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Proceedings of the Zoological Institute RAS
Vol. 316, No. 1, 2012, рр. 40–49
УДК 57.072
ORNITHOSTOMA SEDGWICKI – VALID TAXON OF AZHDARCHOID PTEROSAURS
A.O. Averianov
Zoological Institute of the Russian Academy of Sciences, Universitetskaya Emb. 1, 199034 Saint Petersburg, Russia;
e-mail: dzharakuduk@mail.ru
ABSTRACT
Ornithostoma sedgwicki Seeley, 1891 from the Lower Cretaceous (Albian) Cambridge Greensand of England is
represented by edentulous jaw fragments, posterior skull fragment with the supraoccipital crest, and by several
postcranial bones attributed previously to Lonchodectes. Ornithostoma is referred to the Azhdarchoidea based on a
combination of derived characters (teeth absent, middle cervicals moderately elongated, pneumatic foramen on an-
terior side of humerus, large pneumatic foramen on posterior side of femur at greater trochanter) and plesiomorphic
characters (deltopectoral crest not warped, femoral neck to shaft angle less than 145°). The structure of the supraoc-
cipital crest and humerus resembles those in Tapejara, but Ornithostoma differs from that taxon by a strong median
ridge on the occiput presumably associated with a more elongated rostrum. At least three taxa of basal azhdarchoids
were present in the British Lower Cretaceous.
Key words: Azhdarchoidea, Lonchodectes, Early Cretaceous, Ornithostoma, Pterosauria
ORNITHOSTOMA SEDGWICKI – ВАЛИДНЫЙ ТАКСОН АЖДАРХОИДНЫХ
ПТЕРОЗАВРОВ
А.О. Аверьянов
Зоологический институт Российской академии наук, Университетская наб. 1, 199034 Санкт-Петербург, Россия;
e-mail: dzharakuduk@mail.ru
РЕЗЮМЕ
Ornithostoma sedgwicki Seeley, 1891 из нижнемелового (альб) кембриджского зеленого песчаника Англии
представлен фрагментами беззубых челюстей, фрагментом задней части черепа с затылочным гребнем, и
некоторыми костями посткраниального скелета, которые раньше относили к Lonchodectes. Ornithostoma от-
носится к Azhdarchoidea на основании комбинации продвинутых признаков (отсутствие зубов, умеренно
удлиненные среднешейные позвонки, отверстие пневматизации на передней стороне плечевой кости, круп-
ное отверстие пневматизации на задней стороне бедренной кости у большого трохантера) и плезиоморфных
признаков (дельтопекторальный гребень не загнут, угол между шейкой и телом бедренной кости меньше
145°). Строение затылочного гребня и плечевой кости сходно с таковыми у Tapejara, но Ornithostoma отлича-
ется от последнего таксона мощным медиальным гребнем на затылке, предположительно связанным с более
удлиненной ростральной частью черепа. В нижнем мелу Великобритании существовало, по крайней мере,
три таксона базальных аждархоидов.
Ключевые слова: Azhdarchoidea, Lonchodectes, ранний мел, Ornithostoma, Pterosauria
INTRODUCTION
The first well known toothless pterosaur was
Pteranodon Marsh, 1876 from the Late Cretaceous
of North America. The first discovered specimen of
this pterosaur was a wing metacarpal bone described
as Pterodactylus oweni Marsh, 1871 and its toothless
nature was not apparent until discovery of a more
complete cranial material, upon which a new genus,
“pterodactyl lacking teeth” (meaning of the word
Pteranodon) was established in 1876 (see Witton
2010 for the history of discoveries). Seven years
Ornithostoma sedgwicki – valid taxon of azhdarchoid pterosaurs 41
earlier, Seeley in the catalogue of fossils from the
Sedgwick Museum in Cambridge mentioned three
jaw fragments from the phosphorite mines within
the Albian Cambridge Greensand near Cambridge,
England, numbers 1–3 from cabinet J, tablet 16
(Seeley 1869: xvi). He identified these specimens
as “?premaxillary bones” and referred them to Or-
nithocheirus simus (Owen, 1861), establishing a new
genus Ornithocheirus (Seeley 1869: xvi, 6). In the
footnote on page xvi he diagnosed the new genus as
having “no teeth anterior to the palate”. Surprisingly
enough, Seeley referred to plate 2 in Owen (1861),
where the only figured jaw fragment is toothed. On
this and the next pages he provisionally established
two additional species of Ornithocheirus, which were
described later as Ornithocheirus carteri Seeley, 1870
and Ornithocheirus platyrhinus Seeley, 1870. Both are
synonyms of O. simus according to Unwin (2001).
