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Journal of Vertebrate Paleontology
ISSN: 0272-4634 (Print) 1937-2809 (Online) Journal homepage: http://www.tandfonline.com/loi/ujvp20
A new archaeopterodactyloid pterosaur
from the Jiufotang Formation of western
Liaoning, China, with a comparison of sterna in
Pterodactylomorpha
Shunxing Jiang, Xin Cheng, Yingxia Ma & Xiaolin Wang
To cite this article: Shunxing Jiang, Xin Cheng, Yingxia Ma & Xiaolin Wang (2016): A new
archaeopterodactyloid pterosaur from the Jiufotang Formation of western Liaoning, China,
with a comparison of sterna in Pterodactylomorpha, Journal of Vertebrate Paleontology, DOI:
10.1080/02724634.2016.1212058
To link to this article: http://dx.doi.org/10.1080/02724634.2016.1212058
Published online: 13 Sep 2016.
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ARTICLE
A NEW ARCHAEOPTERODACTYLOID PTEROSAUR FROM THE JIUFOTANG FORMATION
OF WESTERN LIAONING, CHINA, WITH A COMPARISON OF STERNA IN
PTERODACTYLOMORPHA
SHUNXING JIANG,
1,2
XIN CHENG,
1,3
YINGXIA MA,
4
and XIAOLIN WANG*
,1,2
1
Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology,
Chinese Academy of Sciences, P.O. Box 643, Beijing 100044, China, jiangshunxing@ivpp.ac.cn; chengxin.shenzhishe@gmail.com;
wangxiaolin@ivpp.ac.cn;
2
University of Chinese Academy of Sciences, Beijing 100049, China;
3
Laboratory of Systematics and Taphonomy of Fossil Vertebrates, Department of Geology and Paleontology, Museu Nacional/
Universidade Federal do Rio de Janeiro. Quinta da Boa Vista s/n, S~
ao Crist
ov~
ao, 20940–040, Rio de Janeiro, Rio de Janeiro, Brazil;
4
Hami Museum, Hami 839000, China, 495187274@qq.com
ABSTRACT—Eleven species of archaeopterodactyloid pterosaurs have been reported in China, mostly from the Yixian
Formation of western Liaoning. The first uncontroversial archaeopterodactyloid from the Jiufotang Formation is described
here. A new genus and species, Forfexopterus jeholensis, is erected on the basis of a unique combination of characters and
one autapomorphy: the first wing phalanx is shorter than the second, but longer than the third. The sternum of Forfexopterus
is nearly complete and provides the first incontrovertible evidence about the position of sternocoracoid articulations in the
Archaeopterodactyloidea. A preliminary geometric morphometric analysis of sterna was carried out with data from 17
species of Pterodactylomorpha. The results document the variation in the shape of the sternum, including the length of the
cristospine, the shapes of the lateral, posterior, and anterior margins, and the constriction and expansion of the cristospine.
These characters can be used to compare sterna in different pterosaur taxa.
Citation for this article: Jiang, S., X. Cheng, Y. Ma, and X. Wang. 2016. A new archaeopterodactyloid pterosaur from the
Jiufotang Formation of western Liaoning, China, with a comparison of sterna in Pterodactylomorpha. Journal of Vertebrate
Paleontology. DOI: 10.1080/02724634.2016.1212058.
http://zoobank.org/urn:lsid:zoobank.org:pub:41B25239-6220-4006-82CD-1624B36A38EB
INTRODUCTION
Pterosauria is an important group of reptiles that were the first
vertebrates to evolve powered flight. Because their bones are
fragile, with an extremely thin bone wall (Ricql
es et al., 2000;
Steel, 2008), pterosaur fossils are rare worldwide (Barrett et al.,
2008) and often fragmentary. Indeed, only a few deposits yield
abundant and complete pterosaur fossils, with the Jehol Biota
being one such Lagerst€
atte. Pterosaur fossils have been discov-
ered in two formations of the Jehol Group: the stratigraphically
lower Yixian Formation, in which archaeopterodactyloids domi-
nate, and the stratigraphically higher Jiufotang Formation, in
which dsungaripteroids dominate (Wang, Cheng, et al., 2014).
The first archaeopterodactyloid pterosaur to be reported
from China was Huanhepterus quingyangensis from the Lower
Cretaceous Huanhe Formation (Dong, 1982; Wang et al.,
2014a). Most archaeopterodactyloids discovered in the Jehol
Biota, including Eosipterus yangi, Beipiaopterus chenianus,
Zhenyuanopterus longirostris, Boreopterus cuiae, Feilongus
youngi, Gegepterus changae, Elanodactylus prolatus, Pterofil-
trus qiui,andBoreopterus giganticus, come from the lower
part of the Yixian Formation (Ji and Ji, 1997; L€
u, 2003, 2010;
L€
u and Ji, 2005; Wang et al., 2005, 2007; Andres and Ji, 2008;
Jiang and Wang, 2011a; Jiang et al., 2014), the absolute age of
which is 125 Ma (Swisher et al., 2002). Cathayopterus grabaui
and Gladocephaloideus jingangshanensis are from the middle
and upper parts of the Yixian Formation (Wang and Zhou,
2006; L€
u et al., 2012a), with absolute ages of 122 and 121 Ma
(Smith et al., 1995), respectively. Although Moganopterus
zhuianus was reported as having been collected from the Yix-
ian Formation (L€
u et al., 2012b), many other vertebrate fossils
from its type locality, Xiaosanjiazi Village, Lamadong Town,
are considered to be from the Jiufotang Formation (Zhou,
2010; Evans and Wang, 2012; Li et al., 2014). We have previ-
ously investigated this locality and collected tuff samples from
above the fossil-bearing shale for laser ablation sampling and
multiple collector inductively coupled plasma mass spectrome-
try (LA-MC-ICPMS) U-Pb zircon analysis. Our result was 120
§1.0 Ma (unpubl. data), which is the same as the age
reported for the Jiufotang Formation at another locality (He
et al., 2004). Hence, Moganopterus is probably derived from
the Jiufotang Formation, rather than the Yixian Formation as
originally reported.
