Sexually Dimorphic Tridimensionally Preserved Pterosaurs and Their Eggs from China

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Current Biology 24, 1323–1330, June 16, 2014 ª2014 Elsevier Ltd All rights reserved http://dx.doi.org/10.1016/j.cub.2014.04.054 Article Sexually Dimorphic Tridimensionally Preserved Pterosaurs and Their Eggs from China

Xiaolin Wang,1,* Alexander W.A. Kellner,2,* paralleled in any living reptile [1]. Being volant animals with Shunxing Jiang,1,3 Qiang Wang,1 Yingxia Ma,4 fragile skeletons, most known pterosaur species are repre- Yahefujiang Paidoula,4 Xin Cheng,1,3 Taissa Rodrigues,5 sented by only one or two specimens at best, with little infor- Xi Meng,1 Jialiang Zhang,1,3 Ning Li,1,3 and Zhonghe Zhou1 mation available regarding their populations [2–4]. Pterosaur 1Key Laboratory of Vertebrate Evolution and Human Origins, eggs are even rarer, with only four isolated and flattened spec- Institute of Vertebrate Paleontology and Paleoanthropology, imens found to date [5–8]. Fieldwork carried out since 2006 in Chinese Academy of Sciences, PO Box 643, Beijing 100044, the Turpan-Hami Basin, south of the Tian Shan Mountains in China Xinjiang, northwestern China, has revealed a new pterosaur- 2Laboratory of Systematics and Taphonomy of Fossil rich area with potentially thousands of bones, including tridi- Vertebrates, Department of Geology and Paleontology, Museu mensionally preserved male and female skulls and eggs Nacional/Universidade Federal do Rio de Janeiro, Quinta da discovered together for the first time. Hundreds had already Boa Vista s/n, Sa˜ o Cristo´ va˜ o, CEP 20940-040, Rio de Janeiro, been collected in a small area, all from part of the Lower Creta- RJ, Brazil ceous Tugulu Group [9, 10], which was formed under fluviola- 3University of Chinese Academy of Sciences, Beijing 100049, custrine conditions. In the sedimentary sequence, there are China some tempestite interlayers, in which the gray-white sand- 4Hami Museum, Hami 839000, China stones and brown mudstone breccias that were deposited at 5Department of Biology, Agrarian Sciences Center, different depths of the lake are mixed together. Tempestite in- Universidade Federal do Espı´rito Santo, Alto Universita´ rio s/n, terlayers where nearly all of the pterosaur fossils are found Caixa Postal 16, Guararema, CEP 29500-000, Alegre, ES, Brazil suggest that large storms caused the mass mortality, event deposits, and lagersta¨ tte of the pterosaur population. Overall, the pterosaurs are well preserved, with the white- Summary colored bones showing little distortion (Figures 1 and 2). About 40 individuals (wingspan 1.5–3.5 m) were recovered, but the Background: The pterosaur record is generally poor, with little actual number might be in the hundreds. These specimens information about their populations, and pterosaur eggs are provide new and important evidence regarding male and even rarer, with only four isolated and flattened eggs found female morphologies, reproduction, ontogeny, and eggshell to date. microstructure. Results: We report here a population of a new sexually dimorphic pterosaur species (Hamipterus tianshanensis gen. et sp. Results and Discussion nov.), with five exceptionally well-preserved three-dimensional eggs, from the Early Cretaceous deposit in northwestern China. Systematic Paleontology About 40 male and female individuals in total were recovered, Pterosauria Kaup, 1834. but the actual number associated might be in the hundreds. Pterodactyloidea Plieninger, 1901. All of the discovered skulls have crests, which exhibit two dif- Pteranodontoidea Marsh, 1876 sensu Kellner (2003) [11]. ferent morphologies in size, shape, and robustness. The eggs Hamipterus tianshanensis gen. et sp. nov. show pliable depressions with cracking and crazing on the outer Etymology surface. The eggshell, observed by scanning electron micro- Hamipterus tianshanensis; from ‘‘Hami,’’ referring to the region scopy and energy-dispersive spectroscopy, comprises a thin where the specimens were found; ‘‘pteros,’’ Greek, meaning calcareous external hard shell followed by a soft membrane. ‘‘wing’’; and ‘‘tianshanensis,’’ referring to the Tian Shan Moun- Conclusions: These fossils shed new light on the reproductive tains in Xinjiang. This region was added to the UNESCO World strategy, ontogeny, and behavior of pterosaurs. The cranial Heritage List in 2013. crests show sexually dimorphic morphologies, with presumed Holotype males and females differing in crest size, shape, and robust- One complete presumed female skull (IVPP V18931.1) housed ness. Ontogenetic variation is reflected mainly in the expan- at the Institute of Vertebrate Paleontology and Paleoanthro- sion of the rostrum. The eggs have some external rigidity of pology (IVPP), Chinese Academy of Sciences, Beijing, China the general pliable eggshell, and the microstructure of the (Figures 1, 3A, and 3C; see also Table S1 available online). eggshell is similar to that of some modern ‘‘soft’’ snake eggs. Paratypes We suggest that this new pterosaur nested in colonies and One nearly complete presumed male skull (IVPP V18935.1) thus exhibited gregarious behavior, a possible general trend housed at the IVPP (Figures 3B and 4B; see also Table S1). for at least derived pterodactyloid pterosaurs. Referred Specimens Several cranial and postcranial elements (IVPP V18931– Introduction V18941) (Figures 1, 2, 3, 4, 5, 6, and S1–S6; Table S1–S3). Locality and Horizon Pterosaurs are extinct flying reptiles that achieved powered Hami, Xinjiang, China; Lower Cretaceous Tugulu Group [9, 10]. flight, developing an entirely distinctive anatomy that is not Diagnosis Pteranodontoid pterodactyloid pterosaur exhibiting the fol- *Correspondence: [email protected] (X.W.), [email protected] lowing autapomorphies: hook-shaped bony process on the (A.W.A.K.) tip of the dentary; lacrimal process of jugal thin, anteriorly Current Biology Vol 24 No 12 1324

