Article. Sexually Dimorphic Tridimensionally Preserved Pterosaurs and Their Eggs from China

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1 Current Biology 24, , June 16, 2014 ª2014 Elsevier Ltd All rights reserved Sexually Dimorphic Tridimensionally Preserved Pterosaurs and Their Eggs from China Article Xiaolin Wang, 1, * Alexander W.A. Kellner, 2, * Shunxing Jiang, 1,3 Qiang Wang, 1 Yingxia Ma, 4 Yahefujiang Paidoula, 4 Xin Cheng, 1,3 Taissa Rodrigues, 5 Xi Meng, 1 Jialiang Zhang, 1,3 Ning Li, 1,3 and Zhonghe Zhou 1 1 Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, PO Box 643, Beijing , China 2 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, São Cristóvão, CEP , Rio de Janeiro, RJ, Brazil 3 University of Chinese Academy of Sciences, Beijing , China 4 Hami Museum, Hami , China 5 Department of Biology, Agrarian Sciences Center, Universidade Federal do Espírito Santo, Alto Universitário s/n, Caixa Postal 16, Guararema, CEP , Alegre, ES, Brazil Summary Background: The pterosaur record is generally poor, with little information about their populations, and pterosaur eggs are even rarer, with only four isolated and flattened eggs found to date. Results: We report here a population of a new sexually dimorphic pterosaur species (Hamipterus tianshanensis gen. et sp. nov.), with five exceptionally well-preserved three-dimensional eggs, from the Early Cretaceous deposit in northwestern China. About 40 male and female individuals in total were recovered, but the actual number associated might be in the hundreds. All of the discovered skulls have crests, which exhibit two different morphologies in size, shape, and robustness. The eggs show pliable depressions with cracking and crazing on the outer surface. The eggshell, observed by scanning electron microscopy and energy-dispersive spectroscopy, comprises a thin calcareous external hard shell followed by a soft membrane. Conclusions: These fossils shed new light on the reproductive strategy, ontogeny, and behavior of pterosaurs. The cranial crests show sexually dimorphic morphologies, with presumed males and females differing in crest size, shape, and robustness. Ontogenetic variation is reflected mainly in the expansion of the rostrum. The eggs have some external rigidity of the general pliable eggshell, and the microstructure of the eggshell is similar to that of some modern soft snake eggs. We suggest that this new pterosaur nested in colonies and thus exhibited gregarious behavior, a possible general trend for at least derived pterodactyloid pterosaurs. Introduction Pterosaurs are extinct flying reptiles that achieved powered flight, developing an entirely distinctive anatomy that is not *Correspondence: wangxiaolin@ivpp.ac.cn (X.W.), kellner@mn.ufrj.br (A.W.A.K.) paralleled in any living reptile [1]. Being volant animals with fragile skeletons, most known pterosaur species are represented by only one or two specimens at best, with little information available regarding their populations [2 4]. Pterosaur eggs are even rarer, with only four isolated and flattened specimens found to date [5 8]. Fieldwork carried out since 2006 in the Turpan-Hami Basin, south of the Tian Shan Mountains in Xinjiang, northwestern China, has revealed a new pterosaurrich area with potentially thousands of bones, including tridimensionally preserved male and female skulls and eggs discovered together for the first time. Hundreds had already been collected in a small area, all from part of the Lower Cretaceous Tugulu Group [9, 10], which was formed under fluviolacustrine conditions. In the sedimentary sequence, there are some tempestite interlayers, in which the gray-white sandstones and brown mudstone breccias that were deposited at different depths of the lake are mixed together. Tempestite interlayers where nearly all of the pterosaur fossils are found suggest that large storms caused the mass mortality, event deposits, and lagerstätte of the pterosaur population. Overall, the pterosaurs are well preserved, with the whitecolored bones showing little distortion (Figures 1 and 2). About 40 individuals (wingspan m) were recovered, but the actual number might be in the hundreds. These specimens provide new and important evidence regarding male and female morphologies, reproduction, ontogeny, and eggshell microstructure. Results and Discussion Systematic Paleontology Pterosauria Kaup, Pterodactyloidea Plieninger, Pteranodontoidea Marsh, 1876 sensu Kellner (2003) [11]. Hamipterus tianshanensis gen. et sp. nov. Etymology Hamipterus tianshanensis; from Hami, referring to the region where the specimens were found; pteros, Greek, meaning wing ; and tianshanensis, referring to the Tian Shan Mountains in Xinjiang. This region was added to the UNESCO World Heritage List in Holotype One complete presumed female skull (IVPP V ) housed at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, Beijing, China (Figures 1, 3A, and 3C; see also Table S1 available online). Paratypes One nearly complete presumed male skull (IVPP V ) housed at the IVPP (Figures 3B and 4B; see also Table S1). Referred Specimens Several cranial and postcranial elements (IVPP V18931 V18941) (Figures 1, 2, 3, 4, 5, 6, and S1 S6; Table S1 S3). Locality and Horizon Hami, Xinjiang, China; Lower Cretaceous Tugulu Group [9, 10]. Diagnosis Pteranodontoid pterodactyloid pterosaur exhibiting the following autapomorphies: hook-shaped bony process on the tip of the dentary; lacrimal process of jugal thin, anteriorly