Recently, a second archaeopterodactyloid specimen from the
Jiufotang Formation was collected at the Xiaotaizi locality,
which is less than 500 m away from the locality that yielded
Moganopterus. In this paper, we describe this new archaeoptero-
dactyloid pterosaur, which is the most complete specimen of this
group discovered in China, and present a preliminary compari-
son of Pterodactylomorpha sterna.
*Corresponding author.
Color versions of one or more of the figures in this article can be found
online at www.tandfonline.com/ujvp.
Journal of Vertebrate Paleontology e1212058 (12 pages)
Óby the Society of Vertebrate Paleontology
DOI: 10.1080/02724634.2016.1212058
METHODS
The new specimen reported here was collected by a local
farmer, who told us where he had discovered the specimen. We
confirmed the fossil locality and horizon through our own field
work. Unfortunately, the farmer had removed some of the
matrix covering the fossil with his own tools, and in doing so had
damaged the surface of the specimen. The specimen was pre-
pared by a technician who removed the matrix and glued three
major parts back together. All fossil elements preserved in these
pieces clearly belong to the same individual.
Geometric Morphometric (GM) Analysis
Geometric morphometric (GM) analysis using a two-dimen-
sional (2D) approach was carried out on the half outline of
sterna for 17 species of the Pterodactylomorpha (sensu Andres
et al., 2014), for all of which sterna were completely preserved or
have been confidently reconstructed (Fig. 1). Geometric mor-
phometric analysis aims to quantitatively analyze shape variation
among specimens based on landmark and/or semi-landmark
coordinate data (Adams et al., 2004; Zelditch et al., 2004). In
this analysis, we assumed that the left and right outlines of the
sterna were symmetrical, and that the outlines in dorsal and ven-
tral views were the same. Considering that specimens with com-
plete sterna are rare, we did not analyze the left and right halves
separately, although the sternocoracoid articulations are asym-
metric in some taxa, making the right and left outlines have a
slight difference.
In this analysis, four landmarks were chosen: (1) the anterior
tip of the cristospine; (2) the widest point of the anterior margin;
(3) the posterior point of the lateral margin; and (4) the midpoint
of the posterior margin (Fig. 1). Some other points, such as the
posterior end of the keel and the anterior point of the pneumatic
foramen in the sternal plate, would also make suitable land-
marks, but were not chosen because they could not be identified
on the majority of the sterna assessed.
The margin of the sternum between the first and second land-
marks was divided into 19 equidistant parts using the program
TpsDig2 (Rohlf, 1998a), and the dividing points were treated as
semi-landmarks (Fig. 1), the positions of which depend on other
landmarks and thus contain less shape information. The outlines
between the second and third landmarks and the third and fourth
landmarks were divided into seven and nine equidistant parts,
respectively. Equidistant semi-landmarks do not necessarily
show geometric or biological correspondence across specimens.
Therefore, the spacing of semi-landmarks is arbitrary (Gunz and
Mitteroecker, 2013). However, the effect of the arbitrary spacing
could be removed by using the sliding technique, which mini-
mizes the Procrustes distance of the semi-landmarks relative to
the average shape of the entire sample (Gunz and Mitteroecker,
2013).
The program TpsRelw (Rohlf, 1998b) was used to conduct
superimposition on the raw coordinate data with the method of
generalized Procrustes analysis (GPA), and the relative warp
analysis (RWA; or principal component analysis, PCA) of shape
variables. The GPA method minimizes the total sum of the
squared distances between corresponding landmarks (Hammer
and Harper, 2006). RWA (PCA) finds principal components of
the thin-plate spline deformations from average shape to each
individual shape (Hammer and Harper, 2006).
SYSTEMATIC PALEONTOLOGY
PTEROSAURIA Kaup, 1834
PTERODACTYLOIDEA Plieninger, 1901
ARCHAEOPTERODACTYLOIDEA Kellner, 2003
CTENOCHASMATIDAE Nopcsa, 1928, sensu Andres et al.,
2014
FORFEXOPTERUS JEHOLENSIS, gen. et sp. nov.
(Figs. 2–5)
Etymology—‘forfex,’ Latin, meaning scissors, referring to the
shape of the upper and lower jaws; ‘pterus,’ Greek, meaning
‘wings’; ‘jehol,’ referring to the ancient name of the region where
the specimen was collected.
Holotype—The specimen is housed at the Hami Museum
(HM V20), Hami, China. The specimen contains most parts of
the skull and mandible and a nearly complete postcranial
skeleton.
Locality and Horizon—Xiaotaizi, Lamadong, Jianchang,
Liaoning Province, China; Jiufotang Formation, late Early Cre-
taceous (120 §1.0 Ma).
Diagnosis—Forfexopterus jeholensis is a large-sized archaeop-
terodactyloid, which can be distinguished from all other mem-
bers of the clade by a single autapomorphy: the first wing
phalanx is shorter than the second phalanx but longer than the
third. The specimen can be further distinguished from other
archaeopterodactyloids on the basis of the following combina-
tion of characters: teeth are slender, with a total count of approx-
imately 120 for the upper and lower jaws; tooth row occupying
more than a third of the skull length, but ending anterior to the
anterior margin of the nasoantorbital fenestra; cristospine long;
sternocoracoid articulations asymmetric; and coracoid flange
present.
DESCRIPTION AND COMPARISON
The holotype of Forfexopterus is nearly completely preserved,
but is lacking the posterior part of the skull, some cervical verte-
brae, most sacral verterbae, all dorsal and caudal vertebrae, and
part of the pelvis (Figs. 2, 3). It represents a large individual,
with a wingspan of 3 m. Some bones that are typically fused in
adult pterosaurs remain unfused in this specimen, such as the
axis and atlas, scapula and coracoid, humerus shaft and its distal
epiphysis, and first wing phalanx and its extensor tendon process.
These observations indicate that this specimen is not an adult
individual (Bennett, 1993, 1996; Kellner and Tomida, 2000; Kell-
ner, 2015). The syncarpals are fused, which occurs at the third of
the six ontogenetic stages for pterosaurs identified by Kellner
(2015), indicating that the specimen is older than a juvenile (the
second stage). Hence, this is a subadult individual.
