus. The mesial rostral teeth are partially later-
ally oriented, but it is most probable that all of the dentition had
some degree of lateral orientation to accommodate their curva-
ture. The mesial and distal edges of the teeth have thin, sharp
enamel keels extending along the length of the erupted tooth to
the tip. The distal keel is distinctly sharper, forming a long cutting
surface.
Compared to the 10–14 rostral teeth of Sericipterus, Angusti-
naripterus has 18 (He et al., 1983), Harpactognathus has at least
12 (Carpenter et al., 2003), Rhamphorhynchus has 17, Doryg-
nathus has 22, and Scaphognathus has 14 (Wellnhofer, 1978).
All non-pterodactyloids except for the anurognathids and Sor-
des pilosus have labiolingually compressed teeth. In Sericipterus,
all of the dentition is labiolingually compressed, whereas the
other r hamphorhynchids have teeth circular in cross-section at
the mesial end of their dentitions. Slender teeth are present
in all the rhamphorhynchids, which become more elongate in
the rhamphorhynchines. Procumbent and strongly curved teeth
are present in all rhamphorhynchines, but it is only in Rham-
phorhynchus that the entire dentition is procumbent. The mesial
and distal enamel keels with a sharper distal ridge, as in the
teeth of Sericipterus, have been reported in Rhamphorhynchus
(Wellnhofer, 1975) and seem to be to be present in Angustinar-
ipterus. In Sericipterus and Angustinaripterus, the teeth are di-
rected to some degree laterally and curve lingually, whereas the
teeth of the other rhamphorhynchids are upright and recurve pos-
teriorly. This lingual curvature of the teeth is perpendicular to the
direction of curvature from the rest of the non-pterodactyloids.
The cross-sectional long axes of the mesial-most teeth are not
parallel to the sagittal plane in Sericipterus. The similar position
of the mesial and distal enamel keels and mesiodistal long axis
of the teeth confirm that this is a novel direction of curvature as
opposed to the rotation of the teeth within their alveoli with re-
spect to other pterosaurs. Harpactognathus has laterally directed
alveoli, but because no teeth were found with the only known
specimen, it is not known if it shares a lingually curving, keeled
dentition.
Axial Skeleton
Remains of six cervical, nine dorsal, and at least two sacral ver-
tebra are preserved in the axial skeleton in IVPP V14725 (Figs.
2 and 5, Table 2). The six cervical vertebrae are very similar in
morphology and so represent cervicals 3 to 8, the longest series
of similarly shaped vertebrae within the cervical series. Cervical
8 is obscured and not shown in Figure 2. T he dorsal vertebrae
can be recognized as the posterior end of the dorsal series be-
cause of their contact with the pelvis. They are identified as dor-
sals 6 through 14. If the first vertebra that bears a large rib that
articulates with the sternum is identified as the first dorsal ver-
tebra as suggested by Bennett (2007), then non-pterodactyloid
pterosaurs typically have 13 to 15 dorsal vertebrae (modified
from Romer, 1956). Specimens of Anurognathus ammoni have,
however, been reported with as few as 11 or 12 dorsal vertebrae
(Bennett, 2007). The successive closest relatives to Sericipterus,
Rhamphorhynchus and Dorygnathus, have 14 (modified from
Wellnhofer, 1975) and 13 (after Padian and Wild, 2008) reported
dorsals, respectively. Because Rhamphorhynchus shares a closer
relationship, its dorsal count was used to assign positional iden-
tity, but it is possible that the original identities could be off by up
to two positions. The two sacrals are identified as sacrals 1 and 2
based on the unfused cotyle of the first sacral vertebrae and the
orientation of their sacral ribs. All vertebrae with recognizable
intervertebral articulations are procoelous. No sutures are visible
on any of the vertebrae. A number of elongate elements, aver-
aging about 2 mm in diameter, preserved adjacent to the humeri,
are likely parts of dorsal ribs based on their size, position, and
shape.
Cervical Vertebrae—The cervical vertebrae were found dis-
articulated and lying on their dorsal surfaces. These dorsal sur-
faces are very poorly preserved and so are not figured with the
exception of cervical 8 (Fig. 5). The cervical vertebrae in this
specimen have similar overall morphology but display variation
along the series that, along with the relative size of the pre-
served elements, were used to assign their positional identity.
Pterosaurs are interpreted as having nine cervicals (sensu Ben-
nett, 2007): an atlas-axis complex, five middle-series cervicals,
and two posterior-series cervicals. The two post-cervicals resem-
ble the vertebrae of the dorsal series to varying degrees across
pterosaur phylogeny. IVPP V 14725 preserves the mid-cervical
series and the anterior of the two post-cervicals so that only the
atlas-axis complex and cervical 9 are missing. Cervicals 3, 5, 7, and
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ANDRES ET AL.—NEW RHAMPHORHYNCHID PTEROSAUR FROM XINJIANG 173
TABLE 2. Measurements of the identified elements of the vertebral
column of IVPP V14725 (in mm).
Element Centrum length Mid-width
Cervical 3 23.3 15.1
Cervical 4 > 19.3 > 14.6
Cervical 5 24.5 18.7
Cervical 6 ? > 10.5
Cervical 7 > 17.1?
Cervical 8 22.5 25.2
Dorsal 5 > 8.87.4
Dorsal 6 14.35.7
Dorsal 7 14.66.1
Dorsal 8 14.77.3
Dorsal 9 14.36.2
Dorsal 10 14.07.2
Dorsal 11 12.77.5
Dorsal 12 ∼ 12.6 ∼ 7.0
Dorsal 13 ∼ 12.6 ∼ 5.3
Sacral 1 8.5 16.9
Sacral 2 8.2 17.8
? = cannot be measured; > = preserved length; ∼= approximate.
8 are the best preserved and are illustrated in Figure 5. Cervicals
4 and 7 each consist of only the posterior condyle and portions
of the neural arch. No cervical ribs can be identified. However,
distinct rib facets present on the cervical vertebrae indicate their
presence in the living organism. The size of the rib facets is sug-
gestive of elongate cervical ribs being present, but this cannot be
confirmed.