2 Current Biology Vol 24 No 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 V ), an incomplete female skull (IVPP V ), and an incomplete male skull (IVPP V ), the major part of the largest articulated forelimb found thus far, and many other postcranial elements. Scale bar, 10 cm. atax, 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 supraoccipital; ventral pneumatic foramen close to the base of the deltopectoral crest; distal lateral carpal with ventrally directed spike-like process. The new species can be further distinguished from other pteranodontoid pterosaurs by the following combination of characters: premaxillary crest with developed anteriorly curved ridges and sulci; developed palatal ridge extending to the anterior tip of the premaxilla; developed dentary groove reaching the tip of the dentary; anterior tip of the premaxilla and dentary laterally slightly

3 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 V ), a weathered egg (IVPP V ) 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 V ) closely associated with an egg (IVPP V ) 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. expanded; moderately warped deltopectoral crest (Figures 1, 2, 3, 4, S1 S3, and S5). Description and Comparison Hamipterus has a laterally expanded premaxilla, similar to that of anhanguerids [12], giving it a spoon-shaped appearance. The largest expansion is found between the third and fourth alveoli and varies from 9.6 to 32.5 mm in width, becoming more pronounced in larger individuals. The most constricted area is between the sixth and seventh alveoli. A palatal ridge starts at the tip, ending close to the anterior margin of the choanae (Figure 4). The premaxillary crest, present in all recovered specimens, starts between the premaxillary tip and the anterior margin of the nasoantorbital fenestra, extending above the occipital region as in Dsungaripterus [13]. The anterior surface is rather thick and rugose, becoming thinner and smoother posteriorly. The dorsal margin is straight, with a rugose upper part suggesting a soft tissue extension. Two skulls of about the same size show different crests, one larger with a more rugose 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 (Figures 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 complete. These are laterally expanded as in anhanguerids [12, 15], with the largest expansion occurring around the third alveolus, becoming more pronounced in larger individuals (width mm). The mandibular symphysis has a hooked medial process and occupies between 41% and 46% of the mandibular length (Figures 4 and S3; Table S2). On each side, there are 19 teeth in the upper jaw (13 14 anterior to the nasoantorbital fenestra) (Figures 3 and 4) and 15 in the lower jaw (10 11 on the symphysis) (Figures 4 and S3). These are laterally flattened, with smooth labial but fluted lingual enamel surfaces, similar to the condition reported for some Anhangueria [12, 16]. The teeth vary in size, position, and morphology, from large, anterolaterally inclined, and lance-shaped to smaller, vertical, and more posteriorly triangular. All are curved medially, and their main axis is at an angle with the lateral margin of the jaw. The pterygoid completely divides the subtemporal opening, forming a secondary subtemporal fenestra, which is also present in tapejarids but unknown in other pteranodontoids [15, 17].