Skull—The skull is compressed laterally (Fig. 4A; Table 1). It
is low and elongated, with an estimated length of 510 mm. The
nasoantorbital fenestra is incomplete; its estimated length is
112.3 mm, occupying 22.0% of the skull length. Most elements
posterior to the nasoantorbital fenestra are not preserved. Only
the anterior part of the left quadrate is preserved, and it connects
with the articular. The occipital region is displaced from its natu-
ral position and is now preserved next to the nasoantorbital
fenestra. The occipital condyle is nearly complete and is fused
with the opisthotic and exoccipital. The premaxilla is extremely
elongated and lacks a crest.
Mandible—The mandible is complete, although the left ramus
is overlain by the right. Because the posterior region of the right
ramus was overturned during preservation, both rami are
exposed in medial view (Fig. 4B; Table 1). The adductor fossa is
oblate and very small. The angular and surangular form the ven-
tral and dorsal margins of the posterior mandible, respectively.
The surangular occupies more than one third of the entire length
of the mandible. The articular is ventrally inclined and forms the
curved ventral margin of the mandible. There is no crest on the
mandible.
Dentition—The teeth in both the upper and lower jaws are
slender and slightly curved (Fig. 4; Table 1). Because the tips of
the upper and lower jaws are missing and the last one or two
alveoli in the lower jaw are overlain by other bones, the exact
Jiang et al.—Forfexopterus from China (e1212058-2)
FIGURE 1. Sterna of pterosaurs sampled by our geometric morphometric analysis, showing landmarks (blue and large) and semi-landmarks (red and
small). A,Forfexopterus jeholensis, gen. et sp. nov. (reversed); B,Darwinopterus linglongtaensis (after Wang et al., 2010); C,Darwinopterus robust-
dens (after L€
u et al., 2011); D,Kunpengopterus (after Wang et al., 2010); E,Pterodactylus antiquus (after Wellnhofer, 1970); F,Ardeadactylus longi-
collum (after Meyer, 1854); G,Auruazhdarcho primordius (after Frey et al., 2011); H,Haopterus (reversed, after Wang and L€
u, 2001); I,Anhanguera
piscator (after Kellner and Tomida, 2000); J,Muzquizopteryx (after Frey et al., 2006); K,Nurhachius (after Wang et al., 2005); L,Nyctosaurus gracilis
(after Wilston, 1903); M,Pteranodon (after Eaton, 1903); N,Dsungaripterus (reversed; after Young, 1973); O,Eopteranodon (reversed, after L€
u et al.,
2006); P,Jidapterus (Dong et al., 2003); Q,Tapejara wellnhoferi (after Eck et al., 2011). Not to scale.
Jiang et al.—Forfexopterus from China (e1212058-3)
number of teeth is unknown. However, we estimate 30 and 28
per side for the upper and lower jaws, respectively. The sixth to
10th teeth (see Fig. 4 for our estimated tooth positions) are lon-
ger than the other teeth in both upper and lower jaws. The teeth
become apicobasally shorter posteriorly starting from the 10th
tooth. Each of the anterior teeth is located within an alveolus,
and the last few teeth are located in a groove formed by their
alveoli. The surface of each tooth is smooth, and no longitudinal
striations can be observed, similar to the tooth morphology in
many ctenochasmatids such as Ctenochasma elegans, Cathayop-
terus, Gegepterus, and Pterofiltrus (Wagner, 1861; Wang and
Zhou, 2006; Wang et al., 2007; Jiang and Wang, 2011a). None-
theless, the teeth of HM V20 curve more strongly than those of
other ctenochasmatids. Additionally, the number of teeth is simi-
lar to that of Huanhepterus, Gnathosaurus, Plataleorhynchus,
Boreopterus, and Pterofiltrus (Dong, 1982; Howse and Milner,
1995; L€
u and Ji, 2005; Jiang and Wang, 2011a), but there are
fewer teeth than in Cathayopterus and Gegepterus (Wang and
Zhou, 2006; Wang et al., 2007), and more teeth than in Feilon-
gus, Gladocephaloideus, and Moganopterus (Wang et al., 2005;
L€
u et al., 2012a, 2012b). The tooth row ends anterior to the ante-
rior margin of the nasoantorbital fenestra, which is similar to
Huanhepterus, Cathayopterus, and Gegepterus (Dong, 1982;
Wang and Zhou, 2006; Wang et al., 2007), but is a longer tooth
row than in Feilongus, Gladocephaloideus, and Moganopterus
(Wang et al., 2005; L€
u et al., 2012a, 2012b), and a shorter one
than in Gnathosaurus, Pterodaustro, Ctenochasma, and boreop-
terids (Meyer, 1834; Sanchez, 1973; L€
u and Ji, 2005; Bennett,
2007; L€
u, 2010; Jiang et al., 2014).
Vertebrae—The second to seventh cervical vertebrae and one
sacral vertebra are preserved (Figs. 2, 3, 5C; Table 2). The axis is
short, and the neural spine is low, differing from the high neural
spine present in the Boreopteridae (L€
u and Ji, 2005; L€
u, 2010;
Jiang et al., 2014) and the knob-like expansion in Gegepterus
(Wang et al., 2007), but similar to the axis of Moganopterus (L€
u,
et al., 2012b). All cervicals are preserved in lateral view and are
elongate with a reduced neural spine. Cervicals 2 to 4 are articu-
lated and complete, but the anterior part of cervical 5 is incom-
plete; the posterior part is visible in dorsal view and shows well-
developed postzygapophyses and postexapophyses (Fig. 5C).
FIGURE 2. Forfexopterus jeholensis, gen. et sp. nov., HM V20 (holotype). Scale bar equals 100 mm.
Jiang et al.—Forfexopterus from China (e1212058-4)
In cervical 5, the width of the element at midlength, the width
between the postzygapophyses, and the width between the
postexapophyses are 22.7, 16.0, and 33.9 mm, respectively. The
ratio of the anteroposterior length of the vertebra to its width at
mid-length is 4.7, which is similar to the condition in most
archaeopterodactyloids, such as Beipiaopterus (3.4 for cervical
7), Gegepterus (4.4), Elanodactylus (4.0 for cervical 7), and Gla-
docephaloideus (3.1 for cervical 3) (L€
u, 2003; Wang et al., 2007;
Andres and Ji, 2008; L€
u et al., 2012a), but not as elongated as in
Huanhepterus (Dong, 1982) and Moganopterus (L€
u, Ji, et al.,
2012), and much more elongated than in boreopterids (L€
u and
Ji, 2005; L€
u, 2010). Cervical 5 has two rod-like elements below
the vertebral centrum, which are interpreted as cervical ribs.