Figure 1. Photo and Line Drawing of Hamipterus tianshanensis gen. et sp. nov. IVPP V18931 in a Large Block (A) Photo. (B) Line drawing. This block preserves three skulls, including a complete female skull (holotype, IVPP V18931.1), an incomplete female skull (IVPP V18931.2), and an incomplete male skull (IVPP V18931.3), the major part of the largest articulated forelimb found thus far, and many other postcranial elements. Scale bar, 10 cm. at- ax, atlas-axis; car, carpus; cv, cervical vertebra; dca, distal carpal; dlca, distal lateral carpal; dv, dorsal vertebra; mcIV, metacarpal IV; pel, pelvis; ph1d4, ﬁrst wing phalanx; prca, proximal carpal; ptd, pteroid; ra, radius; ri, rib; sca-cor, scapulocoracoid; sk, skull; st, sternum; ul, ulna; r, right; l, left. See additional block in Figure S1. directed, and dorsally expanded; well-developed crest on following combination of characters: premaxillary crest with supraoccipital; ventral pneumatic foramen close to the base developed anteriorly curved ridges and sulci; developed of the deltopectoral crest; distal lateral carpal with ventrally palatal ridge extending to the anterior tip of the premaxilla; directed spike-like process. The new species can be further developed dentary groove reaching the tip of the dentary; distinguished from other pteranodontoid pterosaurs by the anterior tip of the premaxilla and dentary laterally slightly Sexually Dimorphic Pterosaurs with Eggs from China 1325