Formally Pterodactylus simus Owen, 1861 should be
considered as a type species for Ornithocheirus Seeley,
1869, the genus of toothed pterosaurs (Unwin 2001),
but Seeley’s original intention evidently was to es-
tablish Ornithocheirus for the toothless pterosaur.
Later Seeley changed his mind and used this name for
the species of toothed pterosaurs (Seeley 1870). This
incongruence was noted and discussed by Hooley
(1914). In a subsequent publication Seeley (1871:
35) introduced a new provisional generic name,
Ornithostoma (meaning “bird mouth”), for these
three edentulous jaw fragments. Of these fragments,
only one, CAMSM B.54485, was figured by Owen
(1859: pl.4, figs 4, 5; see also Unwin 2001: fig. 13),
who identified it as the proximal end of wing-finger
metacarpal. In 1891 Seeley clearly indicated the
latter specimen as the type of Ornithostoma and pro-
posed the species epithet for this taxon, O. sedgwicki
(Seeley 1891: 442). He also concluded that Orni-
thostoma Seeley, 1871 is a senior subjective synonym
of Pteranodon Marsh, 1876, a conclusion accepted
by some previous pterosaur researchers (Williston
1895, 1896, 1897; Bogolubov 1914; Hooley 1914).
However, the available date of publication of Orni-
thostoma is 1891 because in 1871 it was proposed as a
provisional name without naming the second part of
the binomen (ICZN articles 11.5 and 11.9). The two
other edentulous jaw fragments from the Cambridge
Greensand were found in collection in 1986 (Unwin
2001: 212), but were never figured or described.
An important step towards understanding of Or-
nithostoma was made by Hooley in his revision of the
Cambridge Greensand pterosaurs (Hooley 1914).
A most notable achievement was identification of
CAMSM B.54406 as a posterior skull fragment with
the base of the supraoccipital crest (Hooley 1914:
pl. 22, figs 1–3). This specimen was identified previ-
ously as “orbito-ethmo-sphenoid” bone (Seeley 1870:
85–86, pl. 11, figs 7–9).
Two bones identified by Seeley as a sacral verte-
bra and a pelvis fragment (Seeley 1870: pl. 8, fig. 3,
pl. 10, figs 8, 9), Hooley considered to be parts of the
notarium and were referred to Ornithostoma (assum-
ing it is a synonym of Pteranodon). However, Seeley’s
identifications were correct; the pelvis fragment was
mistaken by Hooley for the supraneural plate of the
notarium, confusing the acetabulum with the scapu-
lar facet.
Peculiar elongated vertebrae from Cambridge
Greensand were initially considered to be caudals
(e.g., Owen 1860: pl. 10, figs 35–37; Seeley 1870:
pl.10, figs 13–17). Later Seeley (1875) admitted that
these vertebrae are cervicals. Hooley (1914: 541)
confirmed this identification and concluded that
“the absence of transverse processes and their am-
phiplatyan nature bring them close to Ornithostoma
(Pteranodon).” But transverse processes are absent
(actually extremely reduced and fused with rudi-
mentary cervical ribs) in all Pterodactyloidea (Un-
win 2003). These vertebrae are typically procoelous,
not “amphiplatyan.” Padian (1986: 289) considered
these vertebrae as “Azhdarcho-like cervicals.” Their
similarity with the azhdarchid cervicals also has been
noted by Howse (1986: 320).