Cervical 3 differs from the other mid-cervical vertebrae in be-
ing relatively smaller and narrower (Fig. 5A). Though there is
variation in length along the mid-cervical series, these vertebrae
are subequal in length, ranging between 1.6 and 1.8 times the av-
erage length of preserved dorsal vertebra. Cervical 3 shares with
the other mid-cervicals a lateral, transverse crest extending from
the prezygapophyses to the postzygapophyses. A ventral lip ex-
tends along the lateral margin of the transverse crest at least an-
terior to the rib articulations. Posterior to the rib articulations
the transverse crest and postzygapophyses are too poorly pre-
served to resolve their morphology. Anteriorly, the ventral lip
of the transverse crest contacts the base of the prezygapophy-
seal articulation to form a small, deep fovea. In other vertebrae,
this pit may be filled with matrix and resemble a foramen, but
they are all identified as foveae here. The prezygapophyses bear
expanded, subcircular, nearly flat articular surfaces oriented an-
teromedially at an angle about 45
◦
from horizontal. The dorsal
aspect of cervical 3 is poorly preserved but the anterior end of
the neural s pine is preserved. The neural spine is a thin crest that
reaches the anterior margin of the neural arch, but its height and
posterior extent cannot be seen. The anterior margin of the dor-
sal laminae of the neural arch overhangs the anterior cotyle. The
anterior margins of both the neural arch and centrum bound a
triangular recess that houses a flat-bottomed neural canal. There
are no traces of lateral or a medial pneumatic foramina flanking
the neural canal. The anterior cotyle is a broad ellipse in ante-
rior view, but in ventral view it is a deep, semicircular crescent.
The anterolateral ends of the anterior cotyle form buttresses with
the bases of the prezygapophyses and the lateral laminae of the
neural arch. This is the position of the parapophysis that lies ven-
tromedial to its sister diapophyses on the transverse crest at the
base of the prezygapophysis. The left prezygapophysis is well pre-
served; it forms a broad anteromedially facing surface with only
a slight upward tilt as preserved. A narrow sulcus separates the
rib articulations, but no more of their shape can be resolved on
this vertebra. The rib articulations are at the widest point of the
centrum from which the centrum rapidly decreases in width to a
near constant width over its posterior half, giving the entire cen-
trum a T-shape in ventral view. The entire vertebra including the
posterior condyle is straight. At its widest, the centrum laterally
contacts the lateral neural arch, but posteriorly the lateral lami-
nae of the neural arch are positioned dorsally. This posterior lat-
eral surface is pierced by small, elliptical pneumatic foramina in
the region just anterior to the base of the postzygapophysis, one
on each side. These foramina lie in shallow lateral excavations of
the neural arch. The right side of cervical 3 has been damaged in
this region, making the foramina appear larger on this side. Just
posterior to the anterior cotyle, a flat-bottomed ventral keel ex-
tends posteriorly along the midline of the centrum, giving the cen-
trum an inverted triangle cross-section in this region. Posteriorly,
this ridge terminates at the intersection with a posteroventrally
oriented concave surface. This concave surface angles up to the
posterior condyle to form a posterodorsally oriented, ventrally
curved lip at its contact with the condyle. This lip is mirrored by
another ventrally curved lip at the dorsal margin of the condyle so
that the entire articular surface is an inverted crescent (Fig. 5A).
The entire posterior condyle resembles the saddle-shaped hete-
rocoelous articulation of birds. It differs from the avian condition,
however, in that the articular surface curves ventrally instead of
expanding at its lateral margins, and lacks a lateral lip, merging
instead with the lateral surface of the centrum.
Cervical 4 is preserved only as the posterior condyle of the cen-
trum and the lateral lamina of the left neural arch (Fig. 2). It bears
a distinct, elliptical lateral pneumatic foramen on the neural arch
in a similar position to that seen in the other mid-cervical ver-
tebrae. It is identified based on similarities in its morphology to
cervical 3 and the slightly larger size of the posterior condyle.
Cervical 5 is broadly similar to the previous cervicals, but
larger and better preserved (Fig. 5B). It is the longest vertebra
preserved in the specimen. The anterior margin of the neural
arch does not overhang the anterior cotyle and the thin neu-
ral spine does not reach this anterior margin. Rib articulations
are present and more visible than in cervical 3. The parapoph-
ysis is an elongate, concave, and semicircular articular surface.
The diapophysis is similar in shape except that it is laterally thin-
ner and forms a ventral emargination where is intersects the lip
of the lateral transverse crest. The ventral lip of the transverse
crest extends the entire distance from the prezygapophysis to the
postzygapophysis. No middle constriction is apparent in the lat-
eral margins of the transverse crests, the mid-sections of which
are straight. The zygapophyses project from these straight lat-
eral margins, with the postzygapophyses projecting more later-
ally than the prezygapophyses. The posterior condyle extends
well posterior to the postzygapophyses as in the other cervi-
cal vertebrae. In cervical 5, the posterior condyle has been bro-
ken at its based and shifted ventrally. Originally, the posterior
condyle would have pointed directly posteriorly as in the other
cervicals. The zygpapophyseal articulations are slightly laterally
compressed and more oval than on cervical 3. They are ro-
bust and inclined about 20
◦
from vertical, the prezygapophyses
facing slightly dorsally and the postzygapophyses facing slightly
ventrally. Distinct epipophyses are developed as processes that
overhang the dorsolateral margins of the postzygapophyseal ar-
ticular surfaces. A shallow groove extends around the base of the
epipophyses. The ventral keel is much thinner than in cervical
3. A posteroventral concave surface again separates the ventral
keel from the posterior condyle, but this surface does not form a
continuous ventral lip with the condyle. The dorsal lip is present,
but all that is present of the ventral lip is the right posterolat-
eral extension of the articular surface that connects with a ven-
trolateral ridge extending along the lateral margin of the ventral
concave surface. The left ventral part of the condyle is damaged,
but these projections were presumably paired structures as in the
succeeding vertebrae. The combined ridge and extension of the
posterior condyle are termed here postlateral projections of the
centrum. The lateral surfaces of the posterior condyle contact a
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174 JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 30, NO. 1, 2010
lateral sulcus extending anterior along the centrum from the pos-
terior condyle. The outline of the posterior condyle in ventral
view is still convex.
Cervical 6 is identified on the basis of its relative size and is the
most poorly preserved of the cervical vertebrae. It contains the
eroded portions of the posterior condyle, right prezygapophysis
and right postzygapophysis.
Cervical 7 is very poorly preserved with the exception of the
posterior condyle (Fig. 5C). This cervical was found under cervi-
cal 3 and presumably crushed by the overlying vertebra (Fig. 2).
No measurements could be taken on this vertebra. Besides the
condyle, the two prezygapophyses, and the left postzygapophysis
bearing a sharp epipophysis, can be recognized. The articular sur-
face of the slender left prezygapophysis faces dorsomedially at
an angle of about 45
◦
, unlike the more vertical zygapophyses ar-
ticulations in the preceeding cervicals. The posterior condyle is
quite distinct from that of the preceding vertebrae. There is a de-
pression immediately anterior to the posteroventral surface. The
postlateral projections are more robust, extending both ventrally
and posteriorly so that they would have contacted the succeed-
ing vertebra both ventrally and anteriorly. Though distinct, the
margins of these projections are confluent with their surrounding
surfaces so that no grooves, sulci, or any other linear structures
denote these as separate processes in any cervical. These projec-
tions give the condyle a biconvex shape in ventral and posterior
view. Deep sulci extend along the lateral faces of the centrum
from the condyle.
