分类： 生物学 >> 动物学 提交时间： 2021-07-21 合作期刊: 《古脊椎动物学报》
摘要： Robust regional chronostratigraphic framework is the basis of understanding climatic and faunal events in the geologic history. One of the most dramatic faunal turnovers of the past 50 million years in Asia is linked to the Eocene–Oligocene Transition (EOT) at about 34 Ma. However, the chronostratigraphic relationships between faunal modulation and geologic events associated with the EOT in China have remained uncertain before and after the epoch boundaries, mainly due to the scarcity of continuous records and problems in correlating and subdividing the classic areas containing abundant mammalian fossils. Past decades have seen developments in establishing Chinese regional Paleogene Land Mammal Ages, and albeit many ages are well constrained, some, such as those of the latest Eocene and the Oligocene, have remained unsettled. In this paper, we present how recent evidence from the fossiliferous Ulantatal sequence, Nei Mongol, China, provides better constraints to the latest Eocene and Oligocene Chinese Land Mammal ages (Baiyinian, Ulantatalian, and Tabenbulukian). We propose Ulantatal sequence as a new regional unit stratotype section of the Ulantatalian stage, and the lower boundary of Tabenbulukian stage to be reassigned to Chron C9r (27.7 Ma), with the lowest occurrence of Sinolagomys as the marker horizon.
分类： 生物学 >> 动物学 提交时间： 2021-04-02 合作期刊: 《古脊椎动物学报》
摘要： The Early Oligocene is a critical time for global climate changes in the Cenozoic. This epoch witnessed severe mammalian faunal turnovers known as “Grande Coupure” in Europe and “Mongolian Remodelling” in Asia. However, insights about morphological changes in Oligocene mammal lineages have not been explored in detail. One of the least diversified groups of recent mammals, lagomorpha, is globally common in the fossil records, especially in Asia. During the Oligocene, many Eocene archaic lagomorph taxa died out and were replaced by more advanced forms. New findings from Nei Mongol and re-examination of the specimens from older collections enabled a revision of a common Asian lagomorph genus, Ordolagus, which possibly has a close affinity with the Middle–Late Eocene genus Gobiolagus. In Nei Mongol, we recognized the presence of Ordolagus during the basal Early Oligocene. Comparisons with coeval and slightly older lagomorph taxa from Asia and North America show that Ordolagus attained some salient tooth morphological characters (i.e., development of anteroconid on p3, full hypselodonty of cheek teeth, and lingual connection of trigonid and talonid on p4–m2), which are also the key features of modern leporids. The appearance of those morphologic features in Ordolagus is coeval to major global or regional climatic changes. Further investigations on Asian early lagomorphs compared with the study of other small mammals and local climatic factors will be essential to refine the role of lagomorphs as palaeoclimatic proxies.
分类： 生物学 >> 动物学 提交时间： 2021-04-02 合作期刊: 《古脊椎动物学报》
摘要： Here we report a Hipparion fauna locality discovered in between two basalt layers near Hanjiaying Village, Jining District, Wulanchabu City, Nei Mongol. K-Ar isotopic dating of the lower and upper level of the basalt constrains the age of the fauna from 7.2 to 6.8 Ma. Compared with classical Hipparion fauna from northern China, the Hanjiaying fauna is closer to those from Baode of Shanxi, Siziwang Banner of Nei Mongol and the Linxia Basin of Gansu. It is similar to the Loc. 43, 44 and 49 from Baode by faunal composition, confirming their age to be ~7.0 Ma rather than 5.5 Ma. The high similarity with the fossils from Wulanhua, Siziwang Banner, Nei Mongol, verified the age of Wulanhua fauna at about 7 Ma. Compared with faunas from the Linxia Basin, Gansu, it is more similar to those from the upper part of the Liushu Formation, especially the Yangjiashan fauna. Based on the faunal composition and their tooth morphology, the Hanjiaying fauna could be included in the “Gazella dorcadoides” fauna, which is supposed to be at the west paleobiome in northern China during the Late Miocene.
分类： 生物学 >> 动物学 提交时间： 2017-11-07 合作期刊: 《古脊椎动物学报》
摘要： Fossil gazelles have been widely distributed in Eurasia and Africa during the late Neogene. They are key elements of “Hipparion” faunas with prominent biochronologic and ecological significance. However, no pre-Baodean age gazelle previously reported from China. We describe here in detail materials found from the Bahe Formation, Shaanxi Province, which include by far the most complete skulls and postcranials. The first fossil gazelle skeleton is mounted based on the new findings. Morphology and measurements show the similarity with Gazella lydekkeri from Dhok Pathan Formation of middle Siwaliks, different from the most common species G. gaudryi, G. paotehensis, and G. dorcadoides from Baodean age and other gazelles from Europe. Ecomorphology and measurements of long bones indicate the Lantian species, Gazella cf. G. lydekkeri, is possibly a fast runner, adapted to an open environment in Bahean age. The open environment was also suggested by faunal composition, sedimentological analysis and isotope data.
分类： 生物学 >> 动物学 提交时间： 2017-11-07 合作期刊: 《古脊椎动物学报》
摘要： 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.
分类： 生物学 >> 动物学 提交时间： 2017-11-07 合作期刊: 《古脊椎动物学报》
摘要： A unique canal (calcaneal canal) running diagonally through the calcaneus was commonly considered as characteristic for lagomorphs, both extant and fossil, but absent in rodents and other pertinent lagomorph relatives. However, our investigation of a calcaneus from the Middle Paleocene of Qianshan, Anhui Province and specimens previously grouped in Mimotonidae also shows presence of canals on calcaneus bones. To further explore the unique character, we scanned calcanei of Ordolagus, Mimolagus, Gomphos, Rhombomylus, and Oryctolagus using micro CT and investigated the calcanei of some other related taxa under microscope. Three-dimensional reconstructions of the calcanei based on CT data of these taxa confirmed the presence of apertures traversing the large medullary cavity. The diagonally oriented calcaneal canal is present not only in lagomorphs, but also in non-lagomorph duplicidentates, such as Mimotona, Gomophos, and simplicidentates, such as Rhombomylus, though smaller in size. Hence, the presence of calcaneal canal may be one of the synapomophic characters for Glires, not only for the order Lagomorpha. The shared calcaneus character confirms the close relationship between Simplicidentata and Duplicidentata.
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