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A new rhamphorhynchid pterosaur (Pterosauria) from Jurassic deposits of Liaoning Province, China

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Compared to pterosaurs from the Early Cretaceous from China, Late Jurassic pterosaurs are relatively rare. A new rhamphorhynchid pterosaur, Orientognathus chaoyngensis gen. et sp. nov., is erected based on an incomplete skeleton from the Upper Jurassic Tuchengzi Formation of Chaoyang, Liaoning Province, China. It is identified by the following characters: the toothless tip of the lower jaw is slightly pointed; the length ratio of wing metacarpal to humerus is 0.38, the ulna is shorter than each wing phalanx and the tibia is nearly equal to femur in length. A phylogenetic analysis recovers Orientognathus chaoyngensis as a rhamphorhynchid pterosaur. Orientognathus chaoyngensis is perhaps the youngest Jurassic pterosaur from western Liaoning Province of China.
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Accepted by S. Brusatte: 24 Nov. 2014; published: 16 Jan. 2015
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A new rhamphorhynchid pterosaur (Pterosauria) from Jurassic deposits
of Liaoning Province, China
JUNCHANG LÜ
1
,
HANYONG PU
2
, LI XU
2
, XUEFANG WEI
3
, HUALI CHANG
2
& MARTIN KUNDRÁT
4
1
Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037 China; Key Laboratory of Stratigraphy and Paleontol-
ogy, Ministry of Land and Resources. E-mail: Lujc2008@126.com; Tel. (fax). 00861068999707
2
Henan Geological Museum, Zhengzhou 450016, Henan Province, China
3
Cores and Samples Center of Land and Resources, China Geological Survey, Sanhe 065201, Hebei Province, China
4
Subdepartment of Evolution and Development, Department of Organismal Biology, Evolutionary Biology Centre, Uppsala University,
Norbyvägen, 18A
, SE-75236 Uppsala, Sweden
Abstract
Compared to pterosaurs from the Early Cretaceous from China, Late Jurassic pterosaurs are relatively rare. A new rham-
phorhynchid pterosaur, Orientognathus chaoyngensis gen. et sp. nov., is erected based on an incomplete skeleton from
the Upper Jurassic Tuchengzi Formation of Chaoyang, Liaoning Province, China. It is identified by the following charac-
ters: the toothless tip of the lower jaw is slightly pointed; the length ratio of wing metacarpal to humerus is 0.38, the ulna
is shorter than each wing phalanx and the tibia is nearly equal to femur in length. A phylogenetic analysis recovers Ori-
entognathus chaoyngensis as a rhamphorhynchid pterosaur. Orientognathus chaoyngensis is perhaps the youngest Juras-
sic pterosaur from western Liaoning Province of China.
Key words: Upper Jurassic, Tuchengzi Formation, Pterosauria, Rhamphorhynchidae
Introduction
Pterosaurs from the Early Cretaceous Jehol Biota of western Liaoning and its surrounding areas are numerous, but
those from the pre-Early Cretaceous deposits of China are rarer, although recently they have been increasing both
in number and variety. The most important discovery among these Jurassic forms is Darwinopterus, a transitional
form with a cranium and cervical series that is of typical pterodactyloid morphology, whereas the remainder of the
postcranial skeleton is almost identical to that of typical long-tailed non-pterodactyloid pterosaurs (Lü et al. 2010a;
2011a). This taxon is pivotal for understanding the evolution of pterodactyloid pterosaurs, and their characteristic
anatomy, from more basal forms. Another spectacular discovery is a female Darwinopterus preserved with an egg,
which has implications for understanding sexual dimorphism and reproductive biology in pterosaurs (Lü et al.
2011b). Other Middle Jurassic pterosaurs from China include the non-pterodactyloid Changchengopterus (Lü
2009); the rhamphorhynchids Pterorhynchus (Czerkas and Ji 2002), which is regarded as close to wukongopterid
pterosaurs (Andres et al. 2014), and Qinglongopterus (Lü et al. 2012); the scaphognathines Fenghuangopterus (Lü
et al. 2010b), Jianchangnathus (Cheng et al. 2012; = Scaphognathus, Bennett 2014), Jianchangopterus (Lü and
Bo 2011c); and the anurognathid Dendrorhynchoides mutodungensis (Lü and Hone 2012).