4 Current Biology Vol 24 No Figure 3. Male and Female Skulls of Hamipterus tianshanensis gen. et sp. nov. (A) IVPP V , holotype. (B) IVPP V , paratype. (C) Outline of holotype showing female crest; gray part with white lines shows male crest. (D) IVPP V (E) IVPP V (F) IVPP V (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, quadrate; 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 the skeleton is represented (Figures 1, 2, S4, and S5). The cervical vertebrae are rectangular and bear a lateral pneumatic foramen. The scapula is shorter than the coracoid. The coracoid shows a small biceps tubercle similar to the condition reported in the Anhangueridae [15]. The humerus shows a developed deltopectoral crest that is warped, similar to Pteranodon, but less as compared to Anhanguera and Istiodactylus (e.g., [11, 18 20]). The humerus also shows a developed pneumatic foramen on the ventral surface close to the base of the deltopectoral crest that differs from the one situated closer to the proximal margin, observed in other pteranodontoids [15, 17]. In larger individuals, the proximal and distal carpal series are fused. The distal articulation is D-shaped, contrary to other pteranodontoids. The distal syncarpal has a triangular shape. The distal lateral carpal shows a unique ventrally directed spike-like process. The sacrum is composed of six fused sacral vertebrae. Pubis and ilium are fused, forming a continuous ventral plate. The femur has a long, thin shaft and is rather straight, not bowed. The fibula is splint-like and very reduced, not reaching the tarsus. Discussion Several features indicate that Hamipterus is a member of the derived pterodactyloid clade Pteranodontoidea (warped deltopectoral crest, triangular-shaped distal syncarpal, spikelike neural spine of cervical vertebrae, coracoid larger than the scapula [11, 17]). Within that group, it differs from Pteranodon and related taxa [17, 19] in having teeth, a stout scapula with a constricted shaft, and a radius of diameter less than half that of the ulna. Hamipterus differs from the Istiodactylidae in its dentition, rostral margin, and skull openings [20]. Finally, it is also not a member of the Anhangueridae due to its distinct premaxillary crest and lack of a dentary crest, among other differences [11, 21] (Figures 1, 2, 3, 7, S2, and S3). So far, Hamipterus is the first pterosaur recorded from the Turpan-Hami Basin. The Junggar Basin, located north of the Tian Shan Mountains, has yielded a long-tailed pterosaur from the Late Jurassic, Sericipterus [22], and three genera from the Early Cretaceous, Dsungaripterus, Noripterus, and Lonchognathosaurus, regarded as part of the Dsungaripteridae and the Wuerho pterosaur fauna [13, 23, 24]. Hamipterus differs from dsungaripterids in its dentition, rostrum, cranial

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

6 Current Biology Vol 24 No 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. a member of the peculiar nonpterodactyloid clade Wukongopteridae [36]. Of these, the only one showing an external eggshell ornamentation was the first [5], suggesting that it had an external calcareous layer. However, subsequent studies considered this and the other eggs recovered from China as being soft-shelled [6, 8, 34, 35]. The fourth reported egg comes from the monospecific Pterodaustro beds of the Lower Cretaceous Lagarcito Formation in Argentina [7]. This egg s preservation differs from that of the others by showing fragmentary pieces of a thin (30 mm) calcareous hard eggshell above an embryo [34], casting some doubts as to whether the shell was continuous or patchy [35]. Compared with those specimens, the Hamipterus eggs differ in that they are tridimensional, with a calcareous hard eggshell followed by a soft membrane, similar to some snakes and lizards [33], which might also be the case for Pterodaustro eggs (pending the discovery of a complete specimen). Calcite crystals with vesicles are also found in Hamipterus eggs, but no V-shaped calcium carbonate units or other similarities to crocodylomorph eggs [34] (Figure 5). In any case, we regard the eggshell structure found in Hamipterus 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 dimensions 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 behavior. Hamipterus likely made its nesting grounds on the shores of freshwater lakes or rivers and buried its eggs in sand along the shore, preventing them from being desiccated. Further questions regarding matters such as colonial nesting, fidelity to nesting grounds, and clutch and parental care remain open, but sites like the one reported here provide further evidence regarding the behavior and biology of this amazing group of flying reptiles that has no parallel in modern time. Experimental Procedures Materials Approximately 40 individual new specimens of Hamipterus housed at IVPP were studied, including three-dimensionally preserved cranial and postcranial elements and five eggs. Phylogenetic Analysis of Pterosaurs Phylogeny was analyzed with PAUP* v4.0b10 for Microsoft Windows [37] using TBR heuristic searches and maximum parsimony. Characters were given equal weight and treated unordered (ACCTRAN setting). The data

7 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 tianshanensis is ? ? ?110101???1111??002??? ?????????. SEM and EDS Analysis Eggs of Hamipterus and Elaphe were cut longitudinally and gilded with carbon (increasing the carbon percentage without affecting the conclusions in our analysis). The samples were then observed with a Hitachi S-3700N scanning electron microscope, and EDS analysis was performed with an Oxford Instruments INCA x-act. Supplemental Information Supplemental Information includes seven figures and four tables and can be found with this article online at 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 Figure 7. Strict Consensus Tree of Pterosaur Phylogeny, Using 324 Equally Parsimonious Trees with a Length of 217 Steps Hamipterus tianshanensis gen. et sp. nov. is in the monophyletic group Pteranodontoidea. Data are based on a previous study [16]. 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. Codorniú (Universidad Nacional de San Luis, Argentina), G. Dyke (University of Southampton), S.C. Bennett (Fort Hays State University), and two anonymous reviewers for several suggestions that were incorporated in earlier versions of this manuscript. This study was supported by the National Science Fund for Distinguished Young Scholars ( ), 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 Fundaçãode Amparo à Pesquisa do Espírito Santo (FAPES /2011), and A.W.A.K. acknowledges founding from the Fundação Carlos Chagas Filho de Amparo à Pesquisa do Rio de Janeiro (FAPERJ E-26/ /2012) and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq /2009-9).

