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DESCRIPTION OF THE SKULL OF A CTENOCHASMA (PTEROSAURIA) FROM THE LATEST
JURASSIC OF EASTERN FRANCE, WITH A TAXONOMIC REVISION OF EUROPEAN
TITHONIAN PTERODACTYLOIDEA
STEPHANE JOUVE
UMR 5143 du CNRS, Museum National d’Histoire Naturelle, De´partement Histoire de la Terre, 8 rue Buffon,
F-75005 Paris, France, jouvestephane@yahoo.fr
ABSTRACT—A Ctenochasma specimen from the latest Jurassic of eastern France is described in detail and referred to
Ctenochasma sp. The preserved braincase of this specimen has a bird-like lateral position of the optic lobes, with
proportionally a smaller size than in birds, the bones surrounding it being thick and hollow.
An original biometric analysis, based on skull length and tooth number, has been performed using a selection of Late
Jurassic Pterodactyloidea of Europe. This study suggests that Ctenochasma gracile and Ctenochasma porocristata are
senior synonyms of Pterodactylus elegans and Pterodactylus antiquus of Pterodactylus kochi. It also reveals that Ptero-
dactylus elegans may be transferred to Ctenochasma. These results obtained with biometric analyses are confirmed by
morphological observations. This study could not determine if Pterodactylus micronyx is a juvenile of C. roemeri, the
Ctenochasma of Saint Dizier or Gnathosaurus subulatus. Because this species is only composed of juveniles, more data
are needed to determine its adult morphology. The genus Ctenochasma is thus represented by three species, C. elegans,
C. roemeri and C. sp., and Pterodactylus by two, P. antiquus and P. longicollum, all from the Late Jurassic of Germany
and France. This study points out a biological anomaly: all the teeth are not present in a hatching pterosaur, but their
number increase progressively during growth, with new teeth erupting from the front of the jaws. This phenomenon is
particularly spectacular in Ctenochasma elegans, where the tooth number increases progressively from 60 to more than
400 teeth during growth.
INTRODUCTION
In 1972, Taquet published a brief description (Taquet, 1972) of
a new Ctenochasma species (Pterosauria, Pterodactyloidea) from
the Saint-Dizier Museum collections (Haute-Marne, France),
which is described here in more detail. The particular impor-
tance of this specimen is that it preserves parts of its braincase.
Up to now, only a few papers have been devoted to pterosaur
brains. Newton (1889) was the first to describe pterosaur endo-
cranial material in detail, but the specimen he studied was very
fragmentary. Seeley (1901), Edinger (1927, 1929, 1941), Lewy et
al (1992) and especially Kellner (1996) and Bennett (2001) ben-
efited from better material. This paper provides a detailed de-
scription of this Ctenochasma skull, which is shown to belong to
a new species. Moreover, the preserved endocast of this speci-
men permits a restoration of the pterosaur brain. Finally, a bio-
metrical analysis based on skull length and number of teeth for
a sample of Tithonian Pterodactyloidea from Europe permits a
taxonomic revision of this group (Jouve, 2001).
THE CTENOCHASMA OF SAINT DIZIER
Geological Setting—The Mesozoic geological formations in
the vicinity of Saint-Dizier has yielded some vertebrate remains,
including an iguanodontid dinosaur from the Lower Cretaceous
(Lapparent and Stche´pinsky, 1968; Martin and Buffetaut, 1992),
a crocodile (Buffetaut, 1981), and some sauropod vertebrae
(Buffetaut, 1990) from the Lower Tithonian. As far as pterosaurs
are concerned, in addition to the Ctenochasma specimen (Ta-
quet, 1972), only a fragment of ulna was discovered in the Hau-
terivian limestones (Buffetaut and Wellnhofer, 1983). All these
fossils come from well identified stratigraphic levels of Late Ju-
rassic or Early Cretaceous. Unfortunately, the absence of a label
for the pterosaur specimen described here, does not permit cer-
tain identification of its geographic or stratigraphic origins.
According to Vladimir Stche´pinsky, a specialist of the local
geology, this material most probably comes from the “Calcaires
taˆchete´s” (stained limestones), a local Lower Tithonian lime-
stone (Taquet, 1972). The “Calcaires taˆchete´s” are compact
clayey limestones, with very characteristic ferruginous stains
(Me´gnien, 1980a, b). There is almost no doubt that our specimen
comes from this unit, because pink ferruginous stains are abun-
dant in the limestone.
Referred Specimen—75-1671, Muse´e Municipal of Saint-
Dizier (Haute-Marne, eastern France). A skull and the associ-
ated mandible, preserved in two blocks as part and counterpart.
Locality and Age—Most probably from the “Calcaires taˆ-
chete´s”, which outcrop in the vicinity of Saint-Dizier, Early
Tithonian age (Latest Jurassic) (see discussion above).
Morphological Description
Only the skull and mandible of this specimen are preserved
(Figs. 1A, 2A). They are preserved in two slabs as part and
counterpart. The skull is very elongated and low, with a long
muzzle that is concave dorsally. The mandible is broken back to
the symphysis, and its anterior part is almost complete. The skull
length is estimated at about 240 mm. It is laterally crushed, but
the general preservation is rather good, except that some bones
are difficult to identify because they are too crushed or still
embedded in the matrix.
Premaxilla—The anterior part of the premaxilla forms a nar-
row strip. More posteriorly, it extends dorsal to the orbit, before
being obscured by matrix (Pmx, Fig. 1B).
Maxilla—The right maxilla sends a small process in the naso-
antorbital fenestra (Mx, Fig. 1B). This process has been probably
revealed by the compaction, which has shifted up the right pre-
maxilla, which covers normally this process. In the anterior part,
the tooth rows are visible and their anterolateral inclination can
be deduced. The internal face of the maxilla is exposed, revealing
the presence of thecodont alveoli forming little protuberances on
the maxilla in internal view. A part of the anterior palatal blade
of the maxilla is present on the part and counterpart. The max-
illa-jugal suture is not visible.