Here we report a new pre-Cretaceous pterosaur, a rhamphorhynchid designated as the new genus and species
Orientognathus chaoyangensis, from the possible Late Jurassic deposits of Chaoyang, Liaoning Province, of north-
eastern China (Fig. 1). A phylogenetic analysis recovers Orientognathus chaoyangensis as a rhamphorhynchid
pterosaur. The discovery of Orientognathus chaoyangensis provides important new information on the
evolutionary history of the Rhamphorhynchinae and on pterosaur evolution in the Jurassic more generally.
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FIGURE 1. The map of the fossil locality. Solid pentagon represents the fossil site.
Geological setting
The specimen was collected by a local farmer. One of the authors (JL) later visited the fossil locality, guided by the
farmer. Because the specimen was not excavated by a technically accomplished collector, it was heavily damaged
during excavation. During the visit to the site, JL and the collector found a fragment of black bone from a
pterosaur, which is identical to the present specimen in color. Thus, we are confident that the locality the farmer
pinpointed is the locality where the specimen described here was collected. The specimen comes from gray-green
tuffaceous shales (Fig. 2), which based on lithology are most likely belonging to the second member of the Upper
Jurassic Tuchengzi Formation (Bureau of Geology and Mineral Resources of Liaoning Province, 1989).
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FIGURE 2. The strata of the fossil site.
Systematic paleontology
Pterosauria Kaup, 1834
Breviquartossa Unwin, 2003
Rhamphorhynchidae Seeley, 1870 (sensu Unwin, 2003)
Rhamphorhynchinae Nopcsa, 1928 (sensu Unwin, 2003)
Orientognathus chaoyangensis gen. et sp. nov.
Holotype. An incomplete skeleton (41HIII-0418), housed at the Henan Geological Museum, Zhengzhou, Henan
Province.
Type locality and horizon. Jucaigou, Dongshan Village (41º13'9"N, 120º5'51"E), Shengli Town, Chaoyang
County, Liaoning Province; most likely the Tuchengzi Formation (Bureau of Geology and Mineral Resources of
Liaoning Province, 1989) (Figs. 1–2).
Etymology. “Orient” derives from the Latin word oriens meaning "east"; “gnathus” is derived from Greek,
meaning “jaw”. Orientognathus means “pterosaur from the east”. The specific name refers to where the specimen
was found, in Chaoyang.
Diagnosis. A large rhamphorhynchine pterosaur with a wing span about 1.1 meters, bearing the following
unique combination of characters: ratio of wing metacarpal to humerus 0.38 (it is smaller than those in other basal
pterosaurs); the ulna shorter than each wing phalanx (similar to basal pterosaurs such as Preondactylus and
Dimorphodontidae, but it is reversed condition in Scaphognathus); the ulna shorter than tibia (ratio of ulna to tibia
0.92; it is greater than 1 in other rhamphorhynchine pterosaurs); tibia nearly equal to femur in length; length ratio
of pteroid to humerus 0.21.
Description and comparisons. The specimen is not well preserved (Fig. 3; Table 1). The wing span is
estimated to be 1.1 meters. The individual is not ontogenetically mature, based on its unfused extensor tendon
process of the first wing phalanx, and lack of fusion in the scapulocoracoid and pelvis. The skull was heavily
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damaged before burial. All the elements near the braincase are scattered, and it is difficult to identify them. Only
the lower jaws and some teeth can be clearly observed. The third and fourth wing phalanxes were destroyed or lost
as a result of excavation.
TABLE 1. Measurements (mm) of Orientognathus chaoyangensis gen. et sp. nov. (41HIII-0418).
There are about 18 teeth distributed near the rostral portion of the skull. The nearly triangular shaped bone
bearing two teeth is identified as a maxilla in which the teeth are orientated anteroventrally. There is a plate-like
bone with one thickened margin and one articular end, which may be the quadrate. Some teeth are still in the tooth
sockets of the maxillae and dentary. The anterior teeth are relatively small (9 mm in length) and slightly curved,
whereas the posterior teeth are large (20 mm) and nearly straight. The cross-sections of the teeth are oval. The
lower jaw is deep with parallel dorsal and ventral margins. The left ramus of the lower jaw is preserved in situ, but
the right ramus is upside down, which may indicate that the mandibular symphysis was short and the two dentaries
were weakly joined together. The ventral margin of the lower jaw is straight. The distal end of the lower jaw is
short and pointed in lateral view (Fig. 4a).