8 Current Biology Vol 24 No Received: April 13, 2014 Revised: April 25, 2014 Accepted: April 25, 2014 Published: June 5, 2014 References 1. Wellnhofer, P. (1991). The Illustrated Encyclopedia of Pterosaurs (London: Salamander Books). 2. Bell, C.M., and Padian, K. (1995). Pterosaur fossils from the Cretaceous of Chile: evidence for a pterosaur colony on an inland desert plain. Geol. Mag. 132, Chiappe, L.M., Rivarola, D., Romero, E., Davila, S., and Codorniu, L. (1998). Recent advances in the paleontology of the Lower Cretaceous Lagarcito Formation (Parque Nacional Sierra de Las Quijadas, San Luis, Argentina). In Lower and Middle Cretaceous Terrestrial Ecosystems (New Mexico Museum of Natural History and Science Bulletin 14), S.G. Lucas, J.I. Kirkland, and J.W. Estep, eds. (Albuquerque: New Mexico Museum of Natural History and Science), pp Kellner, A.W.A., Campos, D.A., Sayão, J.M., Saraiva, A.A.F., Rodrigues, T., Oliveira, G., Cruz, L.A., Costa, F.R., Silva, H.P., and Ferreira, J.S. (2013). The largest flying reptile from Gondwana: a new specimen of Tropeognathus cf. T. mesembrinus Wellnhofer, 1987 (Pterodactyloidea, Anhangueridae) and other large pterosaurs from the Romualdo Formation, Lower Cretaceous, Brazil. An. Acad. Bras. Cienc. 85, Wang, X.L., and Zhou, Z.H. (2004). Palaeontology: pterosaur embryo from the Early Cretaceous. Nature 429, Ji, Q., Ji, S.A., Cheng, Y.N., You, H.L., Lü, J.C., Liu, Y.Q., and Yuan, C.X. (2004). Palaeontology: pterosaur egg with a leathery shell. Nature 432, Chiappe, L.M., Codorniú, L., Grellet-Tinner, G., and Rivarola, D. (2004). Palaeobiology: Argentinian unhatched pterosaur fossil. Nature 432, Lü, J.C., Unwin, D.M., Deeming, D.C., Jin, X.S., Liu, Y.Q., and Ji, Q. (2011). An egg-adult association, gender, and reproduction in pterosaurs. Science 331, Eberth, D.A., Donald, B.B., Chen, P.J., Yuan, F.T., Wu, S.Z., Gang, L., and Cheng, X.S. (2001). Sequence stratigraphy, paleoclimate patterns, and vertebrate fossil preservation in Jurassic-Cretaceous strata of the Junggar Basin, Xinjiang Autonomous Region, People s Republic of China. Can. J. Earth Sci. 38, Shen, Y.B., and Mateer, N.J. (1992). An outline of the Cretaceous system in northern Xinjiang, western China. In Aspects of Nonmarine Cretaceous Geology, J.M. Niall and P.J. Chen, eds. (Beijing: China Ocean Press), pp Kellner, A.W.A. (2003). Pterosaur phylogeny and comments on the evolutionary history of the group. In Evolution and Palaeobiology of Pterosaurs, Volume 217, Buffetaut, E., and Mazin, J.-M., eds. (London: Geological Society), pp Rodrigues, T., and Kellner, A.W.A. (2013). Taxonomic review of the Ornithocheirus complex (Pterosauria) from the Cretaceous of England. Zookeys 308, Young, C.C. (1973). [Pterosaurs from Wuerho]. Mem. IVPP Acad. Sin. A 11, Bennett, S.C. (1992). Sexual dimorphism of Pteranodon and other pterosaurs, with comments on cranial crests. J. Vertebr. Paleontol. 12, Kellner, A.W.A., and Tomida, Y. (2000). Description of a new species of Anhangueridae (Pterodactyloidea) with comments on the pterosaur fauna from the Santana Formation (Aptian-Albian), Northeastern Brazil. Nat. Sci. Mus. Monogr. 