Cervical ribs are also reported in Beipiaopterus and Gegepterus
(L€
u, 2003; Wang et al., 2007). Cervicals 6 and 7 are similar in
morphology to cervical 5, but lack ribs. The ratio of the centrum
length to its height in cervicals 3–7 is 3.9, 6.6, 5.1, 4.5, and 4.7,
respectively. The presence of lateral foramina on the centra of
the cervicals is difficult to determine because their surfaces are
crushed.
The single preserved sacral vertebra centrum is 11.9 mm long
and 8.0 mm wide. The transverse processes are developed and
are longer than the centrum (Figs. 2, 3); each process extends lat-
erally for 30.7 mm. There is a stick-like bone near the left tibia
that is interpreted as the first dorsal rib. This bone is robust and
has two articulation facets on the proximal end; the anterior and
posterior parts of this bone form an angle of approximately 150
to one another.
Sternum—The sternum is well preserved and is exposed in
dorsal view (Fig. 5A, B). The length is slightly greater than the
width (108.9 versus 100.9 mm). The cristospine accounts for
approximately one third of the length of the entire sternum.
There is a low ridge on the middle of the anterior cristospine,
which tapers anteriorly. There are two articular facets for
FIGURE 3. Line drawing of Forfexopterus jeholensis, gen. et sp. nov., HM V20 (holotype). Abbreviations:afo, adductor fossa; art, articular; ax, axis;
car, carpal; cor, coracoid; cv3–7, third to seventh cervical vertebrae; dri, dorsal rib; fe, femur; fi, fibula; hu, humerus; man, mandible; mcI–IV, metacar-
pals I–IV; mtI–V, metatarsals I–V; naof, nasoantorbital fenestra; oc, occipital condyle; pel, pelvis; phd1–3, manual digits I–III; ph1–4d4, first to fourth
phalanges of manual digit IV; pra, prearticular; pt, pteroid; q, quadrate; ra, radius; san, surangular; sca, scapula; sk, skull; st, sternum; sv, sacral verte-
bra; tar, tarsal; te, teeth; ti, tibia; ul, ulna; ?, uncertain; l, left; r, right. Scale bar equals 100 mm.
Jiang et al.—Forfexopterus from China (e1212058-5)
coracoids on the posterior cristospine; the right one is positioned
anterior to the left one. Both the facets are oval and nearly flat-
tened, and each one is as wide as the cristospine. Although some
incomplete sterna of archaeopterodactyloids have been reported
(Dong, 1982; Wang et al., 2007; Andres and Ji, 2008), this is the
first specimen with a sternum providing incontrovertible evi-
dence about the position of sternocoracoid articulations in this
group. The cristospine is not constricted near the sternal plate.
The plate is fan-like, with its length longer than its width. The
entire plate is thin, except at the anterior margin, which is much
thicker than the other parts. The lateral margins of both sides
are incomplete, and none of the costal articulations is preserved.
The posterior margin is arc-like and lacks the concave structure
in the middle seen in Zhejiangopterus or the convex structure in
Nyctosaurus (Cai and Wei, 1994; Williston, 1901). A large
depression lies behind the anterior margin of the plate, and at
the bottom of this depression, a pneumatic foramen opens into
the body of the cristospine.
Pectoral Girdle—The scapulae and coracoids of both sides
are well preserved; the right scapula is partially overlain by
the left coracoid (Figs. 2, 3; Table 3). The elements are not
fused together on either side. The left coracoid is preserved
in anterior view and the right in posterior view. There is a
ventral process near the articulation of the coracoid with the
scapula, which represents the coracoid flange. A coracoid
flange is also reported in some archaeopterodactyloids, such
as Beipiaopterus and Gegepterus (L€
u, 2003; Wang et al.,
2007), but not in Pterodactylus, Cycnorhamphus,andGerma-
nodactylus (Wellnhofer, 1978). The articulation with the ster-
num is slightly concave. Both scapulae are incomplete and
slightly curved. The entire scapula has a uniform thickness
FIGURE 4. The upper and lower jaws of Forfexopterus jeholensis, gen. et sp. nov., HM V20 (holotype). A, photograph of upper jaw; B, interpretive
drawing of upper jaw; C, photograph of lower jaw; D, interpretive drawing of lower jaw. Numbers indicate the tooth positions. Abbreviations:afo,
adductor fossa; art, articular; bo, basioccipital; d, dentary; eo, exoccipital; m, maxilla; naof, nasoantorbital fenestra; oc, occipital condyle; pm, premax-
illa; pra, prearticular; san, surangular; l, left; r, right. Scale bars equal 100 mm.
TABLE 1. Measurements of the cranial elements in the holotype (HM
V20) of Forfexopterus jeholensis, gen. et sp. nov. (in mm).
Element Length
Skull (pr-sq) 510.0
a
Rostrum (pr-naof) 305.9
a
Nasoantorbital fenestra 112.3
a
Tooth row of the upper jaw 184.8
Lower jaw 434.1
Tooth row of the lower jaw 173.2
a
Estimated length.
Jiang et al.—Forfexopterus from China (e1212058-6)
and does not taper. The scapula is longer than the coracoid,
similar to the condition in Beipiaopterus, Zhenyuanopterus,
and Elanodactylus (L€
u, 2005, 2010; Andres and Ji, 2008).
