Table of Content

15 March 2013, Volume 51 Issue 1

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Re-study on Gymnoichthys inopinatus from Middle Triassic of Luoping, Yunnan, China

TAN Kai, JIN Fan

2013, 51(1):  1-16. 

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Gymnoichthys inopinatus was initially described by Tintori et al. in 2010, and regarded as a basal neopterygian. According to the new material of the Middle Triassic Guanling Formation discovered in Dawazi Village, Luoping County, Yunnan Province, China, we redescribed G. inopinatus, and re-identified its systematic position. G. inopinatus has only one supramaxilla and its symplectic is likely jointed with the articular, which are the identifying characters of Halecomorphi. Morever, G. inopinatus has no scales, its vertebral centra are not ossified, and the structure and relationship of the neural arches and neural spines, as well as the shape of teeth and ural haemal spines in G. inopinatus are quite like that of the caturoids. Hence, it is suggested to consider G. inopinatusas a basal form of the superfamily Caturoidea. Previously, caturoids were only discovered in the Jurassic of Europe and North America, and its recognized forms included Liodesmus, the only genera of the family Liodesmidae, and Caturus and Amblysemius of the family Caturidae. Gymnoichthys inopinatus is not only the first caturoid found in China, but also the earliest caturoid in the world, which is 40 million years earlier than the European and North American caturoids.

ON THE TAXONOMY OF XINPUSAURUS (REPTILIA: THALATTOSAURIA)

LIU Jun

2013, 51(1):  17-23. 

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 After examining the holotypes and the referred specimens of three species of Xinpusaurus, I conclude that the snout and the shape of the dentary cannot be used to differentiate the known species ofXinpusaurus and that the postcranial diagnostic characters of X. kohi cannot be confirmed because of the poor preservation; so both X. bamaolinensis and X. kohi should be junior synonyms of X. suni. The anatomy of the braincase of this taxon is further clarified. 

A new thalattosaur, Concavispina biseridens gen. et sp. nov. from Guanling, Guizhou, China

ZHAO Li-Jun, LIU Jun, LI Chun, HE Tao

2013, 51(1):  24-28. 

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A new thalattosaur, Concavispina biseridens gen. et sp. nov., is established on the basis of a new skeleton from Xiaowa Formation of Guangling, Guizhou, China. It is diagnosed by two rows of blunt teeth on anterior part of maxilla and V-shaped notch on the dorsal margin of neural spines in dorsal vertebrae. It shares three derived characters only with Xinpusaurus: anterior end of maxilla curved dorsally; cervical vertebrae less than five; proximal end of humerus wider than distal end. This indicates that the new taxon may have a closely relationship withXinpusaurus.

A large theropod metatarsal from the upper part of Jurassic Shishugou Formation in Junggar Basin, Xinjiang, China

HE Yi-Ming, James M. CLARK, XU Xing

2013, 51(1):  29-42. 

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The Shishugou Formation in the Junggar Basin was deposited during the late Middle Jurassic to the early Late Jurassic. It is known as a rich source of vertebrate fossils, including specimens of several different kinds of theropod. Here we report an isolated theropod left metatarsal IV (IVPP V 18060) from the upper part of the Shishugou Formation, exposed at the Wucaiwan Locality in the northeastern part of the Junggar Basin. Based on comparisons with the fourth metatarsals of other theropods, we refer this specimen to Allosauroidea. Similarities to the equivalent bone in other allosauroids include: the proximal end has a subtriangular outline with a tongue-like, posteriorly directed posteromedial process; the shaft has a gentle outward curve; a semi-lunate concave of muscle attachment is present on the posterolateral side of the shaft; and the cross-section of the shaft is triangular. Within Allosauroidea, V 18060 is most similar to the fourth metatarsal of Sinraptor dongi, a taxon that occurs in the same formation in the Jiangjunmiao area of the Junggar Basin. V18060 displays several specific resemblances to S. dongi: the outline of the distal end is subtrapezoidal; the depression for muscle attachment on the posterior side of the shaft that borders the shaft’s lateral side lacks a well defined ridge. However, V 18060 also differs in some respects from the fourth metatarsal of S. dongi: V 18060 is much more robust, and the lateral condyle on the distal end is smaller than the medial one. These morphological differences could be ontogenetic variation or due to sexual dimorphism, taxonomical variations. We prefer the interpretation that V 18060 is a new species that has a close relationship to S. dongi, and a cladistic analysis based on the morphology of metatarsal IV supports this inference. The discovery of V 18060 suggests that the theropods from the Shishugou Fauna are more diversified during the Mid-Late Jurassic than previously thought. The presence of different sinraptorid species in the neighboring areas of Wucaiwan and Jiangjunmiao points to the possibility that these two regions within the Junggar Basin were geographically isolated or ecologically distinct from one another during the Mid-Late Jurassic.