17, Wang, X.L., Kellner, A.W.A., Jiang, S.X., and Cheng, X. (2012). New toothed flying reptile from Asia: close similarities between early Cretaceous pterosaur faunas from China and Brazil. Naturwissenschaften 99, Bennett, S.C. (2001). The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Part 1. General description and osteology. Palaeontographica 260, Bennett, S.C. (1989). A pteranodontid pterosaur from the Early Cretaceous of Peru, with comments on the relationships of Cretaceous pterosaurs. J. Paleontol. 63, Kellner, A.W.A. (2010). Comments on the Pteranodontidae (Pterosauria, Pterodactyloidea) with the description of two new species. An. Acad. Bras. Cienc. 82, Howse, S.C.B., Milner, A.R., and Martill, D.M. (2001). Pterosaurs. In Dinosaurs of the Isle of Wight, D.M. Martill and D. Naish, eds. (London: Palaeontological Association), pp Anders, B., and Ji, Q. (2008). A new pterosaur from the Liaoning Province of China, the phylogeny of the Pterodactyloidea, and convergence in their cervical vertebrae. Palaeontology 51, Andres, B., Clark, J.M., and Xu, X. (2010). A new rhamphorhynchid pterosaur from the Upper Jurassic of Xinjiang, China, and the phylogenetic relationships of basal pterosaurs. J. Vertebr. Paleontol. 30, Maisch, M.W., Matzkea, A.T., and Sun, G. (2004). A new dsungaripteroid pterosaur from the Lower Cretaceous of the southern Junggar Basin, north-west China. Cretaceous Res. 25, Lü, J.C., Azuma, Y., Dong, Z.M., Barsbold, R., Kobayashi, Y., and Lee, Y.N. (2009). New material of dsungaripterid pterosaurs (Pterosauria: Pterodactyloidea) from western Mongolia and its palaeoecological implications. Geol. Mag. 146, Bennett, S.C. (2007). A review of the pterosaur Ctenochasma: taxonomy and ontogeny. Neues Jahrb. Geol. Palaontol. Abh. 245, Fairbairn, D.J., Blanckenhorn, W.U., and Székely, T., eds. (2007). Sex, Size and Gender Roles: Evolutionary Studies of Sexual Size Dimorphism (Oxford: Oxford University Press). 27. Wang, X.L., Kellner, A.W.A., Jiang, S.X., Cheng, X., Meng, X., and Rodrigues, T. (2010). New long-tailed pterosaurs (Wukongopteridae) from western Liaoning, China. An. Acad. Bras. Cienc. 82, Hone, D.W., Naish, D., and Cuthill, I.C. (2012). Does mutual sexual selection explain the evolution of head crests in pterosaurs and dinosaurs? Lethaia 45, Knell, R.J., Naish, D., Tomkins, J.L., and Hone, D.W. (2013). Sexual selection in prehistoric animals: detection and implications. Trends Ecol. Evol. 28, Padian, K., and Horner, J.R. (2013). Misconceptions of sexual selection and species recognition: a response to Knell et al. and to Mendelson and Shaw. Trends Ecol. Evol. 28, Zhou, Z.Y., and Zhou, Y.F. (2004). [Preliminary observations on ecology of Elaphe schrenckii (Strauch)]. Sichuan J. Zool. 23, Ford, N.B., and Siegel, R.A. (1989). Relationships among body size, clutch size, and egg size in three species of oviparous snakes. Herpetologica 45, Schleich, H., and Kästle, W. (1988). Reptile Egg-Shells SEM Atlas (Stuttgart: Gustav Fisher Verlag). 34. Grellet-Tinner, G., Wroe, S., Thompson, M.B., and Ji, Q. (2007). A note on pterosaur nesting behavior. Hist. Biol. 19, Unwin, D.M., and Deming, D.C. (2008). Pterosaur eggshell structure and its implications for pterosaur reproductive biology. Zitteliana 28, Wang, X.L., Kellner, A.W.A., Jiang, S.X., and Meng, X. (2009). An unusual long-tailed pterosaur with elongated neck from western Liaoning of China. An. Acad. Bras. Cienc. 81, Swofford, D.L. (2008). PAUP*: Phylogenetic Analysis Using Parsimony (and Other Methods), v4.0b10 (Sunderland: Sinauer).