Cervical 8 is identified as a posterior-series cervical vertebra
because it is wider than the centrum length and resembles a dor-
sal vertebra more than any other cervical (Fig. 5D). Its identifi-
cation as the eighth in the cervical series is based upon the ab-
sence of small, closely situated prezygapophyses, the absence of
thin transverse processes, and the absence of an anteroposteri-
orly short centrum, all of which are found in the typical non-
pterodactyloid cervical 9 (B. Andres, pers. observ.). This verte-
bra was crushed obliquely so that the main portions of the neural
arch were shifted laterally to the right. The left prezygapophysis
has had its base broken off and shifted onto the ventral aspect of
the centrum. The postzygapophyses are missing, but if the iden-
tification as cervical 8 is correct, they would extend directly pos-
teriorly near the midline. A neural spine broken off at its base is
visible on the dorsal surface of the vertebra. This spine becomes
wider anteriorly. It is not known if this spine has a different shape
from the other vertebrae. The anterior margin of the neural arch
does not overhang the anterior cotyle. The large, widely spaced
prezygapophyses dominate this vertebra as in the eighth cervi-
cal of other pterosaurs. The transverse crests extend posteriorly
from the prezygapophyses at least as far as the mid-section of
the vertebra, but it cannot be determined whether they contact
the postzygapophyses. Rib facets in the same shape and position
as in cervical 5 can be seen on the ventral surface and are sepa-
rated by a narrow sulcus. No ventral ridge can be seen, though
the anterior half of the ventral aspect of the centrum has been
crushed. A posteroventrally oriented, concave surface cannot be
seen on the posterior end of the centrum. Stout postlateral pro-
jections form the entire ventral lip of the posterior condyle giv-
ing the posterior margin a rounded, biconvex appearance. This
is mirrored by more widely spaced projections of the dorsal lip
of the condyle. Distinct sulci extend along the lateral surfaces of
posterior centrum, halfway along which are lateral tubercles on
the ventral surface of the centrum that may be attachment sites
for collateral ligaments.
Overall, the cervical vertebrae of Sericipterus resemble larger
and more robust versions of the cervicals of other non-
pterodactyloid pterosaurs. Basal pterosaurs are typified by the
presence of similarly shaped and sized centra throughout the
mid-cervical series, distinct rib articulations, a square outline
to the neural arch in dorsal view, and a centrum that is wider
anteriorly. The rib articulations of Rhamphorhynchus are illus-
trated as a pair of sharp tubercles (Bonde and Christiansen, 2003;
Wellnhofer, 1975:fig. 4b). In Sericipterus, however, the rib artic-
ulations are distinct, concave facets. It is possible that the sharp
tubercles figured in Rhamphorhynchus are the broken off capit-
ula and tubercula of the cervical ribs. Hypapophyses have been
reported on the mid-cervical vertebrae of a specimen of Rham-
phorhynchus (Geological Museum of Copenhagen 1891.738)
(Bonde and Christiansen, 2003) at the position of the anterior ter-
mination of the ventral keel on the centra of Sericipterus. The hy-
papophyses of Rhamphorhynchus, however, are quite short and
do not extend posteriorly. Pneumatic foramina in the lateral lam-
ina of the neural arch are present in Rhamphorhynchus, Doryg-
nathus, and Sordes (B. Andres, pers. observ.). This last pterosaur
has foramina piercing the arch near the base of the prezygapoph-
ysis instead of near the base of the postzygapophysis, and so it
is possibly an independent development of cervical pneumatic-
ity. In their description of the pneumaticity present in MGUH
1891.738, Bonde and Christiansen (2003) reported two additional
pneumatic foramina on the lateral surface of the mid-cervical
centra, but this has not been confirmed in other specimens.
Dorsal Vertebrae—Portions of nine dorsal vertebrae are pre-
served in IVPP V14725. The total number of original dorsals is
not known and their identity is assigned on the basis of the dor-
sal vertebral count in Rhamphorhynchus. The preserved dorsal
series is 107.7 mm long. Averaging the lengths of the preserved
vertebrae and increasing to a total of 14 vertebrae would indi-
cate an entire dorsal series approximately 168 mm long. Most
of the dorsal vertebrae consist of preserved centra with varying
amounts of their neural arches remaining. They are rather elon-
gate and about twice as long as their widths or depths. Though
subject to crushing and distortion, these vertebrae are subequal
in length, varying less than two mm in length or width along the
series.
The first vertebra in the series, identified as dorsal 6, consists
of a posterior condyle with the neural arch missing, so that only
the concave internal aspect of the neural canal is visible. The
next dorsal is better preserved, though it has a large crack ex-
tending through its posterior end. This second vertebra has its
neural arch preserved, but the transverse processes are broken
off at their bases. The neural spine is a long, low, and thin crest.
The original spine was most likely higher and has been broken
off. The pre- and postzygapophyses are distinct, slim processes.
The prezygapophyses are more slender, elongate, curving, and
widely spaced than the postzygapophyses. There is a lateral fossa
between the base of the transverse process and centrum proper
but it cannot be seen to communicate with an internal space. The
succeeding vertebra, identified as dorsal 8, is the best preserved
in the series. The neural spine reaches nearly the entire length of
the neural canal. It has a slightly inclined appearance due to the
convex and concave margins of the anterior and posterior mar-
gins of the spine, respectively. Again, the spine appears broken
off above its base. The lateral lamina of the arch is rather short
extending about half the length of the canal. The left transverse
process is present and is the best preserved in the series. The rib
parapophysis lies slightly anterior and medial in the same hori-
zontal plane as the diapophyses but is not immediately anterior to
the diapophysis. This morphology also corresponds to dorsal 8 in
Rhamphorhynchus (Wellnhofer, 1975:fig. 6), assuming nine cer-
vical vertebrae are present instead of eight (sensu Bennett, 2007).
The fossa on the lateral lamina of the neural arch is the most dis-
tinct in the dorsal series and somewhat resembles a pneumatic
foramen, but it does not communicate with an internal space. As
can be seen in the following two vertebrae, which have had their
neural arches sheared off at their lateral laminae, these laminae
curve inward to create the lateral fossae as well as an hourglass
shape for the neural canal in dorsal view. A break in the element
identified as dorsal 10 appears to form a small hole in its right
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ANDRES ET AL.—NEW RHAMPHORHYNCHID PTEROSAUR FROM XINJIANG 175
lateral margin, but this is not a natural hole. Posterior to these
vertebrae, the preservation in the series degrades. The nominal
dorsals 11 and 12 exhibit outlines of their centra, prezygapophy-
ses, left transverse processes, and in the case of dorsal 12, the
right transverse process and left postzygapophysis, but no further
morphological details can be discerned. For the last two dorsal
vertebrae, only the rough outline of centra can be traced. The in-
tervening space before the sacrum also leaves space for only two
dorsal vertebrae.