Hooley (1914) referred to Ornithostoma a scapu-
locoracoid fragment from Cambridge Greensand
figured by Owen (1859: pl. 3, fig. 1) because of a large
pneumatic foramen between the scapula and coracoid
on the posterior side behind the glenoid. Indeed such
a foramen is characteristic for Pteranodon (Bennett
2001: fig. 65A), but is also found in ornithocheirids
(Wellnhofer 1991: fig. 16d). Hooley (1914) also re-
ferred to Ornithostoma proximal and distal ends of
humeri and ulnae classified in his group B, and proxi-
mal ends of femora attributed to group 1.
The revision made by Hooley was challenged by
Unwin (2001). Although synonymy of Ornithostoma
and Pteranodon was no longer upheld, Unwin sup-
ported referral of Ornithostoma to the Pteranodonti-
dae albeit with reservation. He restricted this taxon
to the three edentulous jaw fragments, including the
holotype CAMSM B.54485, and considered that the
А.О. Аverianov
42
posterior skull fragment CAMSM B.54406 might
be also belong to this species. According to Unwin
(2001), there is no evidence to support referral of
any postcranial bones to Ornithostoma proposed by
Hooley (1914). The elongated cervical vertebrae,
attributed to Ornithostoma by Hooley (1914), and
humerus fragments of group C, not attributed to any
known taxon by Hooley, Unwin (2001) referred to
the Lonchodectidae. Based on this he concluded that
lonchodectids “are certainly not ornithocheiroids”
(Unwin 2001: 208). No rationale was given for these
attributions, however. In a single phylogenetic analy-
sis employing Lonchodectes this taxon was recovered
as a sister taxon to “Anhangueridae” (=Ornithochei-
ridae) (Andres and Ji 2008) within the group equal to
the Ornithocheiroidea of Unwin (2003).
In this report I argue for a new interpretation of
Ornithostoma sedgwicki as an azhdarchoid pterosaur.
I refer to this taxon the holotype rostrum frag-
ment (CAMSM B.54485), posterior skull fragment
(CAMSM B.54406), elongated cervicals and proxi-
mal humerus fragment of Group C of Hooley (1914)
which were referred to Lonchodectes by Unwin
(2001, 2003), and the femur of group 2 (CAMSM
B.54262), not attributed to any particular taxon by
Hooley (1914) and attributed to Lonchodectes sp. by
Unwin (2003).
Institutional abbreviations. AMNH, American
Museum of Natural History, New York, USA; BMNH,
Natural History Museum, London, United Kingdom;
BSP, Bayerische Staatssammlung für Paläontologie
und Geologie, Munich, Germany; CAMSM, Sedg-
wick Museum, Cambridge, United Kingdom; DNPM
MCT, Departamento Nacional da Produção Mineral,
Museu de Ciências da Terra, Rio de Janeiro, Brazil;
GIUA, Geological Institute, University of Amster-
dam, Amsterdam, Netherlands; SMNK, Staatliches
Museum für Naturkunde, Karlsruhe, Germany;
USNM, United States National Museum, Washing-
ton, DC, USA.
SYSTEMATICS
Pterosauria Kaup, 1834
Pterodactyloidea Plieninger, 1901
Azhdarchoidea Nessov, 1984
Ornithostoma sedgwicki Seeley, 1891
Ornithostoma sedgwicki: Seeley 1891: 442.
Ornithostoma seeleyi: Lydekker 1904: 59.
Holotype. CAMSM B.54485, rostrum fragment
(fused premaxillae and maxillae).
Type locality and horizon. A phosphorite mine
near Cambridge, England, United Kingdom; Cam-
bridge Greensand, Lower Cretaceous (Albian).