Figure 2. Hamipterus tianshanensis gen. et sp. nov. with Abundant Bones and Tridimensional Eggs (A) A block (IVPP V18933) with an incomplete female skull (IVPP V18933.1), a weathered egg (IVPP V18933.2) that may belong to that female, a row of teeth, six humeri (four left and two right, indicating at least four individuals), and many other postcranial elements. Scale bar, 5 cm. (B) Opposite side of two humeri in the frame in (A). Scale bar, 2 cm. (C) A block (IVPP V18932) with an incomplete skull (IVPP V18932.1) closely associated with an egg (IVPP V18932.2) and a right humerus. The skull is interpreted as belonging to a male due to the large and robust cranial crest, starting above the ﬁfth tooth position. The crest shows developed anteriorly curved ridges and sulci and an arc-shaped anterior margin. Scale bar, 10 cm. (D) Close-up of the deformed egg. Scale bar, 1 cm. car, carpus; cv, cervical vertebra; dca, distal carpal; dv, dorsal vertebra; eg, egg; fo, foramen; gas, gastralia; hu, humerus; mt, metatarsal; nf, nutrient foramen; obfo, obturator foramen; pel, pelvis; phd4, indeterminate wing phalanx; prca, proximal carpal; scp, supracondylar process; sk, skull; te, teeth; r, right; l, left; ?, uncertain. See additional diagnosis in Figure S5.

surface and a strongly curved anterior margin, starting before the sixth alveolus, and the other smaller, less rugose, and placed further backward, starting beyond the sixth alveolus. Although morphological variation could be interpreted as individual variation, these marked differences suggest that the skulls belong to different genders (Fig- ures 3 and S2). We have interpreted the specimens with larger crests as males and those with smaller crests as females ([14]; see Discussion). A similar number of lower jaws were recovered, seven of which were expanded; moderately warped deltopectoral crest (Figures 1, complete. These are laterally expanded as in anhanguerids 2, 3, 4, S1–S3, and S5). [12, 15], with the largest expansion occurring around the third alveolus, becoming more pronounced in larger in- Description and Comparison dividuals (width 11.3–20.6 mm). The mandibular symphy- Hamipterus has a laterally expanded premaxilla, similar to that sis has a hooked medial process and occupies between of anhanguerids [12], giving it a spoon-shaped appearance. 41% and 46% of the mandibular length (Figures 4 and S3; The largest expansion is found between the third and fourth Table S2). alveoli and varies from 9.6 to 32.5 mm in width, becoming On each side, there are 19 teeth in the upper jaw (13–14 ante- more pronounced in larger individuals. The most constricted rior to the nasoantorbital fenestra) (Figures 3 and 4) and 15 in area is between the sixth and seventh alveoli. A palatal ridge the lower jaw (10–11 on the symphysis) (Figures 4 and S3). starts at the tip, ending close to the anterior margin of the These are laterally ﬂattened, with smooth labial but ﬂuted choanae (Figure 4). lingual enamel surfaces, similar to the condition reported for The premaxillary crest, present in all recovered specimens, some Anhangueria [12, 16]. The teeth vary in size, position, starts between the premaxillary tip and the anterior margin of and morphology, from large, anterolaterally inclined, and the nasoantorbital fenestra, extending above the occipital re- lance-shaped to smaller, vertical, and more posteriorly trian- gion as in Dsungaripterus [13]. The anterior surface is rather gular. All are curved medially, and their main axis is at an angle thick and rugose, becoming thinner and smoother posteriorly. with the lateral margin of the jaw. The pterygoid completely The dorsal margin is straight, with a rugose upper part sug- divides the subtemporal opening, forming a secondary sub- gesting a soft tissue extension. Two skulls of about the same temporal fenestra, which is also present in tapejarids but size show different crests, one larger with a more rugose unknown in other pteranodontoids [15, 17]. Current Biology Vol 24 No 12 1326