Humerus—Both humeri are well preserved (Figs. 2, 3, 5D;
Table 3). The right humerus is exposed in dorsal view and is
straight (Fig. 5D); the left is exposed in posteroventral view and
bends slightly along its length, indicating that the humeri bend
ventrally towards their distal ends. The deltopectoral crest is
present on the proximal end of the shaft. The length of the crest
base is 30.0 mm, occupying approximately a quarter of the length
of the shaft, which is similar to the condition in Beipiaopterus
and Zhenyuanopterus (L€
u, 2005, 2010) but shorter than in
Huanhepterus (Dong, 1982) and Elanodactylus (Andres and Ji,
2008), in which the crest base extends for one third of the shaft
length. The crest is slightly curved distally, with the cross-section
gradually tapering from the base to the distal end, which is a
character of ctenochasmatids (Andres et al., 2014). The head of
the humerus cannot be observed. Although crushed, the poste-
rior tuberosity is large and well developed. Two pneumatic
foramina are observed in the humeri: one lies on the posterodor-
sal surface of the left deltopectoral crest base, and the other lies
on the dorsal surface of the right humerus, at one third
of humeral length. The pneumatic foramen near the base of the
deltopectoral crest is similar to that in Boreopterus cuiae and
Elanodactylus (L€
u and Ji, 2005; Andres and Ji, 2008) but has not
been reported in Pterodaustro (Bonaparte, 1970). The distal end
of the humerus has an expanded ectepicondyle, which forms a
130angle with the shaft. One epiphysis can be observed near
FIGURE 5. Postcranial elements of Forfexopterus jeholensis, gen. et sp. nov., HM V20 (holotype). A, photograph of the sternum in dorsal view; B,
photograph of the cristospine of the sternum in dorsal view; C, interpretive drawing of cristospine of the sternum in dorsal view; D, photograph of the
fifth cervical vertebra in dorsolateral view; E, interpretive drawing of the fifth cervical vertebra in dorsolateral view; F, photograph of the right
humerus in dorsal view; G, interpretive drawing of the right humerus in dorsal view. Abbreviations:ac, articulation for coracoid; cri, cervical rib; cs,
cristospine; dep, depression; dpc, deltopectoral crest; ec, ectepicondyle; pf, pneumatic foramen; pl, sternal plate; poex, postexapophysis; poz, postzyga-
pophysis; prz, prezygapophysis; rid, ridge. Scale bars equal 10 mm (B) and 20 mm (A,E,G).
Jiang et al.—Forfexopterus from China (e1212058-7)
the distal end and it is not fused with the shaft of the left
humerus.
Ulna and Radius—Most of the left ulna and radius are over-
lain by other bones, but the right elements are exposed (Figs. 2,
3; Table 3). The ulna and radius are straight, and the diameter of
the ulna is slightly larger than that of the radius, as also reported
in Huanhepterus and Beipiaopterus (Dong, 1982; L€
u, 2005).
However, the diameter of the ulna is about twice that of the
radius in Eosipterus, Boreopterus cuiae, Elanodactylus, and Zhe-
nyuanopterus (Ji and Ji, 1997; L€
u and Ji, 2005; Andres and Ji,
2008; L€
u, 2010). The ulna is more than 150% of the length of the
humerus.
Carpus—Four carpals can be observed in this specimen
(Figs. 2, 3). The carpal surfaces are badly crushed. Two of them
are proximal syncarpals, and two are distal syncarpals.
Metacarpus—Most of the right metacarpals are overlain by
other bones, but the left wing metacarpal is well exposed
(Figs. 2, 3; Table 3). Of the other metacarpals, only metacarpal I
can be observed, and its length is similar to that of the wing
metacarpal. This indicates that it connects with the distal carpals,
but the condition of the other metacarpals is difficult to deter-
mine. Metacarpals I–III of Elanodactylus and Gegepterus con-
nect with the distal carpal (Wang et al., 2007; Andres and Ji,
2008), and in some other archaeopterodactyloids, such as Bor-
eopterus cuiae, at least metacarpal I connects with the distal car-
pal (L€
u and Ji, 2005). Neither end of the wing metacarpal is well
preserved, and only the two condyles of the distal end can be
identified, even though the distal end is overlain by the isolated
extensor tendon process.
Pteroid—Both pteroids are slender (Figs. 2, 3; Table 3); the
right one is straight, and the left one is curved. The pteroids taper
distally, and each has a pointed tip, similar to Zhenyuanopterus
(L€
u, 2010) but unlike the slight expansion knob of Elanodactylus
(Andres and Ji, 2008). The ratio of the length of the pteroid to
the ulna is 46.7%, which is similar to that of boreopterids (41.0–
44.2%; L€
u and Ji, 2005; L€
u, 2010).
Phalanges—The wing phalanges become thinner and more
slender from the first to the fourth (Figs. 2, 3; Table 3); the sec-
ond is the longest, and the first is longer than the third, which has
not been reported in any other archaeopterodactyloid (Dong,
1982; Ji and Ji, 1997; L€
u, 2003; L€
u and Ji, 2005). Only Elanodac-
tylus is similar, with the second phalanx being the longest but the
first shorter than the third (Andres and Ji, 2008). The extensor
tendon processes have ossified but are not fused together with
the first wing phalanx. The articular facets between the wing pha-
langes are nearly flat. The fourth phalanx is curved and tapers
distally with an expanded distal end, similar to Elanodactylus
and Gegepterus (Andres and Ji, 2008; Jiang and Wang, 2011a)
but differing from the pointed tip in Huanhepterus, Eosipterus,
and Boreopterus cuiae (Dong, 1982; Ji and Ji, 1997; L€
u and Ji,
2005). Of the other manual digits, digit I is the shortest, digit III
is the longest, and the phalangeal formula is 2-3-4 for digits I–III.
Each digit ends in a large and curved ungual.
Pelvic Girdle—Only part of an ilium is preserved (Figs. 2, 3).
It is incomplete and has a concave dorsal margin.
Femur—The right femur is preserved in posterior view,
whereas the left femur is exposed in anterolateral view (Figs. 2,
3; Table 3). The shaft of the femur curves slightly anteriorly.
The head is demarcated by a constricted neck, and the proximal
facet of the head is nearly flat, similar to the condition reported
in Huanhepterus and Elanodactylus (Dong, 1982; Andres
and Ji, 2008). The head and shaft form an angle of 130. The
greater trochanter lies on the lateral side of the head. The distal
end of the femur consists of a small medial condyle and a
slightly larger lateral condyle separated by a shallow intercon-
dylar sulcus. The lateral condyle forms a 115angle with the
shaft.
Tibia and Fibula—The tibia is straight and is not fused with the
tarsus to form a tibiotarsus (Figs. 2, 3; Table 3). The tibia is longer
than the femur, as is the case in most other archaeopterodactyloids
(Ji and Ji, 1997; L€
u, 2003; Jiang and Wang, 2011b), with the exception
of boreopterids (L€
uandJi,2005;L
€
u, 2010). The fibula tapers distally,
and its length is approximately 40% that of the tibia, a slightly lower
ratiothaninBeipiaopterus (49%; L€
u 2003) and Gegepterus (44.2%;
Jiang and Wang, 2011b).