Diagnosis. Referred to the Azhdarchoidea by the
combination of the following characters: teeth ab-
sent; middle cervicals moderately elongated; lateral
pneumatic foramen on middle cervicals reduced or
absent; pneumatic foramen on ventral side of hu-
merus near the base of humeral neck; deltopectoral
crest of humerus elongated and rounded on distal
end, not warped, with parallel sides; angle of femoral
neck to shaft less than 145°; a large pneumatic fora-
men on posterior side of femur between neck and
greater trochanter. Differs from the Azhdarchidae by
less elongated middle cervicals, with neural arch not
confluent with centrum in middle and neural spine
not reduced; lateral pneumatic foramen variably
present on postaxial cervicals; deltopectoral crest of
humerus proximally placed. Differs from Tupandac-
tylus by frontal not fused with premaxillary crest.
Differs from Tapejara by a strong median ridge on the
occiput presumably associated with a longer rostrum
and supraoccipital crest starting above the orbit. Dif-
fers from both Tupandactylus and Tapejara by more
elongated middle cervicals. Differs from Tupuxuara
by much lower cranial crest above orbit and less
elongated middle cervicals.
Referred specimens. Various phosphorite mines
around Cambridge, Cambridge Greensand: CAMSM
B.54406, posterior skull fragment; CAMSM B.54394
and B.54493, cervical vertebrae; CAMSM B.54081,
right humerus; BMNH 35413, proximal fragment of
right humerus; CAMSM B.54262, proximal part of
right femur.
Comments. The known specimens of Ornithos-
toma sedgwicki show considerable similarity with
recently described taxa from the Yixian (Barremian)
and Jiufotang (Aptian) formations of Liaoning Prov-
ince, China classified currently within the azhdar-
choid family “Chaoyangopteridae” (Dong et al. 2003;
Wang and Zhou 2003; Lü and Ji 2005; Lü and Zhang
2005; Lü et al. 2006, 2008; Zhou 2010). This similar-
ity includes relatively long rostrum, presence of a su-
praoccipital crest at least in some “chaoyangopterids”
(Eopteranodon), moderately elongated middle cer-
vicals, and plesiomorphic structure of the humerus.
Detailed comparison is limited by incompleteness of
the Cambridge Greensand specimens and the state
Ornithostoma sedgwicki – valid taxon of azhdarchoid pterosaurs 43
of preservation of the Liaoning specimens. Also the
taxonomy of the Chinese taxa is quite confusing and
some taxa need a revision. According to Lü et al.
(2008: 892) “members of Chaoyangopteridae are dis-
tinguished from all other pterosaurs by an unusually
slender premaxillary bar bounding the nasoantorbital
opening and extension of the nasoantorbital open-
ing posterior to the jaw joint.” However, both these
characters can be observed only on a single specimen,
the holotype of “Shenzhoupterus chaoyangensis” from
the Jiufotang Formation (Lü et al. 2008: fig. 1). The
holotype is a juvenile specimen and this taxon is
most likely a junior subjective synonym of Chaoyan-
gopterus zhangi Wang et Zhou, 2003 from the same
formation. The second of the mentioned characters
is likely a preservation artifact caused by filling of
the nasoantorbital fenestra by mixture of crushed
cranial, and possibly some postcranial, bones. The
monophyly of the “Chaoyangopteridae” and validity
of some currently recognized taxa referred to this
group remain to be demonstrated.
Distribution. Western Europe; Early Cretaceous
(Albian).
DESCRIPTION AND COMPARISON
Rostrum fragment
The holotype CAMSM B.54485 (Fig. 1) is a small
fragment of an edentulous rostrum. It is roughly
triangular in cross section with convex lateral sides
and concave ventral occlusal side. The dorsal mar-
gin is rounded. In lateral profile the ventral margin
is sligthly convex. The dorsal margin is inclined to
the ventral margin at 12°. If the angle of dorsal and
ventral margin convergence is consistent and the
rostrum tapered in a sharp point, the rostrum tip
would be located anteriorly at a distance about twice
greater than the length of the preserved fragment.