Journal of Vertebrate Paleontology 24(3):542–554, September 2004
© 2004 by the Society of Vertebrate Paleontology
542
Preorbital Region—It is difficult to determine the initial po-
sition of the bones in this region, as they are distributed on the
part and counterpart and the positions of some bones seem to
have shifted.
On the part (Fig. 1A), the prefrontal (Pf, Fig. 1B) forms a
process in the nasoantorbital fenestra. This process was probably
covered by the premaxilla, which has been moved up during
diagenesis. The prefrontal is progressively rounded and postero-
laterally fractured, exhibiting a cavity which seems to continue
below the orbit (Fig. 3A).
Below the prefrontal, the nasal points forward in the nasoant-
orbital fenestra (N, Fig. 3). It is broken in its posterior part, and
as for the prefrontal, the cavity that it contains seems to continue
posteriorly over the orbit. The anterior part of this cavity forms
a large gap (?Obc, Fig. 3) in the nasal (this cavity does not appear
to possess a lateral wall). This part may have been covered by the
hollowed and laterally projecting lacrymal (lateral part on the
second block, L, Fig. 2A). The contact with the jugal is not clear
(J, Fig. 3B), and the bone seems to have been forced into the
skull during diagenesis.
These cavities might be principally pneumatic, serving to
lighten the skull. Some may have communicated with the naso-
antorbital fenestra, where a large wide pneumatic cavity should
have existed (Kellner, 1996; Witmer, 1997) as in Tapejara welln-
hoferi (Kellner, 1996).
It is possible that the large nasal gap (?Obc, Fig. 3B) described
above may have contained the olfactory bulbs, situated anterior
to the orbits as in alligators (Romer, 1956). This could imply that
the olfactory bulbs could have a morphology closer to non-
dinosaurian archosaurs (e.g., Alligator, Fig. 4C) than to the de-
rived condition in birds (e.g., Columba livia, Fig. 4D), in contrast
to the hypothesis that the olfactory bulbs were located behind
the orbits, as in birds (Edinger, 1941:fig. 4B; Colbert, 1946:fig.
4C; Hopson, 1979:fig. 4E, F).
Jugal—The right jugal is exposed on its internal face and is
very crushed. The internal bony lamina is missing, exposing the
internal surface of the external lamina (Fig. 2A, and J, Fig. 2B).
The posterior process of the jugal extends as far as the middle of
the nasoantorbital fenestra and does not participate in the lower
temporal fenestra. The anterior ascending process is in poor con-
dition and only its distal portion, with the lacrymal-jugal suture,
is present. The limit of the anteroventral process with the maxilla
cannot be seen.
Quadratojugal—The quadratojugal is very damaged and is
exposed in internal view (Qj, Fig. 2B). It develops a thin anterior
process below the jugal and seems to form a thin and sharp
FIGURE 1. Skull and mandible of Ctenochasma sp. (Muse´e Municipal of St Dizier, 75-1671) in lateral view (A and B). Abbreviations:Ec,
endocranial cavity; F, frontal; Hb, hollow space between the outer and inner walls of the braincase; Iw, inner wall of the braincase; J, jugal; L,
lacrymal; Md, mandible; Mx, maxilla; Mxp, maxillary process; N, nasal; Nf, nasoantorbital fenestra; O, orbit; Op, opisthotic; Ow, outer wall of the
braincase; Pf, prefrontal; Pmx, premaxilla; Ptf, posttemporal fenestra; Q, quadrate; Rap, retroarticular process; Sq, squamosal; Sr, sclerotic ring; To,
tooth.
JOUVE—ACTENOCHASMA SKULL FROM FRANCE 543
process bordering the anterodorsal margin of the lower temporal
fenestra to contact the postorbital. The contacts with the other
bones are very difficult to determine.
Postorbital—The postorbital is situated very low at the pos-
terior part of the orbit (Po, Fig. 2B), and its contact with the
quadratojugal suture can be seen in its internal face, as is the case
with the jugal. The ascending process enters into the matrix, and
the complete contact with the frontal is visible. A small foramen
is present at the base of the ascending process.
Quadrate—The quadrate is long, thin, and its proximal part is
covered by the squamosal, whereas the distal part is preserved in
articulation with the mandible (Q, Fig. 1B). The quadrate has a
sharp anteroventral inclination, such that its long axis is nearly
parallel to the plane of the palate.
Squamosal—The squamosal is badly damaged, and seems to
be very rounded, such that it is not ventrally continuous with the
quadrate and the parietal (Sq, Figs. 1B, 2B).
Sclerotic Ring—About half of the sclerotic ring is present in
situ within the orbit (Sr, Fig. 1B). Only six plates are preserved,
each one being exhibiting a concavity for the next plate.
Postorbital and Encephalic Region—The braincase is broken
longitudinally at about the mediolateral midpoint of the right
parietal and frontal, exposing the endocranium (Figs. 5A, 6A).
The preserved part of the frontal (F, Fig. 5B) suggests that it may
have formed a lateral triangular point on the counterpart (F, Fig.
6B), in which there is a little concave bony plate about 1 cm
2
(Iw,
Fig. 6B), corresponding to a more or less continuous thin oval
bony wall on the part (Iw, Fig. 5B). Along with the blade on the
part, this oval bony wall seems to delimit the lateral wall of the
endocranial cavity (Iw, Fig. 6B) which appears to have been an
oval bony sphere. Moreover, some vascular impressions, corre-
sponding to the meningeal vessels are visible on the endocranial
cavity wall (Vp, Fig. 6B). The endocranial cavity is small, and
deep inside the braincase, and the bones forming the braincase
were thick and hollow.