Tarsus—The tarsi are incomplete on both sides (Figs. 2, 3).
Only one distal tarsal is preserved on the right side, and it articu-
lates with metatarsals II–IV. One large rounded proximal tarsal
and two slightly smaller distal tarsi are preserved, all of which
are badly crushed.
Metatarsus—All the metatarsals are well preserved, and the
fifth one is reduced (Figs. 2, 3; Table 3). The right metatarsals
are exposed in dorsal view, and the left ones in ventral view.
Metatarsal III is 37.1% the length of the tibia, which is similar to
most other archaeopterodactyloids, such as Beipiaopterus
(37.3%; L€
u, 2003), Gegepterus (39.7%; Jiang and Wang, 2011b),
and Gladocephaloideus (40.2%; L€
u et al., 2012a), but much
longer than that of boreopterids (13–15.6%; L€
u and Ji, 2005; L€
u,
2010).
Pedal Digits—All digits except the fifth are well preserved
(Figs. 2, 3). The phalangeal formula is 2-3-4-5-? for pedal digits
I–V. Each of the unguals has a length of 10 mm, and is 5 mm in
transverse width at its base, and as such are much smaller than
the manual unguls. One and two small phalanges are preserved
in the third and fourth digits, respectively, which indicates that
this specimen is not a very young individual (Kellner and
Tomida, 2000).
TABLE 3. Measurements of postcranial elements in the holotype (HM
V20) of Forfexopterus jeholensis, gen. et sp. nov. (in mm).
Element Left Right
Scapula 80.5 79.5
Coracoid 80.8 82.0
Humerus 117.6 118.3
Radius/ulna 192.2 —
Metacarpal IV 146.4 147.2
Pteroid 81.3
b
89.7
First phalanx of manual digit IV 194.5 191.1
Second phalanx of manual digit IV 208.6 217.6
Third phalanx of manual digit IV 159.6
b
188.8
a
Fourth phalanx of manual digit IV 133.2 135.4
Manual digit I 24.0 / 13.1 23.7 / —
Manual digit II 15.5 / 21.1 / 15.1 12.7 / 21.7 / 16.5
Manual digit III 22.7 / 7.2 / 19.2 /
15.2
14.5
b
/ 8.2 / 20.9 /
16.3
Femur 110.3 109.5
Tibia 178.0 178.2
Fibula 69.9 64.7
Metatarsals I–IV 66.9 / 75.3 / 66.1 /
53.9
68.4 / 72.3 / 64.6 /
55.1
a
Estimated length.
b
Preserved length.
TABLE 2. Measurements of cervical vertebrae in the holotype (HM
V20) of Forfexopterus jeholensis, gen. et sp. nov. (in mm).
Vertebra Length (prz–poz) Height of centrum
Cervical 2 19.4 12.6
Cervical 3 65.4 16.8
Cervical 4 107.6
a
16.4
Cervical 5 106.3 20.8
Cervical 6 101.7 22.4
Cervical 7 83.6 17.7
a
Estimated length.
Jiang et al.—Forfexopterus from China (e1212058-8)
DISCUSSION
The clade Archaeopterodactyloidea was first established by
Kellner (2003) and is similar to the Ctenochasmatoidea (sensu
Unwin, 2003) but with the additional inclusion of the aberrant taxon
Germanodactylus. Both clades have been recovered in various ptero-
saur studies (Andres and Myers, 2013; Andres et al., 2014; Hyder
et al., 2014; Wang et al., 2014b). In the most recent phylogenetic
analysis, Andres et al. (2014) considered the Ctenochasmatoidea to
be an ingroup of the Archaeopterodactyloidea.
The new specimen described herein can be assigned to Ptero-
dactyloidea based on the following characters: an elongated
metacarpal IV and a reduced fifth metatarsal. The elongated cer-
vical vertebrae with a low neural spine and the shape of the del-
topectoral crest indicate that this specimen is a member of
Archaeopterodactyloidea (Kellner, 2003; Andres et al., 2014).
The teeth are slender and needle-like, and some anterior teeth
have a crown height that is four times longer than the width of
the base, which indicates that this specimen can be referred to
Ctenochasmatoidea (Ctenochasmatidae CCycnorhamphus;
sensu Andres et al., 2014). This specimen can be tentatively
assigned to Ctenochasmatidae based on several characters, such
as elongated rostrum (Kellner, 2003; Unwin, 2003; Andres et al.,
2014), number of teeth greater than 100 (Unwin, 2003; Andres
et al., 2014), metatarsal III longer than a third of the length of
tibia (Unwin, 2003), and presence of postexapophyses in the
mid-cervical vertebrae (Andres et al., 2014).
Most members of Archaeopterodactyloidea that have been
described based on nearly complete specimens have been discovered
in Europe and China (Barrett et al., 2008), with the additional dis-
covery of Pterodaustro from a Lower Cretaceous deposit in Argen-
tina (Bonaparte, 1970). Most of the European specimens are from
Upper Jurassic deposits, except for Gnathosaurus macrurus and Pla-
taleorhynchus streptophorodon from the lowermost Cretaceous Pur-
beck Limestone Formation (Howse and Milner, 1995; Barrett et al.,
2008). All the Chinese archaeopterodactyloids originate from Lower
Cretaceous deposits (Wang et al., 2014a).
Pterodaustro is a highly unusual pterosaur that has hundreds of
slender and needle-like teeth in the lower jaw. This morphology
is very different from the type specimen of Forfexopterus. Addi-
tionally, the manual unguals are less than twice the size of the
pedal unguals, and the pneumatic foramen is absent on the dor-
sal surface of the humerus in Pterodaustro (Bonaparte, 1970),
differing from the conditions seen in Forfexopterus.
The archaeopterodactyloid pterosaurs discovered in Europe
are also different from the type specimen of Forfexopterus.Cte-
nochasma has slender teeth, as does Forfexopterus (Meyer, 1851;
Wagner, 1861; Jouve, 2004); however, Ctenochasma has at least
60 teeth on each side of its upper and lower jaws (Bennett,
2007), which is much more than in Forfexopterus. The tooth rows
are also much longer relative to skull length, and the tooth den-
sity of Ctenochasma (2.9–7 teeth/cm; Bennett, 2007) is higher
than that of Forfexopterus (1.6 teeth/cm).
