Keichousaurus

Abstract: The first Triassic sauropterygian to be described from China was Keichousaurus hui (Young, 1958) found in Xingyi, Guizhou. Shingyisaurus unexpectus, another sauropterygian found in Xingyi, Was referred to the Simosauridae by Young (1965). It was identified as Nothosaurus or a closely related gnus, and the name Shingyisaurus unexpectus was considered a nomen dubium (Rieppel, 1998). Here we report a well-preserved specimen from Xingyi, Guizhou Province. It represents the first undoubted specimen and a new species of Lariosaurus ever found outside western Tethyan faunal province.

Abstract: A new eosauropterygian,Dianmeisaurus gracilis gen.et sp.nov.is described based on a nearly complete skeleton from the Member Ⅱ of Guangling Formation(Anisian) of Luoping County,Yunnan Province.It is a small-sized(with a total length of less than 50 cm)sauropterygian with a slender body.This new species is similar superficially to two other smallsized eosauropterygians,Diandongosaurus Shang et al.,2011 and Dianopachysaurus Liu et al.,2011 a,which were also collected from the same stratum of Luoping,in the body proportion,the skull with no contracted snout,and an oval orbit extremely larger than supratemporal fenestra.However,the new species is characterized by an extremely narrowed interorbital septum,the mandibular articulation at the level of occipital condyle,the big and stout anterolateral process of the clavicle,the proximal part of the ulna much wider than the distal end,and the presence of 41 presacral vertebrae.Furthermore,the new species differs from Diandongosaurus in having the preorbital region shorter than the postorbital region,the prefrontal with no contact of the postfrontal along the dorsal margin of the orbit,the short mandibular symphysis with the entrance of the splenial,and the premaxillary and anterior dentary teeth fang like but not king-sized.Additionally,the anterolateral process of the clavicle is very sharp and slender in Diandongosaurus.Compared with the Dianopachysaurus,the new species is different in having no pachyostosis of the caudal ribs,no more than three carpal ossifications,and the rounded astragalus.Our phylogenetic analyses suggest that Dianmeisaurus is probably the sister group of Diandongosaurus.The two genera,together with the Majiashanosaurus,Keichousaurus,and Dianopachysaurus are grouped in a monophyletic clade and phylogenetically more closely related to the Nothosauroidea than the European pachypleurosaurs(Dactylosaurus,Anarosaurus,Serpianosaurus,and Neusticosaurus).The coexist of three small-sized eosauropterygians indicates that sauropterygians were a highly diversified group of marine reptiles in the Luoping fauna,Yunnan Province during the early Middle Triassic.

Abstract: In the fifties of last century Mr Su De Zao (former Su Te Tsao) of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, first described three genera and species of fishes from the Keichousaurus bearing horizon in Xingyi of Guizhou, they are Peltopleurus orientalis Su, 1959, Sinoeugnathus kueichowensis Su, 1959, and Asialepidotus shingyiensis Su, 1959 The then five incomplete fish fossils were collected in 1957 by Mr Cao Zhe Tian of the Guizhou Museum at Langmu, Dazhai village, Tingxiao of Xingyi Later on, nobody had made futher investigations and studies for more than two decades It is an interesting comment in the eighties of last century that the search for fantastic stones let to the discovery of abundant and diversified fish fossils from the Keichousaurus bearing horizon in Xingyi of Guizhou It is very fortunate that we collected some complete and beautiful specimens of fish fossils from a lot of collectors and dealers in fantastic stone Moreover, in 2001 and in 2002 we went Xingyi to do field exploring and confirmed that they occur really in the Keichousaurus bearing horizon One among them, that was used as the holotype of a new genus and species of the family Amiidae, had been described initially in 2002 by the first three authors of this paper, and some supplementary descriptions and necessary discussions will be made in this paper These new discoveries of great importance have helped us more understanding of the fishes from the Keichousaurus bearing horizon, and moreover, the characters of a distinctive fish fauna of the Late Triassic in Xingyi of Guizhou also have appeared more enough The new forms and new material of Guizhouamia from the Keichousaurus bearing horizon are deseribed as follows

Abstract: The Choristodera is a poorly known clade, but very a distinctive group of aquatic reptiles, which has been found from the Late Triassic to the Late Oligocene in Asia, North America and Europe. Although thousands of choristoderian specimens have been collected from the Early Cretaceous non-marine beds in Liaoning, China, no direct evidences have been found to determine whether they were oviparous like sea turtles or viviparous like Keichousaurus hui of Pacbypleurosauria (marine reptiles). Here we report a well-preserved specimen of Hyphalosaurus baitaigouensis with leathery embryonic eggs from the Jiufotang Formation in western Liaoning, China. It provides the first direct evidence to indicate that choristoderian reptiles are most likely viviparous like Late Triassic Keichousaurus hui from Guizhou, Southern China.