The bony blade (Iw, Fig. 6B) is marked by a bulge in its lower
part, dividing it into two concavities. This bulge probably marks
the limit between the telencephalon and the mesencephalon (Te
and Ms, Fig. 4G). This respective positions of the telencephalon
and mesencephalon, one above the other, establishes a parallel
FIGURE 2. Skull and mandible of Ctenochasma sp. (Muse´e Municipal of St Dizier, 75-1671) in lateral view (A and B). Abbreviations:F, frontal;
Hb, hollow space between the outer and inner walls of the braincase; Iw, inner wall of the braincase; J, jugal; L, lacrymal; Ltf, lower temporal fenestra;
Md, mandible; Mx, maxilla; O, orbit; Ow, outer wall of the braincase; Po, postorbital; Qj, quadratojugal; Rap, retroarticular process; Sq, squamosal;
Utf, upper temporal fenestra.
JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 24, NO. 3, 2004544
between the Ctenochasma brain and those of birds, and the well
developed mesencephalon (Figs. 4D, G), suggests significant vi-
sual acuity.
Occipital Region—On the part (Figs. 1A, 5A), an opening
under the endocast could be the posttemporal fenestra (Ptf, Figs.
1B, 5B), as defined by the squamosal and the opistothic (Op,
Figs. 1B, 5B). The occipital region appears very concave an-
terodorsally.
Mandible—The mandible is relatively complete; only the most
anterior teeth are missing. The mandible is broken just posterior
to the symphysis, and its right ramus is still articulated with the
quadrate. The anterior part is broken longitudinally on the two
blocks (Md, Figs. 1B, 2B), exposing the teeth in their alveoli. The
posterior part of the mandible is very damaged, and it is not
possible to differentiate the dentary from the other mandibular
bones. Anteriorly, the dentary bears a very long symphysis in-
cluding 37 teeth. The retroarticular process is elongated and
rounded posteriorly in lateral view (Rap, Figs. 1B, 2B).
Dentition—As described above for the Maxilla, each tooth is
located in a single alveolus (To, Fig. 1B). Only four pulp cavities
are exposed, but other teeth show mineralized concretions at
their bases, which can be identified either as replacement teeth
or simply as a fossilization artifact.
The teeth are long (14 mm for the longest), thin (less than 1
mm width), slightly flattened anteroposteriorly, and the whole
tooth row forms a basket with the anterior teeth being the long-
est. The number of teeth is estimated to be 45–50 on each jaw
row, so that the total number is about 200 teeth.
Comparisons
The presence of an external naris displaced posteriorly relative
to the premaxillary tooth and the absence of a quadratojugal-
squamosal contact, are synapomorphies of the Pterosauria Kaup,
1834 (Bennett, 1996a). The confluence of the nasal and antor-
bital fenestra is a synapomorphy of the Pterodactyloidea (Welln-
hofer, 1970). The elongated beak, the lateral direction of the
teeth on the jaws, the thin dentition, and the high tooth count are
all synapomorphies features of Ctenochasmatidae (Wellnhofer,
1970).
Some studies of pterosaur brains (e.g., Meyer [1860], which
described a Pterodactylus kochi endocast), suggested that they
FIGURE 3. Ctenochasma sp. (Muse´e Municipal of St Dizier, 75-1671), detail of the preorbital region. Abbreviations:J, jugal; N, nasal; Nf,
nasoantorbital fenestra; O, orbit; ?Obc, presumed olfactory bulb cavity; Ca, pneumatic cavity; Pf, prefrontal; Pmx, premaxilla.
FIGURE 4. Comparison of different brains: A,‘Pterodactylus kochi’;B,‘Pterodactylus elegans’;C,Alligator;D,Columba livia;E,F,Parapsi-
cephalus purdori (lateral and dorsal view); G,Ctenochasma sp. Abbreviations:C, cerebelum; Ms, mesencephalon; O, orbit; ?Ob, presumed position
of the olfactory bulb; ?On, presumed position of the olfactory nerve; Te, telencephalon. (A, B and D after Edinger, 1941; C, modified from Romer,
1970; E and F after Hopson, 1979).
JOUVE—ACTENOCHASMA SKULL FROM FRANCE 545
had large brains relative to skull size, occupying the entire brain-
case (Fig. 4A). ‘Endocranial cavity’is here used to designate the
cavity which contains the brain (Ec, Fig. 5B), and ‘braincase’is
used to designate the cavity that contains the endocranial cavity
and the hollow space between the outer and inner wall of the
braincase. Similar observations have been made on Pterodac-
tylus elegans (Edinger, 1941; Fig. 4B), Rhamphorhynchus
(Edinger, 1927) and a pterodacyloid from the Cambridge Green-
sand (Edinger, 1927, incorrectly referred to ?Pteranodon [Ben-
nett, 2001]). Other significant discoveries are the endocasts of
Parapsicephalus purdoni (Newton, 1889; Hopson, 1979; Figs. 4E,
F), and of another unknown species (Lewy et al., 1992).
Thanks to acid preparation, it has been established recently
that in Tapejara wellnhoferi the brain did not occupy the totality
of this braincase (Kellner, 1996). Indeed, the bones surrounding
the endocranial cavity show an important bony trabecular system
in a pneumatic cavity, which, in Tapejara, probably originated
from frontals, supraoccipitals and parietals (Kellner, 1996), with
the brain occupying only about one-third of the total volume of
the braincase. In Pteranodon, the bones surrounding the endo-
cranial cavity are pneumatic and show a cavity spanned by bony
struts as in Tapejara, but delimited by an inner wall (Bennett,
2001). The same structures are observed in Ctenochasma, with a
large hollow space between the outer and inner walls of the
braincase. The trabecular system formed by thin pillars, although
not preserved here, but was probably present in the large cavity,
as in Tapejara and Pteranodon. Furthermore, some very dam-
aged thin bony blades (T, Fig. 5B) are visible and could belong
to the system of trabeculae. Because Tapejara,Pteranodon and
Ctenochasma are not closely allied phylogenetically (Unwin,
1995; Unwin and Lu¨, 1997; Jouve, 2000), it seems unlikely that
the pneumaticity of the bones surrounding the endocranial cavity
and placing the brain deep in the skull is a homoplasy. It is more
plausibly a synapomorphy of Pterosauria, or at least one defining
Pterodactyloidea, in which the brain occupies a little part of the
endocast. The absence of the inner wall of the braincase in Tape-
jara, appears to be a derived feature of this taxon absent in
Ctenochasma and Pteranodon.