There are four cervical vertebrae preserved. Although they are poorly preserved, the exposed lateral surface
exhibits clear pneumatic foramina. The dorsal vertebrae are short, and as with the cervical vertebrae, their detailed
structures are not clear. The dorsal ribs are slender. There are four sacral vertebrae (inferred by their position
between the preacetabular processes of the ilia), although they are slightly displaced. The anterior two are fused
and the posterior two are not fused, corroborating the juvenile status of the specimen. The tail is missing its distal
portion. The first two preserved caudal vertebrae are square in shape dorsolateral view. Beginning with the third
caudal, the caudal vertebrae are completely encased by thread-like zygapophyses and elongated haemal arches
(Fig. 4e).
The scapula and coracoid are not fused, which further corroborates the immature ontogenetic stage of the
individual. These bones are not well-preserved. The distal end of the coracoid is missing, and thus its length ratio is
not clear. The left humerus is missing its distal portion and a small piece of proximal portion, but there is a full
impression of this bone in the matrix. Thus, the length and the shape of the humerus can be restored. The distal
portion of the humerus is curved, but this may be an artefact of preservation. The remaining part of the shaft is
straight. The deltopectoral crest is located proximally and is semicircular in shape. Its ventral margin is rounded.
The ulna and radius are displaced at their proximal portions, but the impressions of their distal ends allow their
lengths can be measured. They are straight bones that extend parallel to each other. The length ratio of the ulna to
the tibia is 94.2%.
Three carpals can be identified. The proximal carpals are fused into a rectangular unit, whose ventral surface is
concave. There are two distal carpals; the lateral one that articulates with the pteroid is smaller than the medial one,
which articulates with the proximal ends of metacarpals II-IV. Most of the ventral surface of the medial distal
length width
Isolated teeth 19.3; 17.6; 10.9 2.4; 2.5; 2.1
Lower jaw 105.6 9.0 (depth)
Caudal vertebrae (1–13) 150 -
Humerus 77.2 7.5
Ulna/radius 65.1 7.6/4.7
Pteroid 15.9 2.2
Metacarpals I–IV 24.2/24.2/24.2/29.3 1.7/1.7/2.1
Wing phalanx 1/Wing phalanx 2 85.7/118.3 6.5/4.8
Femur 68.3 6.1
Tibia 69.1 5.2
Metatarsals I–V 35.2/35.3/35/27.5/? 1.7/1.0/1.0/1.6
Digits 1 and 2 of the fifth toe 25.6/24.6 1.6/0.6
Angle of digit 2 of the fifth toe 140° -
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carpal is concave. The lateral distal carpal is circular in shape. The pteroid is very short and stout (Fig. 4b). The
distal end of the pteroid is blunt, not as pointed as in pterodactyloids such as dsungaripterids (Lü et al. 2009). The
length ratio of the pteroid to the humerus is 0.21. Metacarpals I-III are essentially equal in size and length, and they
are slightly shorter than metacarpal IV. The ratio of the length of metacarpal IV to that of the humerus is 0.38. This
falls slightly out of the range of ratios seen in Rhamphorhynchinae (Unwin 2003; Hone et al. 2012: ratio range:
0.39–0.68) (Table 2).
FIGURE 3. The holotype of Orientognathus chaoyangensis gen. et sp. nov. (41HIII-0418). a, photograph; b,line drawings.
Abbreviations: cr, coracoid; crs, crushed skull; cau, caudals; dor+dorr, dorsals + dorsal ribs; f, femur; h, humerus; ja, jaw; jt,
jaw point; isc, ischium; mcl, manual claw; mtc, metacarpals; mtt, metatarsals; pt, pteroid; sft, second phalange of the fifth toe;
t, tooth; ti, tibia; u/r, ulna and radius; wph1-3, wing phalanxes 1-3.
The right hand is not well preserved, but the left hand is in better condition. The third finger is the longest
among the first three fingers, whereas the first finger is the shortest (Fig. 3). The manual unguals are large and
likely larger than those of the pes (although the pedal claws are not preserved, their small size is inferred from the
slender pedal digits), which is normal for pterosaurs. The unguals bear sharp tips and their proximal ends and are
expanded, with strong flexor tubercles. The articular surfaces with the distal digits occupy half of the width of the
proximal end of each ungual. The distal part of wing phalanx 3 and wing phalanx 4 are missing. Wing phalanx 1 is
shorter than wing phalanx 2. The proximal articular end of the first wing phalanx bears an unfused extensor tendon
process, which indicates that the specimen is not osteologically mature.