It is likely that the tip of the rostrum was straight
or slightly bent upwards. Near the broken posterior
end of the fragment there is a base of a more abrupt
elevation suggesting presence of a premaxillary crest
on the posterior part of the rostrum. The rostrum is
also widening laterally in the most posterior part of
the fragment, where its width about 1.5 times greater
than the width at the anterior end of the fragment.
Unwin (2001: 212) noted that the rostrum is elon-
gate. He thought that “the rounded, triangular cross-
section of the rostrum [...], which also has low, rounded
marginal ridges [...] clearly distinguish Ornithostoma
from azhdarchids wherein the rostra have concave
lateral surfaces and lack marginal ridges on the jaws
(Wellnhofer and Buffetaut 1999: fig. 4).” However, the
specimen with concave lateral sides to which Unwin is
referring, BSP 1996.I.36, is not a rostrum but a man-
dibular symphysis of a recently described azhdarchid
Alanqa saharica (Ibrahim et al. 2010).
According to Bennett (1994: 17) “Ornithostoma is
quite distinct from Pteranodon.” “The jaws of Pter-
anodon have marginal ridges that extend 3–4 mm
above the floor of roof of the mouth and that are com-
posed of dense bone. The jaw of Ornithostoma lacks
such ridges; instead, the jaw margins are rounded
[...].” Actually CAMSM B.54485 is very similar to
the rostrum fragments of Azhdarcho lancicollis from
the Turonian of Uzbekistan (Averianov 2010). The
only sufficient difference is that no known fragment
of Azhdarcho rostrum has such abrupt lateral widen-
ing at the posterior end as in Ornithostoma.
Skull fragment
The posterior skull fragment CAMSM B.54406
preserves the dorsal roof of the orbit, the occiput and
the base of the supraoccipital crest (Figs 2, 3). The
term “supraoccipital crest” is used here, following
Hooley (1914), in the meaning “crest above the oc-
ciput.” The bone sutures are obliterated. The small
posterior part of the crest may be formed by the su-
praoccipital while the larger part was formed by the
frontal (anteriorly) and parietal (posteriorly). The
space on the ventral side, between the occiput and
Fig. 1. CAMSM B.54485, holotype, rostrum fragment of Orni-
thostoma sedgwicki, in posterior (A), lateral (B), anterior (C), and
ventral (D) views. Reproduced from Owen (1859: pl. 4, figs 4, 5).
Scale bar = 1 cm.
А.О. Аverianov
44
the orbital roof, where there should be a depression
for the cerebral hemispheres, is poorly preserved and
filled by phosphorite. Only the posterior half of the
orbital roof is preserved. Hooley (1914: pl. 22, fig. 1)
oriented CAMSM B.54406 with the posterior orbital
roof facing almost anteriorly and the anterior margin
of the supraoccipital crest almost horizontal. Com-
parison with the posterior skull region in Tapejara
and Pteranodon suggests, however, that this fragment
was oriented more vertically, with the orbital roof
facing anteroventrally (Fig. 2). The construction of
the posterior skull region in Ornithostoma is some-
what intermediate between Tapejara and Pteranodon
(Fig. 2). The supraoccipital crest starts above the
orbit, as in Pteranodon, while in Tapejara it is more
posterior. The upper temporal depression, delimited
dorsally by a prominent ridge between the orbital
margin and the occiput, is about twice smaller than
in Tapejara, but distinctly larger than in Pteranodon.
In Tapejara this depression extends well into the su-
praoccipital crest. In Ornithostoma and Pteranodon it
does not extend onto supraoccipital crest. The crest
of CAMSM B.54406 is rhomboidal in cross section,
with the dorsal part of the rhombus about three times
greater than the ventral part (Hooley 1914: pl. 22,
fig. 3). The lateral angles of the rhombus are made by
the ridges delimiting the dorsal margin of the upper
temporal depression.