9 Current Biology, Volume 24 Supplemental Information Sexually Dimorphic Tridimensionally Preserved Pterosaurs and Their Eggs from China Xiaolin Wang, Alexander W.A. Kellner, Shunxing Jiang, Qiang Wang, Yingxia Ma, Yahefujiang Paidoula, Xin Cheng, Taissa Rodrigues, Xi Meng, Jialiang Zhang, Ning Li, and Zhonghe Zhou

10 Supplemental Data (1) Figures Figure S1. Related to Figure 1. Hamipterus tianshanensis gen. et sp. nov. (IVPP V18934) An articulated upper and lower jaw (IVPP V ) in lateral view, a second incomplete skull (IVPP V ) in lateral view, and an incomplete lower jaw (IVPP V ) in dorsal view, scale bar, 5 cm. lj, lower jaw; phd4, indeterminate wing phalanx; sca-cor, scapulocoracoid; sk, skull.

11 Figure S2. Related to Figure 3. Male and female skulls of Hamipterus tianshanensis gen. et sp. nov. (A) IVPP V (B) IVPP V (C) IVPP V (D) IVPP V (E) IVPP V (F) IVPP V (A, B and C) Males. (D, E and F) Females (F shown inverted). Male skulls have larger and thicker crests than those of female skulls; the male crests also have more strongly curved anterior margins than those of the females and are positioned more anteriorly. All scale bars, 5 cm. Figure S3. Related to Figure F4. Hamipterus tianshanensis gen. et sp. nov. A mandible (IVPP V ) in different views, scale bar, 5 cm. (A) In dorsal view. (B) In ventral

12 view. (C) In right lateral view. The white arrow indicates the hooked-shaped bony process on the tip of the dentary; the hollow arrow indicates the developed dentary groove reaching the tip of the dentary; the black arrow indicates the dentary fossa in the ventral surface of the lower jaw. Figure S4. Related to Figure F4. Hamipterus tianshanensis gen. et sp. nov. Three ulnas of different sizes in posterior view, showing that there are no significant variations during ontogeny. (A) IVPP V , left ulna. (B) IVPP V , right ulna. (C) IVPP V , left ulna. Scale bar, 5 cm.

13 Figure S5. Related to Figure 2. Hamipterus tianshanensis gen. et sp. nov. Distal lateral carpals, white arrows indicating the spike-like processes. (A and C) IVPP V , right distal lateral carpal. (B and D) IVPP V , left distal lateral carpal. (A and B) in lateral view. (C and D) in medial view. Scale bar, 1 cm. Figure S6. Related to Figure 5. The smallest egg (IVPP V13938) of Hamipterus tianshanensis gen. et sp. nov. Part (A) and counterpart (B). The small size might reflect an early stages of development. Scale bar, 1 cm.

14 Figure S7. Related to Figure 6. EDS done under SEM in three positions of the egg (IVPP V18939), indicating that main composition of the eggshell is calcium carbonate. See the details of the composition in Table S4. (2) Tables and legends Table S1. Related to Figure 3. Measurement of the skulls of Hamipterus tianshanensis gen. et sp. nov. (in cm) Specimens Length Width of the Height of the Length of Length of Length of the number of skull skull (at the skull (at the rostrum tooth row nasoantorbital (pm-sq) anterior point of the crest) anterior margin of naof) (pm-naof) fenestra V (Holotype) V V V V (Paratype) V V V V V V V Table S2. Related to Figure 4. Measurement of lower jaws of Hamipterus tianshanensis gen. et sp. nov. (in cm)

15 Specimens number Length of lower jaw Length of tooth row Length of symphysis Width of lower jaw (largest) Width of lower jaw (at the symphysis) V V V V * 14.9* 9.4* 1.4 V V * 17.6* 10.7* V * 16.2* 11.5* 1.9 V * *preserved length Table S3. Related to Figure 5. Measurement of four complete eggs of Hamipterus tianshanensis gen. et sp. nov. (in mm) Specimens Length Width number IVPP V IVPP V IVPP V IVPP V Table S4. Related to Figure 6. Composition of elements tested in EDS. See the tested positions in Figure S7. No.1 No.2 No.3 A B C A B C A B C C K C K C K O K O K O K Na K Al K Mg K Mg K Si K Al K Al K P K Si K Si K Cl K P K P K Ca K Cl K Cl K K K Ca K Ca K Fe K Total 100 Total 100 Total 100 A, Element; B, Mass Percentage; C, Atomic Percentage.