The assertion by Edinger (1941) that the “Pterodactylus el-
egans”endocast is the same size than the braincase (Edinger,
1941), could be due to a misinterpretation, or possibly to positive
allometric growth of the skull relative to the brain, in which case
the brain of the adult (Ctenochasma, see below) as suggested
Bennett (pers. comm.), would occupy a relatively smaller frac-
tion of the skull volume than it would in the juvenile. The three
dimensional pterosaur braincases described by Edinger (1941),
Hopson (1979), and Lewy et al. (1992) do not seem to reflect the
natural brain shape, but instead the very pneumatic condition of
the braincase, at least in adult specimens. Thus, the restorations
of pterosaur brains comparable in size to those of birds, and the
size/weight assessment of the brain used in some works (Hopson,
1977; Langston, 1981; Jerison, 1973) should be reviewed (Fig.
4G, with attempted restoration of the brain of Ctenochasma).
The position and shape of the olfactory bulbs in Ctenochasma
is highly atypical. They seem long and situated anterodorsally to
FIGURE 5. Ctenochasma sp. (Muse´e Municipal of St Dizier, 75-1671),
detail of the encephalic region, part. Abbreviations:Ec, endocranial
cavity; F, frontal; Hb, hollow between the inner and the outer wall of the
braincase; Iw, inner wall of the braincase; Op, opisthitic; Ow, outer wall
of the braincase; Ptf, posttemporal fenestra; T, trabeculae.
FIGURE 6. Ctenochasma sp. (Muse´e Municipal of St Dizier, 75-1671),
detail of the encephalic region, counterpart. Abbreviations:F, frontal;
Hb, hollow between the inner and outer walls of the braincase; Iw, inner
wall of the braincase; Ow, outer wall of the braincase; Vp, vascular prints.
JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 24, NO. 3, 2004546
the orbits in this Ctenochasma, whereas they have previously
been described as very small, short, and located posterodorsally
to the orbits in other pterosaurs (Edinger, 1927, 1941). In other
archosaurs, such as the crocodylomorphs Sphenosuchus (Walker,
1990), Sebecus (Colbert, 1946), Pholidosaurus meyeri (Edinger,
1929), and Goniopholis (Edinger, 1938), and the theropod dino-
saurs Stenonychosaurus (Russell, 1969; Currie, 1985), Allosaurus
(Rogers, 1999) and Tyrannosaurus (Brochu, 2000, 2003), the po-
sition of the olfactory bulbs is far anterior to the telencephalon,
and anterodorsal to the orbits. The only exception to this trend
known within archosaurs is the short olfactory bulbs of birds. If
the observation made here is valid, the condition of the olfactory
bulbs in pterosaurs is closer to the primitive condition observed
in archosaurs than to the derived state seen in birds.
The Ctenochasmatidae includes two genera, which are mainly
differentiated by the number and shape of their teeth (Wellnhofer,
1970, 1978): Ctenochasma Meyer, 1852, has thin and numerous
teeth (200 to 360), that are equal in size anteriorly, becoming gradu-
ally shorter posteriorly, whereas Gnathosaurus Meyer, 1834, bears
128–136 long, but more robust teeth, the size of which decrease
quickly in the caudal 80% of the length of the tooth row.
On the basis of its thin and very numerous teeth (more than
200), and the progressive decrease of the tooth size posteriorly,
the Saint-Dizier specimen can be referred to Ctenochasma. Three
species of Ctenochasma have been described: (1) C. roemeri Meyer,
1852, known only by the anterior part of a single lower jaw, has
200 closely set and relatively robust teeth (Meyer, 1852; Broili,
1924); (2) C. porocristata Buisonje´, 1981, known from the ante-
rior part of the skull, has 408 very thin teeth; (3) C. gracile Oppel,
1862, the best documented species represented by several speci-
mens has 360 thin teeth (for the largest specimen) close to Cteno-
chasma porocristata ones (Buisonje´, 1981; Broili, 1924, 1936).
The Saint-Dizier Ctenochasma has a skull one-third smaller
than Ctenochasma roemeri, but has the same tooth count, and
similar dental morphology (Appendix 1), with differences in size
(about 20 mm for C. roemeri and 14 mm in C. sp.) and space
between the teeth (1.5 to 2 mm in C. roemeri,and1mminC.
sp.). On the other hand, its tooth count is smaller than that of the
biggest specimen of Ctenochasma gracile, despite its larger skull
size. The Saint-Dizier specimen has the same skull size as Cteno-
chasma porocristata, but half as many teeth (Appendix 1). Fur-
thermore, the teeth of Ctenochasma sp. are more robust than
those of C. gracile or C.porocristata, and its upper tooth row
extends far behind the anterior margin of the nasoantorbital
fenestra (Fig. 1), whereas in C. porocristata and C.gracile, the
more posterior teeth stop at the level of or anterior to the ante-
rior margin of this fenestra (1920 I 57, Broili, 1924; 1935 I 24,
Wellnhofer, 1970). On the lower jaw, the tooth row extends far
behind the level of the mandibular symphysis in the Saint Dizier
specimen, whereas there is a large distance between the last
posterior teeth and the symphysis (small specimen, Wellnhofer,
1970:pl. 11, Fig. 3) or the tooth row stops at the level of the
symphysis in C. gracile (large specimen, 1920 I 57, Broili, 1924).
The specimen described here cannot be referred to the three
extant species. Nevertheless, it can be noted that both the largest
specimens of C. gracile and C. porocristata share some similari-
ties (thickness and size of teeth), indicating that the second spe-
cies could be considered as an adult of the first. The same prob-
lem applies to all European Tithonian Pterodactyloidea, espe-
cially for the genus Pterodactylus, for which some species of
smaller size occur in nearby deposits (Mateer, 1975; Bennett,
1992, 1993, 1996b, 2002).