The dorsal vertebrae in Sericipterus are indistinguishable from
those of other non-pterodactyloids that also have elongate cen-
tra (B. Andres, unpubl. data). Though this specimen lacks the
pneumatic foramina reported in Rhamphorhynchus, pneumatic
features are found in Rhamphorhynchus only anterior to dorsal 5
and are then only visible on the ventral surface of the transverse
processes (Bonde and Christiansen, 2003). Therefore, it cannot
be excluded that this specimen had pneumatic dorsals.
Sacrum and Pelvis—The pelvic region in IVPP V14725 is very
poorly preserved and shifted to the left of the dorsal series (Fig.
2). T he first two sacral vertebrae and one of the ischiopubic plates
can be identified. The total number of sacral vertebrae is un-
known. The sacral vertebrae are fused to one another and to their
sacral ribs. Only the left sacral ribs are present and so the widths
estimated in Table 2 are the result of doubling the distance from
their lateral margins to the midline of the centra. The sacral ribs
are short and flare laterally to enclose a single visible intertrans-
verse foramen. The sacral rib of the first sacral is directed pos-
terolaterally, whereas the following sacral rib is oriented straight
laterally. The anterior cotyle of sacral 1 is visible and is a wide,
dorsoventrally depressed oval. The rest of the sacrum is corre-
spondingly depressed with a flat ventral surface. A thin, broken
neural spine base is visible on the second sacral vertebra. The
broad, fused ischiopubic plate of one half of the pelvis is present.
Its surface texture is quite weathered, but its position suggests
it is the right plate. If correct, then a thickened ridge extending
away from the sacrum would correspond to the main body of the
pubis. All pterosaurs have at least two sacrals, and broad, fused
ischiopubic plates are present in all but the most basal pterosaurs
(Unwin, 2003b).
Pectoral Girdle
In IVPP V14725, the right scapula and coracoid are all that
remains of the pectoral girdle (Fig. 6A, Table 3). These elements
generally fuse with one another during ontogeny (Bennett, 1993),
but in this specimen they are unfused. A 30
◦
degree displace-
ment between the long axes of the scapula and coracoid in the
horizontal plane is most likely an artifact of preservation. The
scapula and coracoid form about a 75
◦
angle with one another
in a sagittal plane. The overall V-shape of these elements is due
to a 90
◦
flexure in the coracoid and a 30
◦
flexure in the scapula
near their contact, as well as a slight 15
◦
curvature along the pos-
terior ramus of the scapula. The glenoid fossa is oriented in the
middle of the lateral surface of the scapulocoracoid. The poste-
rior end of the scapula lacks an articulating facet for the vertebral
column, precluding the possibility that the pectoral girdle had a
laterally rotated anatomical position. The glenoid fossa is saddle-
shaped: concave in the transverse plane and convex in the hori-
zontal plane.
The scapula is almost the same length as the rather elongate
coracoid, but is more curved. Though the posterior ramus is dam-
aged, it can be seen to be dorsoventrally depressed, have a nearly
constant width, and lack an expansion at its posterior end. There
is no distinct supraglenoid or medial buttress. Anterior to the
scapular flexure, however, are medial and lateral tubercles that
are likely the origins of the scapular head of the m. triceps as well
as the confluent m. subscapularis and m. scapulohumeralis poste-
rior, respectively (Bennett, 2003). Anterior to these tubercles, the
TABLE 3. Lengths of the appendicular elements of IVPP V14725 (in
mm).
Element Left Right
Scapula — 71.2
Coracoid — 70.3
Humerus > 80.1 100.2
Ulna > 46.8 > 35.8
Radius > 20.0 > 48.5
First wing phalanx 127.4—
Second wing phalanx — 117.4
Third wing phalanx > 102.7 > 148.3
Fourth wing phalanx > 100.5 117.7
Metatarsal A 91.1
Metatarsal B > 77.9
— = missing element; > = preserved length.
scapula expands to a subtriangular cross-section where it contacts
the coracoid. The scapula constitutes about 60% of the glenoid
fossa, and the dorsal lip of the glenoid fossa on the scapula is
much larger than the ventral lip on the coracoid, extending onto
the posterior margin of the scapula.
The coracoid has a right-angled flexure just ventral to the
glenoid fossa. T he posterior ramus is by contrast very straight
and tapers in depth along its length. It is compressed side to side
anteriorly, becoming dorsoventrally depressed posteriorly. Two
marginal ridges trace this transition in shape down the shaft: one
curving from the dorsal onto the lateral surface and the other
curving from the ventral onto medial surface. These ridges are ru-
gose along part of their lengths and are inferred to be the origins
of the m. costosternocoracoideus and m. supracoracoideus, re-
spectively. These ridges, and concomitant change in shape along
the posterior ramus, give the coracoid shaft a twisted appearance.
The lateral width of the coracoid increases posteriorly and termi-
nates in a medially directed rounded nub, the lateral aspect of
which is damaged. The coracoid likely had an expanded, bifur-
cate sternal articulation, of which the lateral half is missing in this
specimen. The posteroventral lip of the glenoid fossa on the cora-
coid is pierced by a small, oval pneumatic foramen that does not
contact the scapula. Immediately ventromedial to the foramen is
a crescent-shaped rugosity. If this is a muscle attachment site, it
would correspond most closely to the origin of the coracoid head
of the m. triceps. However, Bennett (2003) inferred an origin for
this muscle immediately ventral to the glenoid fossa in Campy-
lognathoides liasicus. An anterior and presumably communicat-
ing pneumatic foramen is present on the anterior margin of the
glenoid fossa ventral lip. The anterior foramen lies in a large dor-
solateral excavation on the base of the acrocoracoid process. The
acrocoracoid process is a sharp process distinct from the continu-
ation of the coracoid shaft but lacks a groove separating the pro-
cess from the glenoid. Though the ventral margin of the process
is damaged, it does seem to have a constricted neck and a subcir-
cular terminal expansion. There is no trace of a biceps tubercle
independent of the acrocoracoid process. At the flexure in the
coracoid, there is a curved rugose ridge that extends along the
anterior quarter of the ventral margin of the lateral surface. This
ridge corresponds to the origin of the m. coracobrachialis as pro-
posed by Bennett (2003).
The scapula in Sericipterus is shorter than most non-
pterodactyloids, which is typically 25% longer than the cora-
coid (Padian and Wild, 2008). Pneumatic features are invari-
ably present in the scapulocoracoid of pterosaurs whenever the
preservation is sufficient to preserve them. In pterodactyloids, the
posterior pneumatic foramen on the scapulocoracoid is a long
opening shared by the scapula and coracoid almost equally. In
non-pterodactyloids, this foramen is much smaller and seems to
be present only on the coracoid (B. Andres, pers. observ.).
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176 JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 30, NO. 1, 2010
Forelimb
Humerus—Both humeri are preserved in IVPP V14725. The
left humerus is missing its dorsal distal condyle and the proxi-
mal end except for part of the base of the deltopectoral crest.