In posterior view CAMSM B.54406 is roughly
triangular in shape, tapering dorsally into presumably
long supraoccipital crest (Fig. 3D). The relatively
small foramen magnum is flanked dorsolaterally by
posttemporal fenestrae. In some immature specimens
of pterodactyloids (e.g. Fig. 3C; Kellner and Tomida
2000: fig. 9; Bennett 2001: fig. 16) dorsal to the post-
temporal fenestra there is a large pneumatic foramen.
There is no such foramen in CAMSM B.54406. There
is a prominent median ridge between the foramen
magnum and the dorsal end of the fragment; its thick-
ness increases gradually towards the dorsal end. A
weak median ridge is present in immature specimens
of Pteranodon and Anhanguera (Kellner and Tomida
2000: fig. 9; Bennett 2001: 26). A strong ridge is
present in the presumed azhdarchid Hatzegopteryx
(Buffetaut et al. 2003). The phylogenetic significance
of this character is not clear; the ridge development
is likely correlated with the ontogenetic age of the
animal and its rostrum length (the longer rostrum
would required more powerful neck musculature).
It is notably lacking in the short-faced Tapejara (Fig.
3A–C). The strong median ridge on the occiput of
Ornithostoma may indicate its mature individual
age and a relatively long rostrum. The proportions
of the holotype rostrum fragment also argue for an
elongated rostrum.
Cervical vertebrae
The cervical vertebrae are elongated (length to
middle width ratio is 2.7–2.8; Owen 1860: pl. 10, figs
35–37; Seeley 1870: pl.10, figs 13–17). The elonga-
Fig. 2. Posterior skull of Tapejara wellnhoferi, SMNK PAL 1137
(A, modified from Eck et al. 2011: fig. 2), Ornithostoma sedgwicki
(B, CAMSM B 54.406), and Pteranodon sp., USNM 13868 (C,
modified from Bennett 2001: fig. 11; jugal has been removed), in
lateral view.
Abbreviations: or – orbit; soc – supraoccipital crest; utd – upper
temporal depression. Not to scale.
Ornithostoma sedgwicki – valid taxon of azhdarchoid pterosaurs 45
tion of middle cervicals was independently devel-
oped in the Azhdarchoidea and Ctenochasmatoidea
(Andres and Ji 2008). Ornithostoma shows only the
initial stage of the elongation of middle cervicals.
In the stem azhdarchid Tupuxuara the length to
middle width ratio is 3.2 (GIUA 4895, “paratype”
of Santanadactylus brasilensis; Buisonje 1980: fig. 5,
pl. 2). Otherwise the structure of the cervicals of
Ornithostoma is close to those of Tupuxuara. The
neural spine is not preserved in any specimen, but ap-
parently was blade-like. There is a pair of pneumatic
foramina lateral to the neural canal. In CAMSM
B.54493 there is an additional pair of smaller pneu-
matic foramina ventral to the larger foramina on the
posterior side. The anterior side of this specimen is
obscured by phosphorite. On some specimens there
is a small slit-like pneumatic foramen on the lateral
side of the centrum, while other specimens seem to
be lacking such a foramen. This foramen is present in
the Ornithocheiroidea and Tupuxuara. Its absence on
postaxial cervical vertebrae is a likely synapomorphy
for the Azhdarchidae (Andres and Ji 2008).
Humerus
The humerus CAMSM B.54081 is well preserved
and complete; there is a suture between the shaft and
distal epiphysis suggesting that the individual was
juvenile (Seeley 1870; pl. 4, figs 1, 2; Unwin 2003:
fig. 17j; Witton et al. 2009: fig.5C). This specimen
Fig. 3. Occiput of Tapejara wellnhoferi, SMNK PAL 1137 (A, modified from Eck et al. 2011: fig. 2), AMNH 2440 (B, modified from Welln-
hofer and Kellner 1991: fig. 3b), DNPM MCT 1500–R (C, modified from Kellner 1996: fig. 8) and Ornithostoma sedgwicki (D, CAMSM
B.54.406), in posteroventral view.