Figure 3. Male and Female Skulls of Hamipterus tianshanensis gen. et sp. nov. (A) IVPP V18931.1, holotype. (B) IVPP V18935.1, paratype. (C) Outline of holotype showing female crest; gray part with white lines shows male crest. (D) IVPP V18932.1. (E) IVPP V18931.2. (F) IVPP V18931.3. (A) and (E) are females; (B), (D), and (F) are males. Male skulls have larger and thicker crests than female skulls; male crests also have more strongly curved anterior margins than female crests and are positioned more anteriorly. f, frontal; fola, foramen lacrimale; j, jugal; la, lacrimal; ltf, lower temporal fenestra; m, maxilla; naof, nasoantorbital fenestra; or, orbit; p, parietal; pm, premaxilla; pmcr, premaxillary crest; po, postorbital; pplf, postpalatinal fenestra; q, quad- rate; so, supraoccipital; sq, squamosal; sstf, secondary subtemporal fenestra; stf, subtemporal fenestra; te, teeth; utf, upper temporal fenestra. Scale bars, 5 cm. See Figure S2 for additional skulls with crests; see Table S1 for measurements of the skulls.

Regarding the postcranial skeleton, almost every part of Discussion the skeleton is represented (Figures 1, 2, S4, and S5). The cervical vertebrae are rectangular and bear a lateral pneu- Several features indicate that Hamipterus is a member of the matic foramen. The scapula is shorter than the coracoid. derived pterodactyloid clade Pteranodontoidea (warped del- The coracoid shows a small biceps tubercle similar to the topectoral crest, triangular-shaped distal syncarpal, spike- condition reported in the Anhangueridae [15]. The humerus like neural spine of cervical vertebrae, coracoid larger than shows a developed deltopectoral crest that is warped, the scapula [11, 17]). Within that group, it differs from Pteran- similar to Pteranodon, but less as compared to Anhanguera odon and related taxa [17, 19] in having teeth, a stout scapula and Istiodactylus (e.g., [11, 18–20]). The humerus also shows with a constricted shaft, and a radius of diameter less than half a developed pneumatic foramen on the ventral surface that of the ulna. Hamipterus differs from the Istiodactylidae in close to the base of the deltopectoral crest that differs from its dentition, rostral margin, and skull openings [20]. Finally, it the one situated closer to the proximal margin, observed in is also not a member of the Anhangueridae due to its distinct other pteranodontoids [15, 17]. In larger individuals, the premaxillary crest and lack of a dentary crest, among other dif- proximal and distal carpal series are fused. The distal articu- ferences [11, 21](Figures 1, 2, 3, 7, S2, and S3). lation is D-shaped, contrary to other pteranodontoids. The So far, Hamipterus is the ﬁrst pterosaur recorded from the distal syncarpal has a triangular shape. The distal lateral Turpan-Hami Basin. The Junggar Basin, located north of the carpal shows a unique ventrally directed spike-like process. Tian Shan Mountains, has yielded a long-tailed pterosaur The sacrum is composed of six fused sacral vertebrae. Pubis from the Late Jurassic, Sericipterus [22], and three genera and ilium are fused, forming a continuous ventral plate. The from the Early Cretaceous, Dsungaripterus, Noripterus, and femur has a long, thin shaft and is rather straight, not bowed. Lonchognathosaurus, regarded as part of the Dsungaripteri- The ﬁbula is splint-like and very reduced, not reaching the dae and the Wuerho pterosaur fauna [13, 23, 24]. Hamipterus tarsus. differs from dsungaripterids in its dentition, rostrum, cranial Sexually Dimorphic Pterosaurs with Eggs from China 1327