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FIGURE 4. The holotype of Orientognathus chaoyangensis gen. et sp. nov. (41HIII-0418); a, Close up of the rostral end of
the jaw; b, Close up of near the wrist (showing the pteroid); c, Whole skeleton; d, Close up of the pes (showing the fifth toe), e,
Close up of the anterior portion of the tail.
The right ilium is only partially preserved. It bears an elongated preacetabular process and there is a clear
concavity on the lateral surface that articulates with the femoral head. The postacetabular process is relatively
short. The pubis is not preserved. The ischium is well preserved; it is fan-like, with a rounded posteroventral
margin, and it bears a distinct neck. The left femur is nearly complete. It has a straight shaft, and a ball-shaped head
set off on a distinct neck. The proximal portion of the tibia is missing, but based on its position relative to the femur
and impression near the distal end of the femur, its length can be measured. It is slightly longer than the femur, with
a tibia: femur length ratio of 1.01. The distal end of the fibula is not fused to the tibia. Two small round bones near
the distal end of the tibia may be the tarsals. The pes is narrow and slender. The metatarsals are long and thin, with
metatarsal II being the longest. Metatarsal III is shorter than metatarsal I but longer than metatarsal IV. The ratio of
the length of the third metatarsal to that of the tibia is 0.51. Metatarsal V is small and perhaps missing a small
portion. The first digit of the fifth toe is straight and nearly similar to metatarsal I-IV in size and shape. The second
digit of the fifth toe is slender, long and curved, and the angle of the second digit of the fifth toe is 140° (Fig. 4d).
Phylogenetic analysis. To evaluate the systematic position of Orientognathus among non-pterodactyloid
pterosaurs, the new taxon was added to the data matrix published byet al. (2012) (Appendix 1). The dataset
consists of three taxa as outgroups (Preondactylus, Dimorphodon and Peteinosaurus) and 21 taxa as ingroups.
Parsimony analysis of the dataset was carried out using PAUP* software (version 4.0b1) (Swofford 2002) under the
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following settings: characters were treated as unordered and of equal weight (except for characters 5 and 55, which
were treated as ordered); multiple states for a single taxon were interpreted as a polymorphism; addition sequence
was set as furthest; default character state optimization was set as DELTRAN. Support for individual nodes was
estimated through a bootstrap analysis (1000 replicates) using a heuristic search and the settings listed above. The
analysis recovered 2931 most parsimonious trees (MPTs), each with a tree length of 192, consistency index (CI) of
0.6510, retention index (RI) of 0.7774, and rescaled consistency index of 0.5061. The strict consensus of these
MPTs (Fig. 5) shows that Orientognathus falls within the clade Rhamphorhynchinae and it is more derived than
Pterorhynchus. Orientognathus shares the following two unambiguous characters with Rhamphorhynchinae:
tapering, spike-like rostral process; and a pteroid that is less than 30% of the length of the humerus. The
autapomorphies of Orientognathus are (1) teeth are peg-like and widely spaced; (2) absence of a lateral pneumatic
foramen on the cervical centra; (3) deltopectoral crest of humerus that is large and subtriangular with a proximally
directed apex; (4) an ulna whose length is less than 133% of that of the humerus; (5) ulna:tibia ratio: 0.9–1.2; and
(6) pubis and ischium are unfused.
FIGURE 5. Strict consensus of the 2931 most parsimonious trees (Tree length = 192, CI = 0.6510, RI = 0.7774, RCI = 0.5061),
showing the relationship of Orientognathus chaoyangensis gen. et sp. nov. (41HIII-0418) to other basal pterosaurs.
1,
Dimorphodontidae;
2
, Anurognathidae;
3
,Campylognathoididae;
4
, Scaphognathinae;
5
, Rhamphorhynchidae;
6
,
Rhamphorhynchinae;
7
, Monofenestrata.
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Comparison and discussion
Orientognathus is assigned to the Rhamphorhynchidae based on the following characters: mandible tips fused into
a short symphysis bearing a forward-projecting prow; a number of large, fang-like, procumbent teeth forming a
fish grab (Unwin 2003); and jaws with edentulous tips (shared with Rhamphorhynchus muensteri [Wellnhofer
1975a, 1978; Bennett 1995] and Bellubrunnus rothgaengeri [Hone et al. 2012]); anterior teeth long and angled
forward and laterally; femur shorter than the humerus (shared with Rhamphorhynchus muensteri [Wellnhofer
1975a, 1978; Bennett 1995] and Qinglongopterus guoi [Lü et al. 2012]).