Abbreviations: fm – foramen magnum; mr – median ridge; oc – occipital condyle; pf – pneumatic foramen; ptf – posttemporal fenestra;
soc – supraoccipital crest. Not to scale
А.О. Аverianov
46
was chosen as the “type” of group C of the proximal
humerus ends by Hooley (1914). A similar but less
complete specimen from the Cambridge Greensand
(BMNH 35413) was figured by Owen (1861: pl. 3,
fig. 5). The articular surface of the humeral head is
crescentic in proximal view and slightly concave.
The deltopectoral crest is of primitive morphology,
proximally placed, relatively long and straight, with
approximately parallel proximal and distal sides. The
shaft is slender and straight. On the anterior side,
between the bases of the deltopectoral crest and the
humeral head, there is a large pneumatic foramen,
as in Azhdarcho and other azhdarchoids (Averianov
2010). Structurally this specimen is very close to the
humerus from the Barremian Wessex Formation of
Isle of Wight, England, recently described as “the
first record of azhdarchoid pterosaurs in the British
Lower Cretaceous” (Witton et al. 2009: 676, figs
6, 7). Actually the first such record was reported 140
years earlier (Seeley 1869), and reference of some
specimens from Cambridge Greensand to Azhdarchi-
dae was suggested by previous researchers (Padian
1986; Nesov 1991). The Wessex humerus differs by
larger size, more prominent ulnar condyle, relatively
longer and curved deltopectoral crest, which is posi-
tioned sligthly more distal to the humeral head com-
pared with the Cambridge Greensand specimen. All
these characters, however, are likely correlated with
the greater ontogenetic age of the Wessex specimen.
CAMSM B.54081 is also very similar with the hu-
merus of Azhdarcho; in the latter taxon the articula-
tion surface of the humeral head is more concave and
the deltopectoral crest placed slightly more distally
on the shaft (Averianov 2010).
Femur
CAMSM B.54262 is a well preserved proximal
part of the femur (Seeley 1870: pl. 8, figs 7–9). See-
ley (1870) referred this specimen to an unknown
genus, different from Ornithocheirus. Hooley (1914:
556) attributed this specimen to the femur group 2,
of which the taxonomic attribution “must remain
an open question.” Unwin (2003) attributed this
specimen to Lonchodectes sp. without explanation.
CAMSM B.54262 differs from the femora of orni-
thocheirids known from the Cambridge Greensand
by a smaller angle between the neck and the shaft
(137°). According to Andres and Ji (2008) this angle
of 145° or greater is a synapomorphy of the Pter-
anodontidae + Ornithocheiridae. Another notable
difference is a large pneumatic foramen on the poste-
rior side between the bases of the femoral neck and
the greater trochanter. Seeley (1870) interpreted
this hole as a pit for the external obturator muscle.
A smaller pneumatic foramen in this position is
present in Pteranodon and Tapejara (Bennett 2001:
fig. 107B; Eck et al. 2011), but a large slit-like pneu-
matic foramen is characteristic for the Azhdarchidae
(Averianov 2007, 2010). Actually CAMSM B.54262
is almost identical to the femur of Azhdarcho (Averi-
anov 2010: fig. 34A–E). Nesov (1991: 19) previously
suggested that this specimen might belong to an
azhdarchid.
DISCUSSION
The new interpretation of Ornithostoma sedgwicki
proposed herein combines cranial materials previous-
ly referred to that taxon (Seeley 1891; Hooley 1914;
Unwin 2001) with the postcranial materials from the
Cambridge Greensand, attributed by Unwin (2001,
2003) to Lonchodectes. The later attribution had
a strong impact on interpretation of Lonchodectes
as a non-ornithocheiroid pterodactyloid related
to azhdarchoids (Unwin 2001, 2003; Witton et al.
2009), because these postcranial elements (cervi-
cals, humerus, and femur) bear certain azhdarchoid
characters. However, the known cranial remains of
Lonchodectes, exclusively consisting of toothed jaw
fragments, do not show any specific resemblance with
azhdarchoid pterosaurs (Unwin 2001; Martill 2011).
