A new eosauropterygian (Diapsida: Sauropterygia) from the Middle Triassic of Luoping, Yunnan Province

Abstract

A new eosauropterygian, Largocephalosaurus polycarpon gen. et sp. nov., was described based on a skeleton from the Middle Triassic of Luoping (罗平), Yunnan (云南) Province, southwestern China. The new taxon is characterized by a big skull, paired frontal, laterally expanded upper temporal fossa, anterior process of squamosal entering orbit, robust teeth with basally expanded crown and blunt tip, short cervical region, distinctly elongated transverse process of the dorsal vertebrae, short and broad dorsal ribs, stout gastralia, scapula with distinctly posterodorsally extending blade, distinctly robust humerus, eleven carpal ossifications, and a manual fomula of 2-3-4-5-5. A phylogenetic analysis suggests that Largocephalosaurus is the basal-most member of a clade including Wumengosaurus, European pachypleurosaurs, and Nothosauroidea.

Keywords

Yunnan / Triassic / Guanling Formation / Sauropterygia

References

[1] Carroll R. L., Gaskill P.. The Nothosaur Pachypleurosaurus and the Origin of Plesiosaurs. Philosophical Transactions of the Royal Society of London B, 1985, 309(1139): 343-393.

[2] Cheng L., Chen X. H., Zhang B. M., . A New Material of Thalattosauria (Reptilia: Diapsida) from the Middle Triassic of Luoping, Yunnan Province. Earth Sciene—Journal of China University of Geosciences, 2010, 35(4): 507-511.

[3] Cheng Y. N., Wu X. C., Ji Q., . Triassic Marine Reptile Gave Birth to Live Young. Nature, 2004, 432(7015): 383-386.

[4] Cheng Y. N., Sato T., Wu X. C., . First Complete Pistosauroid from the Triassic of China. Journal of Vertebrate Paleontology, 2006, 26: 501-504.

[5] Cheng Y. N., Holmes R., Wu X. C., . Sexual Dimorphism and Life History of Keichousaurus Hui (Reptilia: Sauropterygia). Journal of Vertebrate Paleontology, 2009, 29(2): 401-408.

[6] Hao W. C., Sun Y. L., Jiang D. Y., . Advance in Studies of the Panxian Fauna. Acta Sientiarum Naturalium Universitatis Pekinensis, 2006, 42(6): 817-823.

[7] Holmes R., Cheng Y. N., Wu X. C.. New Information on the Skull of Keichousaurus Hui (Reptilia: Sauropterygia) with Comments on Sauropterygian Interrelationships. Journal of Vertebrate Paleontology, 2008, 28(1): 76-84.

[8] Jiang D. Y., Maisch M. W., Hao W. C., . Nothosaurus Yangjuanensis n. sp. (Reptilia, Sauropterygia, Nothosauridae) from the Middle Anisian (Middle Triassic) of Guizhou, Southwestern China. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte, 2006, 5: 257-276.

[9] Jiang D. Y., Maisch M. W., Sun Z. Y., . A New Species of Lariosaurus (Reptilia, Sauropterygia) from the Middle Anisian (Middle Triassic) of Guizhou, Southwestern China. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 2006, 242: 19-42.

[10] Jiang D. Y., Rieppel O., Motani R., . A New Middle Triassic Eosauropterygian (Reptilia, Sauropterygia) from Southwestern China. Jounral of Vertebrate Paleontology, 2008, 28(4): 1055-1062.

[11] Li C.. Placodont (Reptilia: Placodontia) from Upper Triassic of Guizhou, Southwest China. Vertebrata PalAsiatica, 2000, 38: 314-317.

[12] Li C., Rieppel O.. A New Cyamodontoid Placodont from Triassic of Guizhou, China. Chinese Science Bulletin, 2002, 47(5): 403-407.

[13] Li J. L., Liu J., Rieppel O.. A New Species of Lariosaurus (Sauropterygia: Nothosauridae) from Triassic of Guizhou, Southwest China. Vertebrata PalAsiatica, 2002, 40(2): 114-126.

[14] Li J. L.. A Brief Summary of the Triassic Marine Reptiles of China. Vertebrata PalAsiatica, 2006, 44(1): 99-108.

[15] Rieppel O.. The Systematic Status of Hanosaurus Hupehensis (Reptilia, Sauropterygia) from the Triassic of China. Jounral of Vertebrate Paleontology, 1998, 18(3): 545-557.

[16] Rieppel, O., 2000. Sauropterygia I: Placodontia, Pachypleurosauria, Nothosauroidea, Pistosauroidea. In: Wellnhofer, P., ed., Encyclopedia of Paleoherpetology, 12A: i–x, 1–134.

[17] Pfeil, Munich Rieppel O., Lin K.. Pachypleurosaur (Reptilia: Sauropterygia) from the Lower Muschelkalk, and a Review of the Pachypleurosauroidea. Fiadiana (Geology), 1995, 32: 1-44.

[18] Rieppel O., Sander P. M., Storrs W. G.. The Skull of the Pistosaur Augustasaurus from the Middle Triassic of Nothwestern Nevada. Journal of Vertebrate Paleontology, 2002, 22(3): 577-592.

[19] Romer A. S.. Osteology of Reptiles, 1956, Chicago: University of Chicago Press

[20] Sander P. M.. The Pachypleurosaurids (Reptilia: Nothosauria) from the Middle Triassic of Monte San Giorgio, (Switzerland), with the Description of a New Species. Philosophical Transactions of the Royal Society of London B, 1989, 325(1230): 563-670.

[21] Storrs G. W.. Anatomy and Relationships of Corosaurus Alcovensis (Diapsida: Sauropterygia) and the Triassic Alcova Limestone of Wyoming. Bulletin of the Peabody Museum of Natural History, 1991, 44: 1-151.

[22] Swofford, D. L., 2002. PAUP* 4.0b10. Phylogenetic Analysis Using Parsimony (*and Other Methods). Sinauer Associates, Sunderland, Massachusetts

[23] Wang X. F., Chen X. H., Chen L. D., . Study of the Guanling Biota in Guizhou: Progress and Problems. Geological Bulletin of China, 2003, 22(4): 221-227.

[24] Wu X. C., Cheng Y. N., Li C., . New Information on Wumengosaurus Delicatomandibularis Jiang et al., 2008 (Diapsida: Sauropterygia), with a Revision of the Osteology and Phylogeny of the Taxon. Journal of Vertebrate Paleontology, 2011, 31(1): 70-83.

[25] Young C. C.. On New Nothosaurs from Hupeh and Kweichou, China. Vertebrata PalAsiatica, 1965, 9(4): 315-356.

[26] Zhang Q., Zhou C., Lü T., . Discovery and Significance of the Middle Triassic Anisian Biota from Luoping, Yunnan Province. Geological Review, 2008, 54(4): 523-526.

[27] Zhang Q., Zhou C., Lü T., . The Revision of the Age of the Middle Triassic Luoping Biota in Yunnan: the Evidence from Conodont. Science in China (Ser. D), 2009, 39(3): 300-305.