The right humerus is missing its distal ventral condyle and has
a damaged ulnar crest (Fig. 6E–F, Table 3). There are no visi-
ble pneumatic foramina. The humeral head and proximal end of
the humerus are bowed dorsally with respect to the shaft to pro-
duce a corresponding ventral concave surface, typically found in
pterosaurs. The humeral head is positioned on the humerus long
axis in the horizontal plane. The head has a shallow ventral cur-
vature in proximal view with a relative depth about 30% of the
anteroposterior length. The articular surface of the humeral head
is asymmetrically saddle-shaped; though concave in a horizontal
plane and convex in the transverse plane, dorsal and ventral de-
pressions in the middle of the articular surface extend from the
proximal margin posterodistally and anterodistally, respectively.
These depressions give the humeral head the appearance of hav-
ing a constricted middle in proximal view. The posterior margin
of the humeral head extends onto the ventrally oriented ulnar
crest (also termed the medial process or the external, greater, or
posterior tuberosity). Though damaged, the ulnar crest appears
to have the shape of an inflated flange, and is distinct from the
humeral head and shaft. The distal end of the ulnar crest and ad-
joining part of the shaft are missing. The deltopectoral crest is
proximally positioned, but does not reach the proximal margin
of the humerus. It is further separated from the humeral head by
an emargination of its proximal margin, although a small notch
in this emargination is not natural and due to a missing fragment
of bone. In the sagittal plane, the deltopectoral crest extends di-
rectly anteroventrally from the shaft and curves ventrally only at
the anterior-most tip. There is a slight ventral thickening to this
anterior tip. The long axis of the crest is directed anteroproxi-
mally at a 110
◦
angle to the humeral shaft. In dorsal view, the
shape of the deltopectoral crest outlines a tapering base that ex-
tends anteriorly as a rounded, oblong process with a very slight
middle constriction. The base of the deltopectoral crest extends
for about 20% the length of the humerus. Near the distal end of
the crest is a crack along which there has been a slight rotation of
the proximal end, giving the humerus the unnatural appearance
of a posterior ridge. The humerus has a long, nearly straight shaft
that lacks both a middle constriction and a supracondylar process.
The dorsal surface of the shaft bears a pair of anterior and poste-
rior muscle scars that are likely the insertions of the m. latissimus
dorsi and m. teres major, respectively. These are followed dis-
tally by a sinusoidal rugose ridge that possibly corresponds to the
origin of the lateral head of the m. triceps (Bennett, 2003). The
distal ends of both humeri are damaged so that only the dorsal
condyle (also termed the lateral condyle, radial condyle, or ca-
pitulum) is preserved on the right humerus, whereas the ventral
condyle (also termed the medial condyle, ulna condyle, or tuber-
culum) is preserved on the left humerus. Through comparisons
of both humeri, the distal end of the humerus can be inferred to
have had a greatly expanded distal end that is crescent-shaped
in cross-section. The shape of the distal end is due in large part
to the dorsally and ventrally flaring entepicondyle and ectepi-
condyle, respectively. In anterior view, the dorsal condyle is ori-
ented proximoventrally and is flanked by fossae on its proximal
and distal margins. Not much can be seen of the ventral condyle
beyond that it is smaller, and oriented subperpendicular to, the
dorsal condyle.
The humerus of Sericipterus matches closely to that of other
rhamphorhynchids. The shape of deltopectoral crest in this
specimen has been termed ‘tongue-shaped’ in other rham-
phorhynchids (Unwin, 2003a). However, most taxa so described
have a more distinct constriction in the middle of the crest,
whereas this specimen has only a very slight constriction in this
area. This constriction is very pronounced in Rhamphorhynchus
to the point it has been referred to as ‘hatchet-shaped’ and coded
as an apomorphy for this taxon (Kellner, 2003). The deltopectoral
crest of Sericipterus most resembles the relatively less constricted
deltopectoral crest of Scaphognathus.
Antebrachium—The forearm elements of IVPP V14725 are
poorly preserved and little of their morphology can be deter-
mined. They are identified as the proximal ends of the right ulna
and radius, the distal end of the right ulna, and the possible dis-
tal ends of the left ulna and right radius (Fig. 6B–D, Table 3).
The shafts of these elements are straight, subequal in width with
respect to one another, and nearly constant in width along their
preserved lengths. The terminal expansions are less than twice
the widths of the shafts.
The proximal ends of the right ulna and radius are associated
with one another and lay beneath the largest of the isolated teeth
(Fig. 2). They are crushed flat. The proximal end of the ulna is
expanded mostly on its ventral side (Fig. 6C, Table 3). The ole-
cranon process of the ulna (also termed the crest for the inser-
tion of m. triceps brachii; Bennett, 2001a) is a dorsally positioned,
pointed triangular process. The dorsal and ventral cotyles, for ar-
ticulation with the distal condyles of the humerus are recogniz-
able as anterior thickenings on the proximal end, but their exact
margins are obscured by the crushing and slight rotation of the
base of the olecranon process in this region. The middle of the
anterior surface has a short, slightly ventrally curving groove sur-
rounded by a rugose area that is identified as the biceps tubercle.
This is similar to the condition found in Pteranodon but without
a slight elevation. Just distal to this muscle attachment are two
nutrient foramina.
The proximal right radius (Fig. 6B, Table 3) has part of the ven-
tral margin of its shaft damaged, giving this bone an artificially
curved appearance. Fragments of this ventral margin were found
in association with the radius, confirming its original straight ori-
entation. A pointed dorsal process gives the proximal radius a
boot-shaped outline as in other pterosaurs. The cotyle for articu-
lation with the dorsal (radial) condyle of the humerus dominates
the proximal surface of the radius, but it does not extend to the
ventral margin of the proximal end. The articular surface on the
radius only has a single lip due to its sharing the articulation of
the humerus dorsal condyle with the ulna, as in other pterosaurs.
The unique shape of the articular surface of this bone facilitates
its identification as the proximal end of the radius.
A 42.4 mm long, poorly preserved long bone is possibly a distal
section of the left ulna, based on its subequal dorsal and ventral
expansions and cross-sectional shape (Fig. 2). The preservation
of this element is too poor to be certain of this identification thus
its length is not reported in Table 3. The distal end of the left
ulna is better preserved (Fig. 6D, Table 3). The shaft has an oval
cross-section that expands near its distal end. This expansion is
predominantly in the ventral half. A distinct tubercle is present
in the middle of the distal surface of this bone and lies between
two distal concave surfaces. The dorsal and ventral ends of the
posterior surface curve gently anteriorly to give the distal end a
slightly semicircular cross-section. The dorsal surface is expanded
and bears a groove for a flexor tendon along its ventral edge as
well as a thicker dorsal half. A flat area that contacted the distal
end of the radius lies ventral to this groove. The distal end of the
right radius is missing the majority of its articular surface (Fig. 2).