FIGURE 6. Jaw structure comparisons of Rhamphorhynchus muensteri, Scaphognathus (modified from Wellnhofer, 1975a)
and Orientognathus (reversed). Scale bars = 1 cm.
The ulna is shorter than the tibia in Orientognathus, similar to basal pterosaurs such as Preondactylus and
Dimorphodontidae, which exhibit a primitive condition (Unwin et al. 2000). The edentulous tip of the jaw is not as
long as in Rhamphorhynchus muensteri (Bennett 1995; Wellnhofer 1975a) and it is also not as short and deep as in
Scaphognathus (Wellnhofer 1975a) (Fig. 6). The tip morphology of Orientognathus is somewhat intermediate
between the conditions of Rhamphorhynchus and Scaphognathus, more similar to that of Dorygnathus (Padian
2008). The tooth morphology is similar to Rhamphorhynchus.
The distal end of the pteroid is expanded, similar to the condition in most basal pterosaurs, such as
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Qinglongopterus (Lü et al. 2012), Rhamphorhynchus, Dorygnathus (Padian 2008), and Campylognathoides
liasicus (Wellnhofer 1974), but different from the condition in pterodactyloid pterosaurs, where the distal end of
the pteroid is slender and pointed (e.g., Dsungaripterus: Lü et al. 2009; Darwinopterus: Lü et al. 2010a). The
length of the pteroid is 21% of the humerus length, which is similar to the ratio in Qinglongopterus (22.5%: Lü et
al. 2012). In more distantly related taxa this ratio is much greater, as it is about 40% in Campylognathoides liasicus
(Wellnhofer 1974) and 70% in Darwinopterus robustodens (Lü et al. 2011a). Like basal non-pterodactyloids such
as Preondactylus, Dimorphodontidae and Anurognathidae (Unwin et al. 2000), the metatarsals of Orientognathus
exhibit the primitive condition in being highly elongate, slender and subequal to each other in length (Table 1).
TABLE 2. Proportions of the lengths of major elements among various rhamphorhynchines (modified from Hone et al.
2012). Fenghuangopterus from Lü et al. (2010b), Scaphognathus (SMNS 59395) from Bennett (2014); Orientognathus
(41HIII-0418) from this study. Note: in the table 3 of Hone et al. (2012), the last column should refer to the metacarpal
IV/humerus ratio.
Orientognathus shares one character with Rhamphorhynchus, Eudimophodon and Campylognathoides: the
second wing phalanx is longer than the ulna, whereas in other most non-pterodactyloid pterosaurs, the ulna is
longer than wing phalanx two (Unwin et al. 2000).
Orientognathus differs from Scaphognathus in that the ulna is shorter than each wing phalanx in
Orientognathus, whereas the ulna is longer than each wing phalanx in Scaphognathus (Bennett 2014). The second
phalanx of pedal digit V is at an angle of 140° in Orientognathus, but bears an angular flexure of 40-45º at mid-
length in Scaphognathus (Bennett 2014).
Orientognathus differs from Rhamphorhynchus in the shape of the deltopectoral crest of the humerus: there is
no clear neck on the crest in Orientognathus, but a distinct neck on the tongue-shaped deltopectoral crest in
Rhamphorhynchus (Wellnhofer 1991). The length ratio of the metacarpal IV to humerus is approximately 0.38 in
Orientognathus, which is much smaller than in Rhamphorhynchus, which has a ratio of approximately 0.60
(Wellnhofer 1975b) (Table 2).
Orientognathus differs from Qinglongopterus, Pterorhynchus, Darwinopterus, Fenghuangopterus,
Jianchangopterus and Jianchangnathus, which come from the Middle to Late Jurassic deposits of western
Liaoning and surrounding areas of China.