TAXONOMIC REVISION
Several works have mentioned the problem of ‘small’species
in pterosaurs (Mateer, 1975; Bennett, 1992, 1993, 1996b, 2002),
especially noteworthy for the genus Pterodactylus, which in-
cludes mostly small-size species. Indeed, ‘small’species are often
represented by juvenile specimens, whereas juvenile specimens
are generally not represented in similar in larger species. This
implies that the ‘small’species could represent juvenile speci-
mens of the largest ones (subadult or adult specimens).
Wellnhofer (1970) identified young Pterodactyloidea from the
Solnhofen limestone by comparing the degree of ossification of
the tarsus, which is incompletely ossified in juveniles, and the
S.O.L. indices (Scha¨del-Orbital-La¨ngen-Index ⳱Orbit diameter
×100/skull length). The relative orbit diameter increases less
rapidly than the skull length during the first stages of growth
(allometric growth) so that the S.O.L. of juveniles and adult are
very different. In adults or subadults, the orbit diameter and the
skull length increase proportionally so that the S.O.L. indices
stabilize. This allometric growth could be observed in several
living vertebrate species, where the muzzle is proportionally
short in juveniles and gets longer during growth (Kalin, 1933;
Wellnhofer, 1970; Jouve et al., 2001). This method, tested with
crocodilians (Kalin, 1933) permits differentiation of juveniles
from subadults and adults (Jouve, 2000).
More recently, some works using statistical analysis (Mateer,
1975; Bennett, 1996b) have tested ‘large’species and ‘small’spe-
cies from the same locality (Solnhofen), were adults and juveniles
from the same species. Mateer (1975), who performed a morpho-
metric multivariate analysis, concluded that Pterodactylus kochi
could be a juvenile of Pterodactylus antiquus. Bennett (1996b)
performed a statistical analysis using different measurements,
and examined specimens to determine their ontogenic age using
size-independent characters. He suggested the following groups:
Pterodactylus elegans and Ctenochasma gracile could be juveniles
of the same species, Pterodactylus kochi and P. antiquus could be
immature specimens, the adults of which might be found in P.
longicollum or Germanodactylus,andPterodactylus micronyx
could be a juvenile of Gnathosaurus subulatus. Moreover, his
analysis of skeletal elements reveals that Pterodactylus kochi,P.
elegans and P. micronyx have markedly different proportions,
which could imply that they belong to different species, and that
P. antiquus does not differ significantly from P. kochi.
A new method is proposed here to discriminate these species.
Morphological features are used to confirm the results. A selec-
tion of Late Jurassic European Pterodactyloidea (Appendix 1)
were used for this study. In order to compare the Saint-Dizier
Ctenochasma to other taxa, the selection has been made using
taxa where the skull and teeth were available.
In some reptiles the tooth count increases during ontogeny, as
in elasmosaurids (Gasparini et al., 2003) and probably also in
thalattosuchians (Vignaud, 1995). The method consists thus of a
comparison between the skull length and the number of teeth, to
determine if the different species represent different growth
stages of the same species (Fig. 7). The total number of teeth is
calculated as the teeth present on a half upper jaw plus a half
lower jaw, and when only lower or upper jaw is known, this
number is multiplied per two.
On the graph obtained (Fig. 7), different species are lined up
and will be discussed below: (1) Pterodactylus elegans,Cteno-
chasma gracile and C. porocristata; (2) Pterodactylus kochi,P.
antiquus and Pterodactylus sp.; and (3) Pterodactylus micronyx,
Ctenochasma sp., C. roemeri or Gnathosaurus subulatus.
SYSTEMATIC PALAEONTOLOGY
PTEROSAURIA Kaup, 1834
PTERODACTYLOIDEA Plieninger, 1901
CTENOCHASMATIDAE Nopcsa, 1928
CTENOCHASMA Meyer, 1852
CTENOCHASMA ELEGANS (Wagner, 1861)
Holotype—Solnhofen, Malm, 1875 XIV 501, Bayerische
Staatssammlung fu¨r Pala¨ontologie und historische Geologie,
JOUVE—ACTENOCHASMA SKULL FROM FRANCE 547
Mu¨nchen; named: Pterodactylus elegans, (Zittel, 1882). A juve-
nile specimen.
Synonymy—Pterodactylus elegans Wagner, 1861; Cteno-
chasma gracile Oppel, 1862; Non Pterodactylus elegans Wagner
(Rikovsky, 1925); Non Pterodactylus elegans Wagner (Broili,
1925); Non Pterodactylus elegans Wagner (Edinger, 1941); Ptero-
dactylus sp. (Mayr, 1964); Ctenochasma porocristata Buisonje´, 1981.
Emended diagnosis—Pterodactyloidea with numerous (more
than 400 in adult), closely-spaced, very long and extremely slen-
der teeth, which are laterally directed, forming a basket. The
more posterior teeth reach the level of the anterior margin of the
nasoantorbital fenestra. Very slender and extremely elongated
snout, nasoantorbital fenestra short; mandibular tooth row ends
at the level of the symphysis; moderate length neck, short meta-
carpal IV, long wing phalanx 1, short femur.
Discussion—On the graph (Fig. 8), Pterodactylus elegans,
Ctenochasma gracile, and C. porocristata are lined up, suggesting
that they could represent one species with different growth
stages. It should be noted that Bennett (1996b) obtained the
same results using a different method, especially that Pterodac-
tylus elegans is a juvenile of Ctenochasma gracile. The present
work permits us to link C. porocristata to these two species.