The slender teeth, presence of cervical vertebral postexapophyses,
and presence of the coracoid flange distinguish Forfexopterus from
Pterodactylus (Bennett, 2013a), Cycnorhamphus (Bennett, 2013b),
and Ardeadactylus (Bennett, 2013a). Forfexopterus possesses more
teeth than those three genera, but the tooth row is proportionately
shorter than that of Pterodactylus (Bennett, 2013a) and longer than
that of Cycnorhamphus (Bennett, 2013b).
The slender tooth shape, number of teeth, and tooth row
length in Gnathosaurus and Plataleorhynchus are similar to those
in Forfexopterus (Meyer, 1834; Howse and Milner, 1995). How-
ever, the anterior part of the rostrum is spatulate in the first two
genera (Meyer, 1834; Howse and Milner, 1995), which differs
from the unexpanded rostrum tip in the latter. The preserved
skull of Gnathosaurus subulatus shows a low premaxillary crest
(Meyer, 1834), which is absent in Forfexopterus.
The archaeopterodactyloids discovered in China display high
diversity, but all of them are different from the new specimen.
Huanhepterus was discovered in a different locality to all other
archaeopterodactyloids known from China. This taxon has a
long premaxillary crest starting at the anterior part of the ros-
trum (Dong, 1982), a characteristic that is not present in Forfex-
opterus. The cervical vertebrae are extremely elongated in
Huanhepterus, such that the ratio of anteroposterior length to
width at midlength is about 7 (Dong, 1982), which is not the
case in Forfexopterus. The deltopectoral crest of the humerus in
Huanhepterus is more elongated proximodistally relative to the
shaft than that in Forfexopterus (Dong, 1982).
The Boreopteridae (sensu Jiang et al., 2014), including Boreopte-
rus cuiae, B. giganticus,andZhenyuanopterus longirostris, differ sub-
stantially from the new taxon. The long tooth row, medium-length
mid-cervical vertebrae, high neural spines of the mid-cervicals, and
short tibia and foot relative to the femur in boreopterids are absent
in Forfexopterus (L€
u and Ji, 2005; L€
u, 2010; Jiang et al., 2014).
Both the slender teeth and the number of teeth of Pterofiltrus
are similar to those of Forfexopterus (Jiang and Wang, 2011a).
However, the length of the tooth row is 55.8% that of the skull
in Pterofiltrus (Jiang and Wang, 2011a), which is a much higher
percentage than that of Forfexopterus (36.2%). Moreover, the
tooth density in Pterofiltrus (2.5 teeth/cm; Jiang and Wang,
2011a) is higher than that of Forfexopterus (1.6 teeth/cm).
Feilongus, Gladocephaloideus, and Moganopterus have sub-
stantially fewer teeth than Forfexopterus (Wang et al., 2005; L€
u
et al., 2012a, 2012b). The parietal crests preserved in the first
three genera are absent in the latter due to poor preservation.
However, both Feilongus and Moganopterus have a low premax-
illary crest (Wang et al., 2005; L€
u et al., 2012b), which is not
developed in Forfexopterus. The cervical vertebrae are
extremely elongated in Moganopterus (L€
u et al., 2012b) but less
so in Forfexopterus.
Three archaeopterodactyloids in the Jehol Biota are known only
from postcranial material: Eosipterus, Beipiaopterus,andElano-
dactylus (Ji and Ji, 1997; L€
u, 2003; Andres and Ji, 2008). Beipiaop-
terus has an extremely elongated first wing phalanx, even longer
than the sum of the lengths of the second and third phalanges,
which is unique among Pterosauria (L€
u, 2003). The lengths from
the first to the fourth wing phalanges are in descending order in
most pterodactyloids (Andres et al., 2014; Wang et al., 2014b).
However, the second wing phalanx is the longest one in Forfexop-
terus and Elanodactylus (Andres and Ji, 2008), and in Elanodacty-
lus, the third wing phalanx is even longer than the first one
(Andres and Ji, 2008), which is contrary to the situation in Forfex-
opterus. The ratio of the length of the ulna to the humerus in For-
fexopterus is greater than 1.5, which is much larger than that of
the other archaeopterodactyloids found in China.
Cathayopterus and Gegepterus have more teeth (128 and 150,
respectively) and higher tooth densities (2.7 teeth/cm and 5.25
teeth/cm, respectively) than Forfexopterus (116 teeth, 1.6 teeth/
cm) (Wang and Zhou, 2006; Wang et al., 2007). Gegepterus also
has a low premaxillary crest (Wang et al., 2007), which is not
present in Forfexopterus. The posterior margin of the sternum in
Gegepterus is straight (Wang et al., 2007), whereas it is curved in
Forfexopterus.
Comparison of Sterna—The sterna of extant and extinct birds
are characteristic skeletal elements because they are highly
adapted for flight (Zhang et al., 2011; Zheng et al., 2012, 2014),
and this situation should be similar to that in pterosaurs because
pterosaur sterna are also adapted for flight (Bennett, 2003).
However, specimens of pterosaurs are limited, and sterna are
especially rare. Hence, the sternum is not well known, and well-
preserved sterna are available for only a few taxa, such as Nycto-
saurus, Anhanguera, and Pteranodon (Williston, 1901; Kellner
and Tomida, 2000; Bennett, 2001). Although the specimens from
western Liaoning provide some new information about sterna,
Jiang et al.—Forfexopterus from China (e1212058-9)
most of them are incomplete (Dong, 1982; Dong et al., 2003;
Wang et al., 2005, 2007, 2010).