It is identified as the distal end of the right radius on the basis
of its gradual dorsal expansion and a prominence on the ventral
half of the anterior aspect that corresponds to the position of the
anterior tubercle on the distal ends of the radii of other
pterosaurs. The antebrachium in Sericipterus is identical to that
of other non-pterodactyloids so far as preserved.
Manus—The carpus and metacarpus do not appear to be
preserved in IVPP V14725 (see Pes below), but a small cres-
cent shaped bone found adjacent to the distal right radius is
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ANDRES ET AL.—NEW RHAMPHORHYNCHID PTEROSAUR FROM XINJIANG 177
likely sesamoid C of Bennett (2001a). A proximal manual pha-
lanx is the only element representing manual digits I–III. This
phalanx is a short, but narrow, bone with expanded proximal
and distal ends. The distal end is round whereas the proxi-
mal end has an abductor tubercle confluent with its proximal
margin.
Wing Finger—The phalanges of the wing finger (digit IV) in
IVPP V14725 are represented by the left first phalanx, right sec-
ond phalanx, both third phalanges, and both fourth phalanges
(Fig. 6H–M, Table 3). The ratios of their lengths to the first
wing phalanx are 1:0.92:>1.16:0.92. The shafts of the phalanges
are oval in cross-section and are about twice as wide as they are
deep. These cross-sections are ventrally expanded at the ends of
the wing phalanges to form more triangular interphalangeal ar-
ticular surfaces. The proximal and distal ends of these wing pha-
langes are expanded as in most pterosaurs, but they are greatly
expanded in the first two phalanges, the termini reaching at least
twice the width times of their mid-section. The first and second
phalanges are also more symmetrically expanded than those of
the successive phalanges. All of the interphalangeal joints bear
posterior processes with the exception of the proximal end of the
fourth phalanx.
The complete left first wing phalanx is preserved in this
specimen (Fig. 6H). The extensor tendon process is present, but
not fused to the proximal margin of the phalanx. The base of
this process can still be seen in Figure 6H. The extensor tendon
process has the shape of a right-angled triangle in the horizontal
plane, and lacks a notch in its anterior margin. This process
contributes to one third of the ventral cotyle for articulation with
the distal end of the wing metacarpal. The rest of the ventral
cotyle is supported by the ventral half of the proximal margin of
the first phalanx proper. This cotyle terminates posteriorly in a
short, proximodistally extending ridge located in the middle of
the ventral surface of the phalanx. A narrow sulcus separates this
ridge from the posterior half and the proximal posterior process
of the phalanx. The posterior process has a nearly straight
proximal margin, supporting the dorsal cotyle, and terminates
in a rounded tip. The anterior margin of the proximal end of
the first phalanx has a rounded longitudinal flange. When this
phalanx was prepared, a small amount of anterior curvature
was introduced into the shaft, but its original shape was nearly
straight. Distally, this phalanx expands gradually both anteriorly
and posteriorly to terminate in a strongly expanded, convex
distal end. The distal end is almost as wide as the proximal end
and bears a large, blunt posterior process.
The right second phalanx was found in four pieces, with the
distal end lying next to the right third wing phalanx (Fig. 2, 6I). It
is slightly shorter than the first wing phalanx. It also has strongly
expanded ends with a relatively angular posterior process and a
low anterior flange on the proximal end. The distal end has no
anterior expansion, but has a posteriorly curving surface on the
anterior margin of the distal end.
Portions of both third wing phalanges are preserved in this
specimen. The right wing phalanx 3 is missing its proximal end
(Fig. 6J) and the left phalanx is missing its distal end (Fig. 6K).
Though both are incomplete, the third wing phalanx is the longest
of the forelimb elements. The proximal end lacks an anterior
flange but has a distinct posterior process. The left third phalanx
was preserved as five separate pieces and was reconstructed with
a slight sigmoidal curvature to the shaft. This curvature is almost
certainly not natural. The distal end is similar in shape to the dis-
tal end of the second wing phalanx except that the distal end is
only slightly wider than the shaft and bears only a small posterior
process.
Both fourth wing phalanges are preserved in this specimen.
The left phalanx is missing its distal end (Fig. 6L). The proxi-
mal end of the right wing phalanx four is missing its anterior and
posterior margins but can be seen to have a flat proximal end as
in the left wing phalanx four (Fig. 6M). The fourth wing phalanx
is rather elongate and slightly longer than the second wing pha-
lanx. Both left and right elements have a strong posterior flex-
ure in their mid-sections. An anterior flexure in the distal end
of the right phalanx is due to the reconstruction of the element.
As shown by the left wing phalanx four, the proximal end is not
significantly expanded, lacks a posterior process, and has only a
slight anterior flange. The distal end of this phalanx (and thus of
the wing-finger) is a blunt, posteroventrally directed nub. A small
crack is present in this distal tip along which the ventral half has
been shifted slightly to the anterior.
Wing phalanges with an oval cross-section that is twice as wide
as deep have also been reported in the pterodactyloid Dsun-
garipterus (Bennett, 2001a), but not among non-pterodactyloid
pterosaurs. The wing phalanges of Sericipterus differ from other
non-pterodactyloids in having rather large proximal and distal ex-
pansions on phalanges one and two, as well as strong curvature,
and lack of a proximal posterior process on the fourth wing pha-
lanx.
Pes
There are two limb bones in IVPP V14725 that terminate in
a pair of condyles. One is a complete element (Figs. 2, 6N–Q),
whereas the other lacks its proximal end and is more poorly pre-
served (Fig. 2), but otherwise they look the same. These condyles
trace out an approximate 120
◦
arc. Distinct condyles at the end
of a limb bone have not been reported in pterosaurs outside
of the tibia-fibulae and the penultimate manual phalanges, both
of which are too different in size from these elements to be
considered for their identity. In addition, these elements lack
the proximal lateral expansion, cotyles for articulation with the
femur, anteroposteriorly compressed shaft cross-section, large
and terminally positioned condyles, or a fused fibula found in
the tibiae of other pterosaurs. The presence of distal condyles
is indicative of metapodial elements in other taxa. These ele-
ments, however, are relatively larger, longer, and more robust
than both the metacarpals and metatarsals in other pterosaurs.
Three-dimensional metapodial elements are effectively known
only from the two species of Dimorphodon (Padian, 1983; Clark
et al., 1998) in the non-pterodactyloid pterosaurs. When the
metapodial elements in this specimen are compared to other
three-dimensionally preserved metapodials and sufficiently well-
preserved two-dimensional metapodials, they are more similar to
metatarsals and so are identified as such in Figures 2, 6, and Table
3.