The skull of Pterodactylus elegans exhibits juvenile characters
such as large orbits compared to the skull length, a nasoantor-
bital fenestra much smaller than the orbit, and very thin teeth,
which are restricted to the anterior part of the jaws. In C. gracile
the snout is more elongated, the nasoantorbital fenestra larger,
and the tooth row more extended posteriorly. In C. porocristata,
the teeth extend much farther posteriorly, reaching the anterior
level of the nasoantorbital fenestra. When Buisonje´(1981) de-
scribed C. porocristata, the possibility than it was an adult of C.
gracile was first considered but later rejected with the arguments
that C. porocristata possesses more teeth, a larger skull, a rela-
tively longer maxillary toothed area, a broader beak and, of
particular importance, a premaxillary crest. Buisonje´regarded
the premaxillary crest as an important taxonomic character, fol-
lowing Wiman (1925) who separated Germanodactylus cristatus
and Pterodactylus kochi into two species on the basis of this
feature. Other morphological characters permit separation of
these last two species. The first characters (teeth number, skull
length, maxillary teeth area and beak development) increase
progressively during ontogeny (Edmund, 1969; see below). The
premaxillary crest is probably a character that appears late dur-
ing ontogeny or, as suggested by Bennett (1992), a sexual char-
acter. In crocodilians, the teeth appear from front to back during
embryogenesis, and all the total number of tooth of adult is
present in the hatching animal (Edmund, 1960, 1962, 1969). In
Ctenochasma, the teeth probably appear from the front to the
back of the jaws during embryogenesis, as in crocodilians, but
due to the high tooth count, the phenomenon continues for a
long time after the hatching. This explains the posterior elonga-
tion of the tooth row during its growth, represented by the three
stages P. elegans,C. gracile and C. porocristata.
Morphologically, some characters permit the grouping of P.el-
egans,C. gracile and C. porocristata and their differentiation
from the other pterodactyloids, permitting synonymy of these
three species within Ctenochasma elegans. The characters de-
scribed below are mainly cranial characters, the postcranial ones
used in the emended diagnosis come from Bennett (1996b).
The snout is more elongated in these three ‘species’than in the
other pterodactyloids, as shown in the SOL/skull length graph
(Wellnhofer, 1970:fig. 17, p 90), where the values for P. elegans
FIGURE 7. Diagram comparing the skull length with number of teeth for different species of Pterodactyloidea. Continuous line shows the
regression for C. gracile (R
2
⳱0.9878), long discontinuous line for P. micronyx (R
2
⳱0.7379), and short discontinuous line for P. kochi (R
2
⳱
0.2595).
JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 24, NO. 3, 2004548
are separate from those of the other taxa. The same thing is
observed for C. gracile, whose the SOL value (specimen 1935 I
24, SOL ⳱8; pers. obs.) is lower than in P. antiquus (specimen
AS I 739, SOL ⳱14.3; Wellnhofer, 1970) and P. kochi (specimen
1883 XVI 1, SOL ⳱15; Wellnhofer, 1970) for about the same
skull length (about 110 mm) (Jouve, 2000). The snout is ex-
tremely elongated (particularly in adult forms), the nasoantor-
bital fenestra is proportionally shorter than in other pterodacy-
loids. The shape of the teeth and their arrangement on the jaws
had particular importance since, when compared to the condi-
tion in other Pterodactyloidea, the teeth are longer, more slen-
der, more closely-spaced and laterally directed, forming a basket
for trapping prey. The dorsal margin of the skull is concave in P.
elegans,C. gracile and C. porocristata,asinP. micronyx (which
is probably a juvenile of Ctenochasma, see below), but contrary
to the conditions in P. antiquus and P. kochi.InP. elegans, the
anterior teeth are short, increasing in size progressively to reach
their maximal length at the half of the tooth row, and decreasing
progressively posteriorly. This tooth organisation is observed in
Ctenochasma, in contrast to the homodont teeth of P. kochi,P.
antiquus,P. longicollum and Germanodactylus.
The teeth of the other Ctenochasma species are much more
numerous, thinner and closer than those of the Saint Dizier
Ctenochasma or in C. roemeri, and the length of the tooth row is
smaller in C. gracile or C. porocristata than in the Saint Dizier
specimen (see above).
Therefore, these three species, P. elegans,C. gracile and C.
porocristata represent three different growth stages of a single
species, for which the specific name C. elegans has priority over
C. gracile or C. porocristata, leading the new combination: Cteno-
chasma elegans.
PTERODACTYLIDAE Bonaparte, 1838
PTERODACTYLUS Cuvier, 1809
PTERODACTYLUS ANTIQUUS (Soemmerring, 1812)
Holotype—Solnhofen, Malm, ASI 739, Bayerische Staats-
sammlung fu¨r Pala¨ontologie und historische Geologie, Mu¨nchen;
original description: Collini 1784; named: Ornithocephalus anti-
quus, (Soemmering, 1812). Immature specimen (Bennett, 1993).
Synonymy—Reptile volant (Cuvier, 1801); Pterodactyle Cu-
vier, 1809; Ornithocephalus antiquus Soemmerring, 1812; Ptero-
dactylus longirostris Cuvier, 1819; Pterodactylus kochi Wagner,
1837; Ornithocephalus kochii (Wagner, 1837); Pterodactylus
meyeri Meyer, 1842; Pterodactylus scolopaciceps Meyer, 1850;
Non Pterodactylus longirostris Meyer, 1859:Tab.1, Fig. 1; Ptero-
dactylus spectabilis Meyer, 1861; Pterodactylus elegans Wagner.
(Zittel, 1882); Non Pterodactylus kochi Wagler (Plieninger,
1901); Non Pterodactylus antiquus (Soemmering, 1812) (Abel,
1925); Pterodactylus cormoranus Do¨derlein 1929; Non Pterodac-
tylus antiquus Soemmering 1818 (Huene, 1951); Non Germano-
dactylus kochi (Wagler) (Young, 1964); Pterodactylus Ho¨lder
and Steinhorst, 1964; Non Diopecephalus kochi (Wagler) (Kuhn,
1967); Pterodactylus sp. Frey and Tischlinger, 2000.
Diagnosis—Pterodactyloidea with an elongated skull whose
the dorsal margin is straight; slender and elongated snout; fenes-
tra nasoantorbital length about twice that of the orbit; approxi-
mately 90 conical and robust teeth; upper tooth row reaches or
extends posterior to the level of the anterior margin of the na-
soantorbital fenestra; nasal process very slender and perpendicu-
lar to the maxilla.