Figure 4. Upper and Lower Jaws of Hamipterus tianshanensis gen. et sp. nov. (A–C) Upper jaws. (D–F) Lower jaws. (A) IVPP V18935.2. (B) IVPP V18935.1. (C) IVPP V18935.3. (D) IVPP V18936.4. (E) IVPP V18936.2. (F) IVPP V18936.1. Jaws show the developed palatal ridge that extends to the anterior tip of the premaxilla and the developed dentary groove reaching the tip of the dentary. The anterior tip of the premaxilla and dentary is laterally expanded, and the expansion becomes progressively wider during ontogeny. Scale bar, 5 cm. See Figures S3 and S4 for additional related bones; see Table S2 for measurements of lower jaws. openings, and postcranial features such as a warped delto- versus absence, might be a means of distinguishing gender pectoral crest and a straight femur (Figure 2). in pterosaurs (Figures 3 and S2). The main ontogenetic changes observable in Hamipterus are the expansion of the rostral end and the premaxillary crest, Eggs both of which become progressively more robust (Figure 4). Besides the bones, a total of five eggs were recovered from the The distal end of the rostrum of the upper jaw also becomes same site (Figures 2, 5, 6, and S6; Table S3). All show three- more expanded laterally in the archaeopterodactyloid Cteno- dimensional preservation and are elongated and slightly chasma elegans [25], although not to the same degree as in asymmetrical; most are 59–65 3 34 mm in size (w40–50 g Hamipterus. Furthermore, in larger individuals of the new spe- [8]) (Table S3). One egg is comparatively small (29.6 3 cies, the cranial crest starts at the fifth alveolus instead of the 22.8 mm; w14 g [8]) and likely not fully developed, although sixth, and ridges and grooves become more apparent. The egg size variation within a given species is common [31, 32]. rostral end is deflected dorsally in smaller individuals but is The outer surface is smooth and exhibits no ‘‘papilla-like orna- straight in larger ones, and the dentary fossa is more elongated mentation,’’ as was reported of the first pterosaur egg found in and deeper in larger individuals as well. The number of teeth China [5]. All show depressions of differing degrees that did and the proportional sizes of the mandibular symphysis not cause rupture of the shell as would be typical for hard- remain constant. Regarding postcranial elements, no main shelled eggs. Nevertheless, despite the shell being pliable, anatomical differences are noticeable due to a lack of articu- the depressed areas show cracking and crazing, indicating lated skeletons representing different ontogenetic stages, that the outer surface had some rigidity (Figure 5A). Energy- and histological sections are planned (Figure S4). dispersive spectroscopy (EDS) performed under scanning Determining the gender of the distinct morphs is not an easy electron microscopy (SEM) showed the presence of an task. In several extant reptile species today, the female tends w60 mm thin calcareous eggshell layer, followed by a thin to be larger, but overall, in most extant lizards, crocodilians, (w11 mm) shell membrane (Figure 5, 6, and S7; Table S4). and birds showing sexual dimorphism, the reverse is true Due to the close proximity to Hamipterus tianshanensis, the [26]. Within pterosaurs, sexually dimorphism has been re- sole taxon found at the site, all of the eggs are referred to this ported for Pteranodon, where two distinct species show males species. The ‘‘soft’’ eggs of modern reptiles comprise a thin and females presenting crests, with the one in the supposed calcareous hard layer or isolated calcareous grains followed female smaller [14]. Although some controversy about the by a thick soft membrane [33]. Compared with other reptiles, diversity of the Pteranodon material has recently been raised however, the Hamipterus eggs show more similarities with with the recognition of two more genera, bringing the total some squamates, including colubrid snakes such as Elaphe number of species to four [19], sexual dimorphism cannot be [33]. SEM analysis of a similarly sized (53.5 3 29.7 mm) Elaphe entirely ruled out for at least part of the specimens attributed egg (Figure 5) also shows a thin calcareous layer (60–70 mm) to this genus [17], in which case our study corroborates the followed by a much thicker membrane (w200 mm) and the interpretation that females had smaller cranial crests than same pliable condition. It is possible that Hamipterus also males. had a much thicker membrane, which was not completely pre- Recently, there has been a suggestion that in the nonptero- served. We propose that such an eggshell structure, similar to dactyloid clade Wukongopteridae, the presence versus that of some snakes, may well explain the preservation of the absence of cranial crests is a sexually dimorphic character outer surface observed in pterosaur eggs. extensive to other pterosaurs [8], despite the fact that crest- Only four pterosaur eggs have been previously reported, less members of that clade have been reported [27]. Even three from China, and all highly compressed. Two were acknowledging the distinct variation in sexual dimorphism discovered in the Lower Cretaceous Yixian Formation, and (e.g., [28–30]), it is important to note that Hamipterus tiansha- despite that they contain embryos, controversy remains about nensis contradicts this hypothesis, because this species indi- their taxonomic affiliation [5, 6, 34, 35]. A third egg was found in cates that morphology of the crest, rather than its presence direct proximity to a purported specimen of Darwinopterus [8], Current Biology Vol 24 No 12 1328