It is more parsimonious to combine the cranial re-
mains from the Cambridge Greensand, including the
toothless holotype of O. sedgwicki and the skull frag-
ment CAMSM B.54406 with Tapejara-like supraoc-
cipital crest, with the postcranial elements from the
same stratigraphic unit bearing certain azhdarchoid
characters (moderately elongated middle cervicals,
humerus with straight deltopectoral crest and pneu-
matic foramen on ventral side, and femur with low
neck to shaft angle and large pneumatic foramen at
the greater trochanter). The postcranial elements of
Lonchodectes might be present in the collection from
the Cambridge Greensand but currently cannot be
differentiated from the postcranial bones of other
ornithocheiroids. Lonchodectes is likely a member
of the Ornithocheiroidea (Andres and Ji 2008), but
possibly deserves separation into a distinct family
because of its peculiar dentition (Unwin 2001, 2003).
Ornithostoma sedgwicki – valid taxon of azhdarchoid pterosaurs 47
Unwin’s interpretation of Lonchodectes influenced
attribution of BMNH 2353, the humerus from the Va-
langinian Hastings Beds Group of Tilgate Forest lo-
cality in West Sussex, England, which is the holotype
of Palaeornis cliftii Mantell, 1844, to the Lonchodec-
tidae (Witton et al. 2009; these authors erroneously
cited Hooley 1914 as the author of the family Lon-
chodectidae). Witton et al. (2009: 681) discussed azh-
darchoid characters of BMNH 2353 and referred it to
the Lonchodectidae because the proximal margins of
the deltopectoral and ulnar crests are “confluent” and
because of an “atypically expanded lateral condyle.”
The formulation of the first character is not correct:
in CAMSM B.54081, referred to Lonchodectes by
Unwin (2001, 2003) and Witton et al. (2009) and to
Ornithostoma here, the deltopectoral and ulnar crests
are not confluent, they are separated by the humeral
head, but their proximal margins are located at the
same level. This is not true for BMNH 2353, where
the deltopectoral crest is distinctly placed more
distally on the shaft, as in azhdarchids (Averianov
2010), with its proximal margin distal to the proximal
margin of the ulnar crest. The lateral expansion of the
distal humerus end is also found in other azhdarchoid
specimens, like USNM 11925, the holotype of “Ben-
nettazhia” oregonensis from the Albian Hudspeth
Formation of Oregon, USA (Gilmore 1928). BMNH
2353, in spite of its relatively small size, is likely a
mature specimen as suggested by accentuated muscle
scars on the deltopectoral crest. Generally it is very
similar to USNM 11925 and may belong to a closely
related taxon of basal azhdarchoids. Because of the
more distal position of the deltopectoral crest this
taxon is more derived than Ornithostoma, which has a
more Tapejara-like humerus.
Witton et al. (2009: figs 6, 7) described another
humerus from the Barremian Wessex Formation of
Isle of Wight, England. It is about 1.5 times larger
than BMNH 2353 and differs by minor details from
the latter. The Wessex specimen also has a more
distally placed deltopectoral crest and belongs to
an azhdarchoid more derived than Ornithostoma.
Thus in the Early Cretaceous on the territory of
modern England there possibly were at least three
azhdarchoid taxa, living in different time intervals
(Valanginian, Barremian, and Albian).
ACKNOWLEDGMENTS
I am grateful to Dr. Daniel Pemberton (Sedgwick
Museum, Cambridge, UK) for access to the specimens
under his care and for consultation about the collection
numbers and to Drs S. Christopher Bennett (Fort Hays
State University, Hays, USA) and Natasha Bakhurina
(Bristol University, Bristol, UK) for reviewing the paper
and linguistic corrections. The laboratory work was sup-
ported by the Russian Foundation for Basic Research
(project 09–04–00222), St. Petersburg State University
(grant NIR 3.39.148.2011), and Ministry of Education and
Science of Russian Federation (contract 16.518.11.7070).
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Submitted February 2, 2012, accepted 27 February, 2012.