The pterosaur sternum comprises a cristospine and a sternal
plate. A midline ridge on the anterodorsal part of the cristospine is
present in all well-preserved pterosaurs, such as Forfexopterus,
Nyctosaurus, Istiodactylus latidens, Anhanguera,andPteranodon
(Williston, 1901; Hooley, 1913; Kellner and Tomida, 2000; Bennett,
2001). Posterior to the midline ridge are two articulations for cora-
coids, whose positions are symmetric in Nyctosaurus, Anhanguera,
and Pteranodon (Williston, 1901; Kellner and Tomida, 2000; Ben-
nett, 2001) but asymmetric in Istiodactylus latidens, Dsungaripterus,
Rhamphorhynchus, Azhdarcho, Hamipterus,andForfexopterus
(Hooley, 1913; Young, 1973; Wellnhofer, 1978; Averianov, 2010;
Wang et al., 2014b). These articulations are shallow in Forfexopte-
rus, as they are in many pterosaurs, but they are deep in Istiodacty-
lus latidens, Anhanguera,andPteranodon (Hooley, 1913; Kellner
and Tomida, 2000; Bennett, 2001). A lateral constriction of the
posterior cristospine is found in Istiodactylus latidens, Anhanguera,
Nurhachius, Ornithocheirus,andHamipterus (Hooley, 1913; Kell-
ner and Tomida, 2000; Wang et al., 2005; Rodrigues and Kellner,
2013; Wang et al., 2014b). Although the length of the sternal plate
differs, we found that both lateral margins are nearly parallel to
the midline in all complete specimens. The posterior margins of
the sternal plate can be convex, concave, or straight. In Nyctosau-
rus, there is an apparent xiphoid process that is not reported in any
other pterosaur (Hooley, 1913). However, some small concavities
of the posterior margins are found in Anhanguera, Pteranodon,
Haopterus,andEopteranodon (Kellner and Tomida, 2000; Ben-
nett, 2001; Wang and L€
u, 2001; L€
u et al., 2006), which can be inter-
preted as the suture with the xiphoid process.
Geometric morphometric (GM) analysis was carried out on the
sterna of 17 species in Pterodactylomorpha (Fig. 6, see Methods).
These 17 species can be divided into Haopterus and four clades,
Wukongopteridae, Archaeopterodactyloidea, Pteranodontia, and
Azhdarchoidea, based on previous systematic studies (sensu Andres
et al., 2014). The result of relative warp analysis includes 16 princi-
pal components (PCs), and the first six PCs explain 93.1% of the
total variation. Principal components 1, 2, 3, 4, 5, and 6 account for
37.2%, 31.7%, 11.0%, 6.1%, 3.9%, and 3.2% of the variation,
respectively. PC 1 represents the variation in width relative to length
of the whole sternum. PC 2 represents the variation in length of the
cristospine. PC 3 represents the variation in position of the lateral
margin. PC 4 represents variation of the posterior margin and the
constriction of the base of cristospine. PC 5 represents variation in
length of the anterior margin. PC 6 represents variation of expan-
sion of the sternocoracoid articulation.
Six characteristics of sterna are incorporated into the most
recent phylogenetic analysis (Andres et al., 2014), including
almost all the sternal characters identified in previous phyloge-
netic studies (Bennett, 1994; Kellner, 2003; Unwin, 2003; L€
u
et al., 2010; Andres and Myers, 2013; Wang et al., 2014b). These
characteristics include the shapes of the sternum, cristospine and
sternocoracoid articulation, the position of the articulations, and
the posterior constriction and expansion of the cristospine. The
FIGURE 6. Relative warp analysis of the outlines of the sternum in Pterodactylomorpha. The taxonomic groupings follow Andres et al. (2014). TPS
grids correspond to the extremes of the first six PCs. The percentage of variation is listed below each PC axis. The labels (¡) and (C) indicate the neg-
ative and positive values, respectively. Abbreviations:Anh,Anhanguera piscator;Ard,Ardeadactylus longicollum;Aur,Aurorazhdarcho primordius;
Dal,Darwinopterus linglongtaensis;Dar,Darwinopterus robustodens;Dsu,Dsungaripterus;Eop,Eopteranodon;For,Forfexopterus jeholensis, gen. et
sp. nov.; Hao,Haopterus;Jid,Jidapterus;Kun,Kunpengopterus;Muz,Muzquizopteryx coahuilensis;Nur,Nurhachius;Nyc,Nyctosaurus gracilis;Ptd,
Pterodactylus antiquus;Ptn,Pteranodon;Tap,Tapejara wellnhoferi.
Jiang et al.—Forfexopterus from China (e1212058-10)
shape and the position of sternocoracoid articulation do not
relate to our GM analysis. The shapes of the cristospine are
divided into (0) shallow and elongated and (1) deep and short
(Andres et al., 2014). Cristospine variation can be partly
explained by PC 2 because the depth is not measured by our GM
analysis. The constriction and expansion of the cristospine can
be explained by PCs 4 and 6, respectively. Shape of the sternum
has been divided into (0) narrow, (1) quadrangular, (2) semicir-
cular, and (3) triangular (Andres et al., 2014). These four charac-
ter states are correlated with PC 1. The difference between
states 1, 2, and 3 is the shape of the posterior margin, which can
be explained by PC 4. The difference between states 1 and 3 is
the position of the lateral margins, which can be explained by PC
3. The anterior margin is not considered in the phylogeny of
Andres et al. (2014), although its variation (PC 5) accounts for
3.9% of total variation in our GM analysis. We suggest that in
future analyses, the shape of the sternum should be divided into
three characters: the ratio of the length to width of sternal plate;
the position of the lateral margins; and the shape of the posterior
margin. Based on our analysis, these three characters can explain
most of the observed variation in sternal shape.
ACKNOWLEDGMENTS
We thank L. Xiang (Institute of Vertebrate Paleontology and
Paleoanthropology, Chinese Academy of Sciences) for the prep-
aration of the specimen and S. Xing (IVPP) for his help with the
GM analysis; we also thank L. Xu, S.-H. Jia (Henan Geological
Museum), and C.-L. Sun (Jilin University) for access to ptero-
saur specimens. We would also like to express our gratitude to
the three reviewers and the editor for their comments, which
improved the manuscript. We are also indebted to D. Hone and
the editor R. J. Butler for their polishing of the manuscript and
several comments. This study was supported by the National
Key Basic Research Program of China (2012CB821900), the
National Natural Science Foundation of China (41572020), the
Hundred Talents Project of CAS, the National Science Fund for
Distinguished Young Scholars (40825005), and the Key Labora-
tory of Economic Stratigraphy and Palaeogeography, CAS
(Nanjing Institute of Geology and Palaeontology).
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Submitted June 30, 2015; revisions received March 31, 2016;
accepted April 23, 2016.
Handling editor: Richard Butler.
Jiang et al.—Forfexopterus from China (e1212058-12)