Figure 5. Comparison of Eggs of Hamipterus tianshanensis gen. et sp. nov. and the Colubrid Snake Elaphe (A) An egg of Hamipterus (IVPP V18937) and an egg of Elaphe. Both have similar size and pliable depressions; cracking and crazing is seen only in the pterosaur egg. Scale bar, 2 cm. (B and C) Outer surface (SEM) of an egg of Hamipterus (IVPP V18939) (B; scale bar, 50 mm) and an egg of Elaphe (C; scale bar, 100 mm). (D and E) Radial section (SEM) of an egg of Hamipterus (IVPP V18939) (D; scale bar, 50 mm) and an egg of Elaphe (E; scale bar, 200 mm). Both have a thin calcareous layer of similar thickness, followed by a membrane, which in Elaphe is much thicker than that in the preserved pterosaur egg, but it is possible that the pterosaur egg membrane in vivo may have had a thickness similar to that of the snake egg. (F) Close-up of the frame in (D). Scale bar, 5 mm. (G) Close-up of the frame in (E). The vesicles in the calcareous layers are different. Scale bar, 10 mm. See Figure S6 for the smallest Hamipterus egg; see Table S3 for measurements of the eggs.

the eggshell structure found in Hamipte- rus as a general trend for pterosaurs. The eggs are not part of the same clutch and were likely laid by different females, since they were found apart from each other, mixed with bones and subjected to limited transportation. The size variation observed also favors this interpretation, although reptile eggs in the same clutch can vary, as reported in snakes [32]. The size differences might also reflect different stages of development, since mass and dimen- sions differ between recently laid eggs and more developed ones [31]. The combination of many pterosaurs and eggs indicates the presence of a nesting site nearby and suggests that this species developed gregarious a member of the peculiar nonpterodactyloid clade Wukongop- behavior. Hamipterus likely made its nesting grounds on the teridae [36]. Of these, the only one showing an external shores of freshwater lakes or rivers and buried its eggs in eggshell ornamentation was the first [5], suggesting that it sand along the shore, preventing them from being desiccated. had an external calcareous layer. However, subsequent Further questions regarding matters such as colonial nesting, studies considered this and the other eggs recovered from fidelity to nesting grounds, and clutch and parental care China as being soft-shelled [6, 8, 34, 35]. The fourth reported remain open, but sites like the one reported here provide egg comes from the monospecific Pterodaustro beds of the further evidence regarding the behavior and biology of this Lower Cretaceous Lagarcito Formation in Argentina [7]. This amazing group of flying reptiles that has no parallel in modern egg’s preservation differs from that of the others by showing time. fragmentary pieces of a thin (30 mm) calcareous hard eggshell above an embryo [34], casting some doubts as to whether the Experimental Procedures shell was continuous or patchy [35]. Compared with those specimens, the Hamipterus eggs Materials differ in that they are tridimensional, with a calcareous hard Approximately 40 individual new specimens of Hamipterus housed at IVPP eggshell followed by a soft membrane, similar to some snakes were studied, including three-dimensionally preserved cranial and postcranial elements and five eggs. and lizards [33], which might also be the case for Pterodaustro eggs (pending the discovery of a complete specimen). Calcite Phylogenetic Analysis of Pterosaurs crystals with vesicles are also found in Hamipterus eggs, but Phylogeny was analyzed with PAUP* v4.0b10 for Microsoft Windows [37] no V-shaped calcium carbonate units or other similarities to using TBR heuristic searches and maximum parsimony. Characters were crocodylomorph eggs [34](Figure 5). In any case, we regard given equal weight and treated unordered (ACCTRAN setting). The data Sexually Dimorphic Pterosaurs with Eggs from China 1329

