Table of Content

15 December 2016, Volume 54 Issue 4

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A new microraptorine specimen (Theropoda: Dromaeosauridae) with a brief comment on the evolution of compound bones in theropods

XU Xing, LI Feng

2016, 54(4):  269-285. 

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Microraptorinae is a recently discovered subgroup of dromaeosaurid theropods, mostly comprising species from the Lower Cretaceous Jehol Group of western Liaoning, China. Here we describe a new microraptorine specimen from the Jiufotang Formation (the upper section of the Jehol Group) of Dapingfang, Chaoyang, Liaoning, which displays interesting morphological features not previously documented within Microraptorinae. Noteworthy are several osteological features, including dental and ischial ones, which are transitional between the condition of Sinornithosaurus and that of Microraptor. These features highlight the existence of a spectrum of morphological variation between Sinornithosaurus, which is more like a typical dromaeosaurid, andMicroraptor, which shares many characteristics with troodontids. However, the taxonomic significance of these variations has not to be fully assessed yet. A feature deserving special mention is the fusion of the pubes to the ilia in this specimen, which has implications for the evolution of compound bones in theropods+. Our preliminary analysis suggests that many compound bones in birds have been formed by sequential fusion of multiple elements in a peramorphic process.  

Sciurid remains from the Late Cenozoic fissure-fillings of Fanchang, Anhui, China 

QIU Zhu-Ding    JIN Chang-Zhu 

2016, 54(4):  286-301. 

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 Remains of sciurids from a late Cenozoic fissure in Anhui, China are described. Six taxa, including one new genus and two new species, representing five genera and four tribes in the subfamily Sciurinae are recognized. They are Sciurus sp., Tamias sp., Plesiosciurus zhengi sp. nov.,Sciurotamias wangi Qiu, 2002, S. teilhardi Zheng, 1993, and Pseudoratufa wanensis gen. et sp. nov. The material described was collected from four levels of the fissure fillings. On the basis of the fossil content and coloration, the collection is considered to be a mixed sample with elements representing a rather long interval, probably ranging from the Early Miocene to the Pleistocene. The assemblage shows similar traits of the late Cenozoic sciurine faunas from central and southern China, and contains an intriguing genusPseudoratufa. Characters of the latter’s dentition clearly demonstrate that the new-comer of ratufin is a tree squirrel; Pseudoratufa is probably coeval with the Fanchang hominoid, and with Diatomys and beavers found in this fissure. The joint occurrence of these taxa seems to be indicative of existence of forest biotopes once in this district during the earlier Miocene. 

A skull of Machairodus horribilis and new evidence for gigantism as a mode of mosaic evolution in machairodonts (Felidae, Carnivora)

DENG Tao, ZHANG Yun-Xiang, Zhijie J. TSENG,  HOU Su-Kuan

2016, 54(4):  302-318. 

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Sabertooth cats were extinct carnivorans that have attracted great attention and controversy because of their unique dental morphology representing an entirely extinct mode of feeding specialization. Some of themare lion-sized or tiger-sized carnivorans who are widely interpreted as hunters of larger and more powerful preys than those of their modern nonsaber-toothed relatives. We report the discovery of a large sabertooth cat skull ofMachairodus horribilis from the Late Miocene of northwestern China. It shares some characteristics with derived sabertooth cats, but also is similar to extant pantherines in some cranial characters. A functional morphological analysis suggests that it differed from most other machairodont felids and had a limited gape to hunt smaller preys. Its anatomical features provide new evidence for the diversity of killing bites even within in the largest saber-toothed carnivorans and offer an additional mechanism for the mosaic evolution leading to functional and morphological diversity in sabertooth cats. 

The first discovery of Urmiatherium (Bovidae, Artiodactyla) from Liushu Formation, Linxia Basin

SHI Qin-Qin, WANG Shi-Qi, CHEN Shao-Kun, LI Yi-Kun 

2016, 54(4):  319-331. 

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 A new skull of Urmiatherium intermedium (Bovidae, Artiodactyla) from the Linxia Basin, Gansu Province is described here. U. intermedium is a large Late Miocene bovid with an odd-looking horn apparatus, consisting of a pair of degenerate, closely situated horn-cores, and a large area of exostoses on the frontal and the parietal bones. Plenty of skulls, teeth, and bone fragments of U. intermedium have been reported from North China, but the skull to be described is the first discovery from the Linxia Basin, expanding the geographic distribution of U. intermedium to the northeast edge of the Tibetan Plateau. Although Urmiatherium is generally thought to be closely related to Plesiaddax, Hezhengia, Tsaidamotherium, and some other Late Miocene “ovibovines”, the phylogenetic position ofUrmiatherium is still in debate. The distribution of Urmiatherium is wide, spanning from Iran to North China. Urmiatherium seldom accompanies with other Late Miocene “ovibovines” in North China, but is accompanied by other bovids like Sinotragus.  

New materials of micromammal fossils from Longyadong Cave in Luonan Basin, Shaanxi, central China

LI Yong-Xiang, HU Song-Mei , WANG She-Jiang , ZHANG Yun-Xiang

2016, 54(4):  332-350. 

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This paper describes some micromammal fossils which were excavated from the South Longyadong Cave in the Luonan Basin, eastern Qinling Mountains of Shaanxi Province, central China. The fauna include 15 mammals consisting by Scapanulus oweni, Nasillus andersoni, Uropsilinae gen. et sp. indet., Soriculus sp., Ochotona cf. O. alpina, Belomys parapearsoni,Allocricetus ehiki, Proedromys bedfordi, Allophaiomys deucalion, Eospalaxsp., Niviventer preconfucianus, Apodemus asianicus, Apodemus sp., Hystrix brachyura subcristata, Trogontherium cuvieri. Among them, the Nasillus andersoni and the Ochotona cf. O. alpina are the newly discovered fossil species. The fossil assemblage characteristics of newly micromammal faunal is similar to the North Longyadong Cave Fauna, and the geological age should not be later than early Middle Pleistocene. It might be a fauna of late Early Pleistocene. But in recent years, the thermoluminescence age of fossiliferous strata corresponding are 356.6±17.8 kaBP, 273.9±13.7 kaBP and 210.5±10.5kaBP. The fauna is including both the south and the north animals, the animal combination obviously has the characteristics of the transition between the south and the north of China. 

On the geological age of mammalian fossils from Shanmacheng, Gansu Province　　  

Zhang Zhao-qun,Wang Jian 

2016, 54(4):  351-357. 

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The mammalian fossils (Mimolagus and Anagalopsis) from Shanmacheng in the Jiuxi Basin described by Bohlin in 1951 have long been enigmatic in systematics and controversial in the geological age. New survey in this area suggests the fossils were discovered from the Shanmacheng member of the Huoshaogou Formation. Comparisons of the Shanmacheng fossils with new specimens of Mimolagus from the Irdin Mahan Formation, and Anagalefrom the Late Eocene Ulan Gochu Formation, Nei Mongol, suggest an Eocene age for the Shanmacheng fossils. Reinterpretation of the fossil horizon and the paleomagnetic data of Dai et al. (2005) indicates the polarity zones from Huoshaogou section can be correlated to GPTS Chrons 13−18. Therefore, the Huoshaogou Formation may cover late Middle Eocene to Late Eocene and Bohlin’s fossil horizon can roughly be correlated to Chron18n (~39−40 Ma) of late Middle Eocene. The late Middle Eocene age of Mimolagus rodens narrows the time gap with its close relative Gomphos that have been recorded from Early to Middle Eocene. The archaic group Anagalidae may have become extinct before Oligocene.