The length and size of the metapodial elements in IVPP
V14725 are more indicative of metatarsals, which are longer
than the metacarpals in non-pterodactyloids but not in ptero-
dactyloids (B. Andres, unpubl. data). Either way, this specimen
would have the largest metacarpals or metatarsals of any known
non-pterodactyloid pterosaur. These elements are robust and
laterally compressed, unlike the extremely delicate metacarpals
that are thinner and more rounded in cross-section than the
metatarsals in Dimorphodon (Padian, 1983). These elements are
also perfectly straight whereas metacarpals bow anteriorly (Pa-
dian, 1983). The proximal end of the complete element is lat-
erally compressed and almost symmetrical in outline, unlike the
shallow, U-shaped cross-section of metacarpals (Padian, 1983).
Furthermore, the shape of the proximal end and a slight splay
to the right of the distal end matches the right metatarsal II
of Dimorphodon macronyx (YPM 350). Metacarpals also have
a larger proximal expansion and a smoother distal taper than
the metapodial elements in this specimen that are nearly the
same diameter along their length (B. Andres, pers. observ.). Both
metacarpals and metatarsals have grooves on their distal ends,
but only in metatarsals and the particular metapodials of IVPP
V14725 do they lie in the same plane as the long axis of the
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178 JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 30, NO. 1, 2010
proximal cross-section. A pair of round flanges flanks these
grooves on the ventral aspect of the distal end of the metatarsals
in Dimorphodon, presumably the remnants of the distal condyles.
In the metacarpals, sharp tubercles instead take up this posi-
tion and are more asymmetrically arranged. Though the groove
reaches up onto the distal surface in IVPP V14725, the condyles
maintain a ventral, subterminal position similar to the position
of the pair of flanges in the metatarsals. In Dimorphodon, the
ventral groove terminates at the distal margin to leave a smooth
distal surface that is slightly convex in lateral view (Clark et al.,
1998). In IVPP V14725, this convex distal outline is maintained
but the groove incises up the distal surface to a point three-
quarters up the distal aspect and slightly above the midline of the
shaft. Dimorphodon metacarpals, by contrast, end in terminally
placed rounded bulbs (Padian, 1983), similar to the oval, convex
articular surfaces found in Pteranodon (Bennett, 2001a). These
distal bulbs complement the concave, circular cotyles found on
the proximal surface of the proximal manual phalanges. The
proximal manual phalanx found in this specimen has such a sur-
face and therefore does not mirror the double-condyled metapo-
dials. The metapodial elements listed as metatarsal A and B in
Figures 2, 6, and Table 3 are identified as the right metatarsal
II, and the distal half of another metatarsal of unknown identity,
respectively.
This shape of the articular surfaces of distal metacarpals and
proximal manual phalanges in pterosaurs provide a great free-
dom of movement for the manual digits to engage other animals
or objects (Bennett, 2001b) and to be abducted while splayed lat-
erally should they be used for quadrupedal motion (Mazin et al.,
2003; Unwin, 1997). Identification of the metapodial elements in
IVPP V14725 as metacarpals would preclude these functions in
this individual by restricting the movement at the metacarpal-
phalangeal joint to a single plane. It is most probable that the
metatarsals in IVPP V14725 represent a departure from the typ-
ical morphology of pterosaur metatarsals in that the ventral sul-
cus at the distal end of the element extended up further on to the
distal articular surface to form the distinct condyles. This sulcus
does not reach the dorsal surface of the metatarsal as in pterosaur
outgroups. This individual probably could greatly flex the pedal
digits due to the large ventral condyles. However, the ventral po-
sitioning of the condyles and the termination of the sulcus ventral
to the dorsal surface probably allowed only slight hyperextension
of the pedal digits.
There is also a short bone missing an articular end found near
the right humerus that is tentatively identified as a pedal phalanx.
This bone transitions from a laterally compressed proximal end to
a smaller, subcircular cross-section at the point of its break. The
phalanx is laterally compressed and gently curved along its long
axis. It is identified as a pedal phalanx based on the curvature of
its shaft and its closer size to the identified metatarsals than the
proximal manual phalanx.
PHYLOGENETIC RESULTS
The phylogenetic analysis of Sericipterus wucaiwanensis, gen.
et sp. nov., is the largest and most well-resolved analysis of
basal pterosaur species to date. The analysis produced a single
most parsimonious cladogram (Fig. 7) with a tree length of 145
steps (CI: 0.62, RI: 0.79, RC: 0.49) for all parsimony settings and
tree search methods used. Sericipterus is placed in the Rham-
phorhynchinae (sensu Unwin, 2003a) as the sister group to An-
gustinaripterus longicephalus. This pairing is successively more
closely related to Harpactognathus gentryii, the sister group of
Rhamphorhynchus muensteri and Cacubipteryx caribensis, and
Dorygnathus banthensis within the Rhamphorhynchinae. Re-
moving Sericipterus from the analysis does not alter the rela-
tionships of the remaining taxa. Bootstrap and Bremer support
indices for the clades in the analysis are listed on the clado-
FIGURE 7. Single most-parsimonious cladogram recovered from the
phylogenetic analysis of the relationships of Sericipterus w ucaiw anen-
sis, gen, et sp. nov., and the other non-pterodactyloid pterosaurs.
Bootstrap and Bremer support values for the ingroup nodes are
shown above and below the branches, respectively. Ornithosuchus
longidens, Herrerasaurus ischigualastensis, and Scleromochlus taylori
are used as outgroups. Abbreviations: An, Anurognathidae; Br, Bre-
viquartossa; Ce, Caelidracones; Lo, Lonchognatha; Ma, Macrony-
choptera; No, Novialoidea; Pt, Pterosauria; Rd, Rhamphorhynchidae;
Rn, Rhamphorhynchinae.
gram in Figure 7. The support for most clades within the anal-
ysis is relatively high considering the incompleteness of many
taxa: bootstrap scores are below 50% only for the preferred
sister-group relationship between Jeholopterus ningchengensis
and Dendrorhynchoides curvidentatus, as well as the two basal-
most backbone nodes within the Pterosauria; nodes with Bremer
indices of one are present in the Anurognathidae (sensu Kell-
ner, 2003; Unwin, 2003a) and Rhamphorhynchinae, for the sister
group of Sordes pilosus and Caelidracones (sensu Unwin 2003a,)
as well as for the three basal-most nodes within the Pterosauria.