Figure 6. Hamipterus tianshanensis gen. et sp. nov. Egg, IVPP V18939, Used in SEM and EDS (A and B) The complete egg before the SEM and EDS analyses; the white line in (B) indicates the position of the cut. (C) Radial section of the egg. (D) Counterpart of the radial section in (C), used in SEM. Black arrows in (C) indicate the pliable eggshell in matrix; white arrows in (A) and (C) indicate breccia detritus in the tempestite; frame in (D) indicates the position observed in SEM. Scale bar, 1 cm. See Figure S7 and Table S4 for EDS results. matrix was based on a previous study [16]. The coding of Hamipterus tian- scanning electron microscope, and EDS analysis was performed with an shanensis is 002010100030001111001011100?0101012?11012101020121 Oxford Instruments INCA x-act. 1000–00000001?110101???1111??002???01410222212?????????. Supplemental Information SEM and EDS Analysis Eggs of Hamipterus and Elaphe were cut longitudinally and gilded with car- Supplemental Information includes seven ﬁgures and four tables and can be bon (increasing the carbon percentage without affecting the conclusions in found with this article online at http://dx.doi.org/10.1016/j.cub.2014.04.054. our analysis). The samples were then observed with a Hitachi S-3700N Author Contributions

X.W. and A.W.A.K. designed the project and wrote the manuscript. X.W., S.J., X.M., and Y.M. carried out ﬁeld work and collected the specimens. Q.W., S.J., and N.L. performed the SEM and EDS of the eggs. All authors contributed to the manuscript and research.

Acknowledgments

We thank Z.-X. Qiu and B.-Y. Wang for their discovery of the specimens; Y. Li, L. Xiang, H.-Q. Shou, Q.-G. Liu, W. Gao, and X.-Z. Liu (IVPP) and H.-M. Wu, G.-L. Wu, H.-Y. Chen, F. Yan, Y.-L. Tian, X. Chen, Z.-J. Yin, H.-P. Dai, and J. Tong (Hami) for assistance with field work; L. Xiang, Y.-F. Guo, R.-J. Wang, H. Wang, and H.-X. Li for preparation of specimens; W. Gao for photos; and W.-D. Zhang for assistance with SEM and EDS. We also thank L. Codorniu´ (Universidad Nacional de San Luis, Argentina), G. Dyke (University of Southampton), S.C. Bennett (Fort Hays State Univer- sity), and two anonymous reviewers for several suggestions that were incor- porated in earlier versions of this manuscript. This study was supported by the National Science Fund for Distinguished Young Scholars (40825005), the National Key Basic Research Program of China (2012CB821900), the Hundred Talents Project of CAS, and the Excavation Funding and Emphatic Deployed Project of IVPP, CAS. T.R. received funding from the Fundaça˜ ode Amparo a` Pesquisa do Espı´rito Santo (FAPES 52986870/2011), and Figure 7. Strict Consensus Tree of Pterosaur Phylogeny, Using 324 Equally A.W.A.K. acknowledges founding from the Fundaça˜ o Carlos Chagas Filho Parsimonious Trees with a Length of 217 Steps de Amparo a` Pesquisa do Rio de Janeiro (FAPERJ E-26/102.737/2012) Hamipterus tianshanensis gen. et sp. nov. is in the monophyletic group and the Conselho Nacional de Desenvolvimento Cientı´fico e Tecnolo´ gico Pteranodontoidea. Data are based on a previous study [16]. (CNPq 307276/2009-9). Current Biology Vol 24 No 12 1330

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