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1. chinaXiv:201812.00009 [pdf]

The posterior cranial portion of the earliest known Tetrapodomorph Tungsenia paradoxa and the early evolution of tetrapodomorph endocrania

LU Jing; YOUNG Gavin; HU Yu-Zhi; QIAO Tuo; ZHU Min
分类: 生物学 >> 生物学其他学科

Abstract Here the posterior cranial portion of the tetrapodomorph Tungsenia from the Lower Devonian (Pragian, ~409 million years ago) of Yunnan, southwest China, is reported for the first time. The pattern of posterior skull roof and the morphology of the otoccipital region of the neurocranium are described in detail, providing precious insight into the combination of cranial characters of the earliest known tetrapodomorph to date. The posterior cranium of Tungseniadisplays a mosaic of features previously linked either to basal dipnomorphs such as Youngolepis(e.g., the well-developed subjugular ridge, the strong adotic process, and the poorly developed fossa bridgei) or to typical tetrapodomorphs (e.g., the lateral dorsal aortae commenced from the median dorsal aorta postcranially). The independent ventral arcual plate is also found in the advanced tetrapodomorph Eusthenopteron. The new endocranial material of Tungsenia further fills in the morphological gap between Tetrapodomorpha (tetrapod lineage) and Dipnomorpha (lungfish lineage) and unveils the sequence of character acquisition during the initial diversification of the tetrapod lineage. The new phylogenetic analysis strongly supports the basalmost position of Tungsenia amongst the tetrapod lineage.

提交时间: 2018-12-04 来自合作期刊:《古脊椎动物学报》 点击量274下载量130 评论 0

2. chinaXiv:201711.01898 [pdf]

A new mimotonidan Mina hui (Mammalia, Glires) from the Middle Paleocene of Qianshan, Anhui, China

LI Chuan-Kui; WANG Yuan-Qing; ZHANG Zhao-Qun; MAO Fang-Yuan1MENG Jin
分类: 生物学 >> 动物学

Here we report a new genus and species, Mina hui gen. et sp. nov., of basal Glires from the Middle Paleocene of Qianshan, Anhui, China. The new taxon is characterized by combination of the following characters: medium-sized mimotonidan; upper dental formula 2.0.3.3; d I2 transversely narrow and having smooth labial surface without longitudinal groove; M1 the largest cheek tooth and other cheek teeth decreasing in size considerably away from M1 so that the external margin of the upper cheek tooth row is distinctly arched labially; lingual side of upper molars unilaterally hypsodont and bearing no hypostria; hypocone being slightly distolingual to protocone; presence of a mesostyle; upper incisor with double-layered enamel structure; posterior border of anterior root of zygoma situated lateral to M1–2 and infraorbital foramen positioned low. M. hui is one of the earliest known Glires, co-existing with Heomys and Mimotona in Qianshan geographically and Middle Paleocene (ca. 61 Ma) chronologically. We consider that the Mimotonida would include two families: the monotypic Mimotonidae that contains Mimotona and Mimolagidae that includes Mimolagus, Gomphos, Anatolimys, Mina and possibly Amar aleator. Among known mimotonidans, Mimotona probably represents a primitive “morphotype” as the ancestor of lagomorphs, whereas Mimolagidae includes a side branch diverged from the clade evolved toward lagomorphs. Future research may show that Mimolagidae is not a natural group, and may possibly submerge into Mimotonida, or involve more than one family-level clade. The occurrence of Heomys, Mimotona and Mina from Qianshan show that Glires had already diversified by the Middle Paleocene.

提交时间: 2017-11-07 来自合作期刊:《古脊椎动物学报》 点击量723下载量190 评论 0

3. chinaXiv:201711.01901 [pdf]

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

SHI Qin-Qin; WANG Shi-Qi; CHEN Shao-Kun; LI Yi-Kun
分类: 生物学 >> 动物学

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 of Urmiatherium 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.

提交时间: 2017-11-07 来自合作期刊:《古脊椎动物学报》 点击量767下载量208 评论 0

4. chinaXiv:201711.01908 [pdf]

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

ZHANG Zhao-Qun WANG Jian
分类: 生物学 >> 动物学

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 Anagale from 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.

提交时间: 2017-11-07 来自合作期刊:《古脊椎动物学报》 点击量390下载量132 评论 0

5. chinaXiv:201711.01910 [pdf]

New material of the Early Pleistocene mammalian fauna from Chutoulang, Chifeng, eastern Nei Mongol, China and binary faunal similarity analyses

DONG Wei; ZHANG Li-Min; LIU Wen-Hui
分类: 生物学 >> 动物学

New specimens from a new locality at Chutoulang in eastern Nei Mongol were identified as Canis chihliensis, Coelodonta nihowanensis, Hipparion (Proboscidipparion) sinense, Equus sanmeniensis, Sus lydekkeri, Muntiacus cf. M. lacustris, Axis shansius, Eucladoceros boulei, Spirocerus cf. S. wongi and Bison palaeosinensis. They enriched the mammalian fauna of Chutoulang to 30 taxa together with the material from Dongliang, Dongcun Beigou and Dongcun Nangou localities. The mammalian fossils from these four localities are all from the same horizon and can be regarded as the same fauna, i.e. Chutoulang fauna. The composition of Chutoulang fauna is the closest to that of Nihewan (s.s.) by binary faunal similarity coefficients. The age of Chutoulang fauna is between those of Nihewan (s.s.) and Juyuandong at Liucheng according to Brainerd-Robinson’s sequence, extinction rates and antiquity coefficients. The numerical age of Chutoulang fauna is estimated between 1.4–1.6 Ma based on those of compared faunas. Carnivora are the most numerous in Chutoulang fauna with 11 taxa, but mostly the small sized ones. Perissodactyla and Artiodactyla make about half of the fauna. They are mostly large sized forms. The presence of numerous browsers or forest dwellers implies the existence of forest or woodland in Chutoulang area during that period. The presence of grazers and openland dwellers indicates the existence of larger area of grassland or steppes than that of woodland or forests. Most members of Chutoulang fauna are temperate habitat dwellers with a few cold-prone forms such as Ochotona and Coelodonta. The climate in Chutoulang area in the Early Pleistocene was thus similar to that of today. Chutoulang fauna is the most northeastern Early Pleistocene fauna in China and it can be recommended as a type site of the Early Pleistocene mammalian fauna in northeastern China.

提交时间: 2017-11-07 来自合作期刊:《古脊椎动物学报》 点击量432下载量149 评论 0

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