Sericipterus is firmly placed within the Rhamphorhynchidae
Owen, 1870, requiring at least 16 steps to place it anywhere else
on the cladogram outside of this group. Its sister-group relation-
ship to Angustinaripterus is supported by a single unambiguous
character state change: the gain of an elliptical cross-section of
the rostral process of the skull (character 2, state 1). The skull of
Sericipterus broadly resembles the skull of Angustinaripterus dif-
fering mainly in being larger with more robust skull elements and
otherwise having more extreme versions of the morphology that
distinguish Angustinaripterus from the other non-pterodactyloid
pterosaurs. Two other changes might also support this node: the
ventral orientation of the jugal posterior process (character 19,
state 1) and the lingual curvature of the teeth (character 33, state
1). However, the sister group to this node, Harpactognathus, is
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ANDRES ET AL.—NEW RHAMPHORHYNCHID PTEROSAUR FROM XINJIANG 179
preserved only as a rostrum missing its teeth and so these char-
acters remain ambiguously optimized on the cladogram. Despite
the fact that these three species share only parts of the skull in
their preservation, their grouping is well supported. This clade
of three species has the second highest bootstrap score in the
analysis, and all four characters that support it contribute to its
Bremer score: expansion of the rostrum (character 6, state 1), ap-
pearance of a premaxillary crest (character 7, state 1), undulating
jaw margins (character 30, state 1), and ventrolateral orientation
of teeth (character 37, state 1). Harpactognathus was previously
referred to the Scaphognathinae (Carpenter et al., 2003; Unwin,
2003a). The sister-group relationship of these three species to the
sister group of Rhamphorhynchus and Cacubipteryx also has a
branch length of four steps but with much lower support indices
for this clade. Unlike the two previously mentioned nodes, the
character s tates that support this node are not preserved in each
of the included taxa: all four characters cannot be assessed in
Cacubipteryx and one character in Harpactognathus (character
38) as well as Angustinaripterus and Harpactognathus (character
63). The addition of Dorygnathus to these taxa completes the cir-
cumscription of the Rhamphorhynchinae: Dorygnathus banthen-
sis, Rhamphorhynchus muensteri, their most recent common an-
cestor, and all of its descendents (Unwin, 2003a). This node has
one of the longest subtending branches in the analysis, with eight
steps: advent of subparallel dorsal and ventral margins of the ex-
ternal naris (character 10, state 1); elongate antorbital fenestra
(character 14, state 1); oblique mandible articulation condyles
(character 21, state 1); anterodorsal orientation of the mandible
tip (character 28, state 1); strongly curved teeth (character 32,
state 1); procumbent mesial teeth (character 36, state 1); teeth
not reaching the mandible anterior margin (character 44, state 1);
and pneumatic cervical neural arches (character 45, state 1). The
sister group of the Rhamphorhynchinae, and the only remaining
rhamphorhynchid, is Scaphognathus crassirostris. It is supported
in this position by the dorsal displacement of the external naris
(character 13, state 1) and the elongation of the teeth (character
34, state 1).
The results of the phylogenetic analysis of Sericipterus and
the other non-pterodactyloid pterosaurs are equal parts novel
results and support for previous results. Relationships of these
taxa have been most clearly delimited in the analyses by Kell-
ner (2003) and Unwin (2003a, 2003b). Unwin (1995) provided
the first analysis and Bennett (2007) provides a recent analysis
of non-pterodactyloid pterosaur relationships. Unwin (1995) and
Bennett (2007) are identical to Unwin (2003a, 2003b) except for
the basal-most position of the Anurognathidae in Bennett (2007).
Like Unwin (2003a:fig. 7, 2003b:fig. 2), the current analysis recov-
ers both Preondactylus buffarinii Wild, 1983, as the most basal
pterosaur, and a monophyletic Rhamphorhynchidae. It differs in
that Sordes is sister to the Caelidracones. Because Sordes was
used as a specifier for Unwin’s (2003a) definitions of the Rham-
phorhynchidae and Scaphognathinae, the placement of Sordes
outside of the traditional rhamphorhynchid clade results in both
clades being paraphyletic with respect to the pterodactyloids and
having the same circumscription as each other and the Brevi-
quartossa. The Rhamphorhynchidae in the context of the cur-
rent analysis refers to the traditional grouping; Sordes was origi-
nally referred to the Dimorphodontidae by Sharov (1971). Kell-
ner (2003:fig. 1) placed the different rhamphorhynchids and Sor-
des along the backbone of his cladogram with Rhamphorhynchus
as sister group to the Pterodactyloidea, and Scaphognathus and
Dorygnathus at the third and fourth basal nodes, respectively.
The current analysis recovered a fully resolved Anurognathidae,
matching the results of Kellner (2003) but with the addition of
Jeholopterus as the sister group to Dendrorhynchoides. Unwin
(2003b) recovered an unresolved polytomy for the internal re-
lationships of the Anurognathidae. Despite notable differences,
the current analysis is in agreement with Unwin (2003a, 2003b),
Kellner (2003), and Bennett (2007) for the branching order of Di-
morphodon macronyx, Campylognathoides liasicus, and Rham-
phorhynchus with respect to the Pterodactyloidea.
The current phylogenetic analysis presents a number of novel
results. These results are most discernable in the concordance of
the stratigraphic order with the branching order of the taxa re-
covered in the analysis. Unlike previous work, the current anal-
ysis recovered all of the Triassic pterosaurs at the basal-most
nodes followed by the earliest Jurassic Dimorphodon, the late
Early Jurassic Novialoidea (sensu Kellner, 2003), as well as the
Late Jurassic Sordes and Caelidracones group. Previous results
had later Jurassic taxa interspersed among the Triassic forms and
therefore required the radiation of all major pterosaur groups ex-
cept for the Breviquartossa before the first pterosaur appears in
the fossil record. The most extreme version is the topology from
Kellner (2003), in which three of the at most four basal-most taxa
appear in the Late Jurassic, requiring ghost lineages of at least
50 million years for all three. The concordance with stratigraphy
in the current analysis is realized primarily through the novel re-
sults of a paraphyletic Dimorphodontidae (sensu Unwin, 2003a),
a polyphyletic Campylognathoididae (sensu Unwin, 2003a), and
a sister-group relationship of the Anurognathidae with respect to
the Pterodactyloidea.
Unwin (2003b) and Kellner (2003) address the monophyly
of the Dimorphodontidae (sensu Unwin, 2003a), that is, the
sister-group relationship of Dimorphodon and Peteinosaurus.
Unwin (2003b) placed the two species in a sister-group relation-
ship. Kellner (2003) recovered both in an unresolved trichotomy
with the Novialoidea, and therefore is equivocal with respect to
their relationship to one another. The current analysis did not re-
cover a monophyletic Dimorphodontidae but does place Dimor-
phodon and Peteinosaurus as adjacent terminal taxa along the
backbone of the cladogram, with Dimorphodon closer to ptero-
dactyloids. This is one of two novel results that split a previous
sister group of a Triassic species and a younger species.
The other example is the polyphyly of the Campylognathoidi-
dae. Analyses by Kellner (2003) and Unwin (2003b) both sup-
ported a closer relationship between Eudimorphodon ranz ii and
Campylognathoides than to all other non-pterodactyloids with
the exception of Austriadactylus cristatus, which was placed as
a sister taxon to Eudimorphodon within the Campylognathoidi-
dae by Unwin (2003b). Eudimorphodon and Campylognathoides
share overall skull shapes, similar mandible tips (character 28,
state 2; character 44, state 1), identical deltopectoral crests (char-
acter 54, state 2), similarly-shaped sterna (character 50, state 1), a
second wing phalanx longer than the ulna (character 64, state 1),