Discussion—Pterodactylus kochi,Pterodactylus antiquus and
Pterodactylus sp. are lined up on the graph (Fig. 8), which could
FIGURE 8. Diagram comparing the skull length with the teeth number of different species. The continuous regression line represents P. elegans
+C. gracile +C. porocristata (R
2
⳱0.9872); the discontinuous line shows P. kochi +P. antiquus +P.sp(R
2
⳱0.5692).
JOUVE—ACTENOCHASMA SKULL FROM FRANCE 549
indicate that they correspond to the same species. Mateer (1975)
and Bennett (1996b), using different analyses, suggested the
same result for P. kochi and P. antiquus. The only noteworthy
morphological differences noted by Wellnhofer (1970) between
these two species, are the tooth size and the number of teeth
(Bennett, 1996b). The characters used by Wellnhofer (1970),
skull length, neck length, and the size of the nasoantorbital fe-
nestra, vary during growth. As seen above, the tooth number
varies during growth in Ctenochasma, and the same phenom-
enon is observed in P. antiquus and P. kochi (Fig. 8), making the
tooth count an invalid taxonomic character. As the Solnhofen
pterosaur specimens are often very crushed and compressed, the
apparent size of the teeth can be modified. Moreover, this im-
portance and extent of dental size variation is not clear (Bennett,
1996b).
Morphologically, P. antiquus and P. kochi have several com-
mon characters. Their skulls are elongated, the nasoantorbital
fenestrae are very long (for the largest specimens of P. kochi),
the dorsal margin of the skull is straight (which is not the case in
Pterodactylus longicollum), and a prominent nasal process pen-
etrates the nasoantorbital fenestra almost vertically. The tooth
row is composed of robust and conical teeth and reach or extends
posterior to the level of the anterior margin of the nasoantorbital
fenestra.
Therefore, these two species, P. antiquus and P. kochi repre-
sent two different growth stages of a single species, for which the
specific name P. antiquus has priority over P. kochi. All the
characters given in the diagnosis are from the largest specimens
(subadult).
Frey and Tischlinger (2000), described a new specimen of
Pterodactylus (named Pterodactylus sp.), and compared it with
Pterodactylus antiquus. The authors noted the similarities with
this species, but did not assign it to P. antiquus because it lacks
a dentary crest. As far as the ventral dentary crest is concerned,
it could be a fossilization artifact due to compaction leading to
spreading of the bone at the thicker symphysis level, besides the
same phenomenon can be observed on a specimen of Pterodac-
tylus ‘kochi’ (Fig. 9). The morphology of P. sp. is close to that of
P. antiquus, with very robust teeth type very closely spaced, the
same orbit shape, nasoantorbital fenestra low and relatively long,
a skull that is long, low and dorsally straight and a dorsoventrally
narrow and straight lower jaw. The Frey and Tischlinger’s specimen
is grouped with the P. antiquus specimens in the graph (Fig. 8),
and it is highly probable this specimen is a member of this species.
Bennett (1996b) grouped together Pterodactylus antiquus,P.
kochi,P. longicollum, and the two species of Germanodactylus,
suggesting that they might actually represent two biological spe-
cies. He changed his mind later (Bennett, 2002), indicating that
Germanodactylus was a valid genus.
In the graph (Fig. 8), P. longicollum is not far from the largest
specimens of P. antiquus, and the difference is not statistically
significant. Biologically, there are great differences. All P. lon-
gicollum specimens have the same tooth count (about 30), when
the skull size increases (from 147 to 215 mm), showing that the
adult number of teeth has been reached in this species. In P.
antiquus and P. kochi, the variation of the tooth number is larger,
with 10 to 15 teeth more (40 to 45) than in P. longicollum, despite
the shorter skull lengths (100 to 140 mm). Moreover the largest
specimens of P. antiquus are immature, whereas the P. longicol-
lum ones are adult (Bennett, 1996b). The number of teeth in
adult specimens of P. longicollum is about 30, and in P. antiquus,
the count is probably at least 45. The same arguments can be
made for the two species of Germanodactylus, which have the
same tooth number as P. longicollum, and are all adult speci-
mens.
Morphologically, there are many important differences be-
tween P. antiquus and P. longicollum. The dorsal margin of the
skull is straight in P. antiquus, whereas it is concave in P. longi-
collum (Fraas, 1878:pl. 22; Meyer, 1859:pl. Figs. 1 and 2). The
nasoantorbital fenestra is longer in P. antiquus (subadults),
about two times the orbit length, whereas the nasoantorbital
fenestra is just a little longer than the orbit in P. longicollum.
Moreover there is no long nasal process within this fenestra in P.
longicollum, in contrast to the presence of this feature in P.
antiquus. The tooth shape seems different between the two spe-
cies, with more slender and longer teeth in P. longicollum than in
P. antiquus. The tooth row is less extended in P. longicollum,
reaching its posterior extent well anterior to the anterior margin
of the nasoantorbital fenestra, when the tooth row ends at the
level of or posterior to the anterior margin of the nasoantorbital
fenestra in P. antiquus. All these characters demonstrate that P.
antiquus and P. longicollum are not conspecific.
For Germanodactylus, the differences are more important,
with a shorter distance between the tip of the snout and the
anterior margin of the nasoantorbital fenestra (33% of skull
length in G. rhamphastinus, MCZ 1886, and 38% in G. cristatus,
1892 IV 1) than in P. antiquus (49.5%, AS I 739). The quadrate
is less inclined compared to the anterior base of skull in Germa-
nodactylus, and the nasoantorbital fenestra is higher posteriorly,
with a more triangular shape than in P. antiquus. Therefore, the
Germanodactylus are two distinct species from P. antiquus.
Other Pterodactyloids
On the graph (Fig. 10), there are not enough data to determine
if Pterodactylus micronyx is lined up with Ctenochasma roemeri,
C. sp. or Gnathosaurus subulatus.
There is no doubt that P. micronyx is a different taxon than P.