NEW FORMS OF DICTYOOLITHIDS FROM THETIANTAI BASIN, ZHEJIANG PROVINCE OF CHINAAND A PARATAXONOMIC REVISION OF THE DICTYOOLITHIDS

WANG Qiang, ZHAO Zi-Kui, WANG Xiao-Lin, ZHANG Shu-Kang,JIANG Yan-Gen

2013, 51(1):  43-54. 

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 Dinosaur eggs collected from the Upper Cretaceous Chichengshan Formation in the Tiantai Basin of Zhejiang Province are referable to the oofamily Dictyoolithidae. On the basis of general external shape, size, eggshell thickness, and eggshell composed of 3−4 superimposed slender shell units with a reticulate organization, a new oogenus and two oospecies, Paradictyoolithus zhuangqianensisoogen. et oosp. nov., and P. xiaxishanensis oogen. et oosp. nov., are erected. The Dictyoolithidae is previously represented by one oogenus and four oospecies, Dictyoolithus hongpoensis, D.neixiangensis, D. jiangi, and D. gongzhulinensis, all of which are known exclusively from the Cretaceous of China. We re-examined the holotypes of the four oospecies, established a new oogenusProtodictyoolithus, and propose that only D. hongpoensis belong to the Dictyoolithus, the other three species of Dictyoolithus should be reassigned to Protodictyoolithus neixiangensis comb. nov., P. jiangicomb. nov. and Similifaveoolithus gongzhulingensis comb. nov., respectively.

MYLAGAULIDS (MAMMALIA: RODENTIA) FROM THE EARLY MIDDLE MIOCENE OF NORTHERNJUNGGAR BASIN

WU Wen-Yu, NI Xi-Jun, YE Jie, MENG Jin, BI Shun-Dong

2013, 51(1):  55-70. 

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Application of CT (computed tomography) scanning technology to the study of tooth morphology of mylagaulids makes better understanding the tooth structure of high-crowned mylagaulids. Two genera and species from the early Middle Miocene Halamagai Formation in northern Junggar Basin ofXinjiang are recognized: Tschalimys ckhikvadzei Shevyreva, 1971, the senior synonym of Sinomylagaulus halamagaiensis Wu, 1988 and Simpligaulus yangigen. et sp. nov. Both taxa undoubtedly belong to the subfamily Promylagaulinae. The integrated lithological, paleontological and paleomagnetic studies on sediments of the Late Oligocene through Late Miocene in the northern Junggar Basin of Xinjiang demonstrate that Halamagai Formation is fluvial-lacustrine sediments formed during the time coincident to the Mid-Miocene Climatic Optimum. T. ckhikvadzei and S. yangi probably inhabit the humid and warm regions with forests and densely vegetated thickets as the living mountain beaver Aplodontia rufa does. These mylagaulids are probably immigrants or the descendants of the immigrants from west North America.

Gomphotherium wimani from Wushan County, China, and its implications for the Miocene stratigraphy of the Tianshui area

WANG Shi-Qi, LIU Shan-Pin, XIE guang-Pu, LIU Jia, PENG Ting-Jiang, HOU Su-Kuan

2013, 51(1):  71-84. 

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A fragmentary juvenile mandible referable toGomphotherium wimani is described in this report. It was discovered at the Nanyucun Locality, Simen Township, wushan County, Tianshui area, gansu Province. Both the left and right p3, dp4, and m1 are completely preserved in this specimen. The cheek teeth show characters that are derived within the genus Gomphotherium, such as anteroposterior compression of lophids associated with wide interlophids, presence of weak posttrite central conules, multiplication of mesoconelets and central conules, and weak cementation. These features are consistent with the diagnosis of G. wimani. G. wimani was originally discovered in the Middle Miocene of gansu, and the fossiliferous horizon within the Nanyucun exposures that yielded G. wimani can be correlated with strata at neighboring Middle Miocene localities. Therefore, the G. wimanihorizon at Nanyucun should be dated to the Middle Miocene. In combination with palynological data, the discovery of G. wimani at the Nanyucun Locality implies that the paleoenvironment of the Tianshui area in the Middle Miocene was probably relatively warm and humid, suitable for large populations of brachyodont mammals such as gomphotheres.