Taxon Humeral length
mm
Humerus/Femur Ulna/Tibia Metacarpal IV /
Humerus ratio
Rhamphorhynchinae - 1.03–1.48 1.25–1.81 0.39–0.68
Rhamphorhynchus (1) TM 6924 16.5 1.32 1.72 0.60
Rhamphorhynchus (1) BSP 1889 XI.1 15.5 1.32 1.72 0.61
Rhamphorhynchus (1) MB 14.5 1.32 1.60 0.54
Rhamphorhynchus (1) MMK V45/1 13.5 1.23 1.62 0.63
Rhamphorhynchus (1) UB E 554 21.8 1.28 1.70 0.63
Rhamphorhynchus (1) 19 1.19 1.86 0.53
Rhamphorhynchus (2) MLU 33 1.18 1.56 0.58
Rhamphorhynchus (2) SMD 34 1.21 1.45 0.53
Dorygnathus BSP 1938 149 51 1.21 1.38 0.49
Dorygnathus UUPM R 157 61 1.22 1.48 0.48
Qinglongopterus D3080 17.8 1.46 1.85 0.93
Nesodactylus AMNH 2000 46.5 - - 0.57
Bellubrunnus BSP–1993–XVIII–2 14 1.40 1.83 0.64
Fenghuangopterus 63 1.11 0.85 0.56
Scaphognathus (SMNS 59395) 29 1.06 1.54 0.46
Orientognathus 77.2 1.13 0.92 0.38
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Orientognathus differs from Qinglongopterus in having a smaller ratio of the length of the metacarpal IV to
the humerus (0.38 vs. 0.51; Lü et al. 2012). The shape of the deltopectoral crest in Orientognathus is also different
from that of Qinglongopterus, where it is more developed compared with the humeral shaft.
Orientognathus differs from Pterorhynchus (Czerkas and Ji 2002) in that the anterior teeth are stouter and
longer in Orientognathus than in Pterorhynchus. The length ratio of metacarpal IV to humerus is also smaller in
Orientognathus (0.38 vs. 0.55).
Orientognathus differs from the scaphognathine pterosaur Fenghuangopterus (Lü et al. 2010b) in that the teeth
are straight in Orientognathus whilst they are curved in Fenghuangopterus. The length ratio of metacarpal IV to
humerus is smaller in Orientognathus, which also has a shorter length ratio of the metacarpals to humerus (0.38 vs.
0.56). The rostral end of the lower jaw is toothless and pointed in Orientognathus, but expanded in
Fenghuangopterus.
It is difficult to compare Orientognathus with Jianchangnathus (Cheng et al. 2012), because of the lack of
overlapping complete elements. The teeth of Jianchangnathus are relatively smaller and stouter than these of
Orientognathus.
Orientognathus differs from Jianchangopterus (Lü and Bo 2011c) in that the tibia is much longer than the
femur in Jianchangopterus, whilst the length of tibia is nearly equal to the femur in Orientognathus. The length
ratio of the pteroid to the humerus is smaller in Orientognathus (approximately 0.21) than in Jianchangopterus
(approximately 0.42), and the length ratio of metacarpal IV to the humerus is approximately 0.38 in
Orientognathus but much larger in Jianchangopterus (approximately 0.82).
Orientognathus differs from the transitional form Darwinopterus in that the length ratio of the pteroid to the
humerus is smaller in Orientognathus (0.21 vs. 0.59). Furthermore, the pteroid is short with an expanded distal end
in Orientognathus, but it is slender with a pointed distal end in Darwinopterus (Lü et al. 2009; Wang et al. 2010).
The length ratio of the metacarpal IV to the humerus is approximately 0.66 in Darwinopterus, which is much larger
than in Orientognathus (approximately 0.38).
Orientognathus most likely comes from the Late Jurassic Tuchengzi Formation, which is younger than the
Tiaojishan Formation (Bureau of Geology and Mineral Resources of Liaoning Province 1989). It therefore most
likely represents the youngest Jurassic pterosaur found in China thus far.
Conclusions
Orientognathus is the largest rhamphorhynchinae pterosaur discovered in the Upper Jurassic deposits of
northeastern China thus far. The discovery of Orientognathus may help fill the temporal gap between the better-
sampled Middle Jurassic and Early Cretaceous pterosaur faunas of China, and indicates that more Upper Jurassic
pterosaurs may remain to be found.
Acknowledgements
The authors are indebted to Dr. Dave Hone and an anonymous reviewer, who reviewed the first draft of the
manuscript and made constructive suggestions. This research was supported by grants from the National Natural
Science Foundation of China (grant no. 41272022) and the China Geological Survey (grant no. 12120114026801)
to Lü JC. The specimen was prepared by Y. Q. Zhang (CAGS).
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APPENDIX 1. Character codings for Orientognathus chaoyangensis gen. et sp. nov. for the phylogenetic analysis of Lü
et al. (2012). The complete matrix includes 82 characters and 24 taxa (with Orientognathus chaoyangensis gen. et sp.
nov. added).
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