FIGURE 9. Pterodactylus “kochi”, 1878 VII 1, Bayerische Staatssammlung fu¨r Pala¨ontologie und historische Geologie, Mu¨nchen (arrow indicates
fossilization artifact) (Wellnhofer, 1970).
JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 24, NO. 3, 2004550
antiquus (and P. ‘kochi’) (Wellnhofer, 1970; Bennett, 1996b).
Moreover, some features show that Pterodactylus micronyx is a
juvenile, such as an enlarged orbit larger than the nasoantorbital
fenestra, a very reduced nasoantorbital fenestra and very thin,
short and anteriorly located teeth. These features are also visible
on the juveniles of the other species (“Pterodactylus elegans”,“P.
kochi”).
From a morphological point of view, the teeth of Pterodactylus
micronyx are thin, seem laterally directed (but to a lesser extent
than in Ctenochasma) and its squamosal is rounded and not in
continuity with the quadrate and the parietal, as in Ctenochasma
sp. The same characters can be seen in Gnathosaurus subulatus,
which enabled Bennett (1996b) to suggest that Pterodactylus mi-
cronyx might represent a juvenile form of Gnathosaurus subu-
latus. Comparisons of P. micronyx with Ctenochasma roemeri
cannot be done because only the anterior part of the C. roemeri
mandible is known, and this species is distinct from C. sp. (see
above). It is possible that P. micronyx is a juvenile of C. roemeri,
C. sp. or G. subulatus, but no morphological characters permit it
to be linked to one of these species. More data are needed to
determine with certainty which species is the adult of P. micro-
nyx. The data for Gnathosaurus subulatus plot with those of
Pterodactylus kochi and Pterodactylus antiquus (Fig. 7). How-
ever, too many morphological differences exist between these
taxa, such as the presence of shorter and more massive teeth in
Pterodactylus, precluding G. subulatus to belong to the same
taxon, namely P. antiquus.Cycnorhamphus has not been dis-
cussed in this study, but its teeth, which are not numerous and
are situated only on the anteriormost part of the snout, clearly
demonstrate its specific validity as compared to the species dis-
cussed above.
CONCLUSIONS
This study using an original method of analysis provides a
basis for a taxonomic revision of Late Jurassic Pterodactyloidea
of Europe, supporting the validity of the species C. elegans and
P. antiquus. More data are needed to resolve the possible syn-
onymies of the remaining taxa
According to the results of the analysis, the genus Pterodac-
tylus is composed by only two species (Pterodactylus antiquus
and Pterodactylus longicollum), whereas the genus Ctenochasma
includes three species (Ctenochasma roemeri,Ctenochasma el-
egans, and Ctenochasma sp.), and Germanodactylus is a valid
taxa.
The systematics of pterosaurs does not seem definitively es-
tablished, since a simple statistical study determined the syn-
onymy between some species: Pterodactylus elegans,Cteno-
chasma gracile and Ctenochasma porocristata on the one hand,
Pterodactylus antiquus and Pterodactylus kochi on the other
hand. Some problems remain with P. micronyx, a species com-
posed only of juveniles, but it is not possible to determine if the
adult form is C. roemeri,C. sp., or G. subulatus.
ACKNOWLEDGEMENTS
First, I thank the anonymous referee for his comments which
enabled me to increase the quality of this work. Many thanks to
Dr. Christopher Bennett, whose numerous suggestions, com-
ments and criticisms improved this work significantly. Dr. Phil-
lipe Taquet is thanked for giving me permission to work on this
specimen, which he found some years ago. I am grateful to Mr.
Marc Barbier, from the Muse´e Municipal of St-Dizier, for his
welcome and access to the collection. I should like also to thank
FIGURE 10. Diagram comparing the skull length and the number of teeth for different species. Continuous line is regression for P. micronyx +C.
sp. (R
2
⳱0.9857), long discontinuous line is for P. micronyx +C. roemeri (R
2
⳱0.9834), and short discontinuous line is for P. micronyx +Gn.
subulathus (R
2
⳱0.9383).
JOUVE—ACTENOCHASMA SKULL FROM FRANCE 551
Nathalie Bardet for reading this manuscript and offering her
advice. Many thanks to Dr. Michael Parrish who improved my
English. The high quality photographs of the specimen were
made by Mr. Denis Serrette; he is thanked, along with all people
of the Paleontological Laboratory of MNHN.
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Received 9 August 2001; accepted 26 November 2003.
APPENDIX 1
List of data used in the statistical analysis, with inventory number,
repository institution and origin of data for each specimen.
Abbreviations:
BSt: Bayerische Staatssammlung fu¨r Pala¨ontologie und historische Ge-
ologie, Mu¨nchen, Germany.
GIE: Geologisches Institut der Universita¨t Erlangen, Germany.
JM: Jura Museum, Eichsta¨tt, Germany.
MBH: Museum Berge` r, Harthof bei Eichsta¨tt, Germany.
MCZ: Museum of Comparative Zoology, Cambridge, Massachusetts,
USA.
MMSD: Muse´e Municipal de Saint-Dizier, France.
MNHN: Muse´um National d’Histoire Naturelle de Paris, France.
NHMW: Naturhistorisches Museum, Wien, Austria.
PIU: Pala¨ontologisches Institut der Universita¨t Uppsala, Sweeden.
PM: Pala¨ontologisches Institut und Museum der Universita¨tZu¨rich,
Switzerland.
PTH: Philisophisch-Theologische Hochschule, Eichsta¨tt, Germany.
RM: Rijksmuseum van Geologie en Mineralogie, Leiden, Netherlands.
SM: Natur-Museum und Forschungsinstitut Senckenberg, Frankfurt,
Germany.
SMS: Staatliches Museum fu¨r Naturkunde in Stuttgart, Germany.
TM: Teyler-Museum, Haarlem, Netherlands.
UB: Katedra geologie a paleontologie der Universita¨t Bru¨nn, USSR.
JOUVE—ACTENOCHASMA SKULL FROM FRANCE 553
APPENDIX 1. (Continued)
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