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1. chinaXiv:202104.00006 [pdf]

Climate change and evolution of early lagomorphs (Mammalia): a study perspective based on new materials of Ordolagus from Nei Mongol (northern China)

Chiara ANGELONE; ZHANG Zhao-Qun
Subjects: Biology >> Zoology

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.

submitted time 2021-04-02 From cooperative journals:《古脊椎动物学报》 Hits189Downloads92 Comment 0

2. chinaXiv:202104.00007 [pdf]

An Upper Miocene “Hipparion fauna” locality sandwiched by basalts in Hanjiaying, Nei Mongol

WANG Qian;LIU Yan;WANG Li-Hua; Mikael FORTELIUS; ZHANG Zhao-Qun
Subjects: Biology >> Zoology

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.

submitted time 2021-04-02 From cooperative journals:《古脊椎动物学报》 Hits124Downloads51 Comment 0

3. chinaXiv:201908.00095 [pdf]

First report of immature feathers in juvenile?enantiornithines from the Early Cretaceous Jehol avifauna

Jingmai K. O’CONNOR; Amanda FALK; WANG Min; ZHENG Xiao-Ting
Subjects: Biology >> Zoology

Molting—the process replacing one plumage with another—is a critically important?biological function in Aves. This process annually replaces the feather coat, damaged by normal?wear and tear, produces ontogenetic changes in feathering, and produces alternate breeding?plumages associated with reproductive activity in adults. Immature, growing feathers are?encased in a keratinous sheath, giving them a narrow, tubular, and featureless appearance. The?complete loss of the sheath indicates the feather is mature. Despite the wealth of integumentary?data published from the Jehol Biota, immature feathers have never been definitively reported,?although they may potentially be preserved in a juvenile specimen of the non-avian oviraptorosaur?theropod dinosaur Similicaudipteryx from the 120 Ma Jiufotang Formation. A developing?feather has been reported in a 99 Ma enantiornithine neonate preserved in Burmese amber, in?which three-dimensional preservation makes interpretations of integumentary structures more?straightforward. Here we report on probable immature feathers in four juvenile enantiornithines?(Aves: Ornithothoraces) from the Jehol Group. As observed in developing feathers in extant?birds, the purported immature fossil feathers appear proximally narrow and featureless with?barbs protruding only distally. Based on our observations, we suggest that similar-appearing?feather structures preserved on the manus and tibiotarsus in the holotype of the enantiornithine?Cruralispennia multidonta may alternatively be interpreted as immature feathers. The presence?of immature feathers in combination with sexually dimorphic ornamental feathers in juvenile?enantiornithines suggests the complex molting patterns of Neornithes, in which such ornaments?only appear after several years (following several molts) when reproductive activity is achieved,?are limited to a subset of crownward avians.

submitted time 2019-08-27 From cooperative journals:《古脊椎动物学报》 Hits7585Downloads946 Comment 0

4. chinaXiv:201908.00119 [pdf]

New gobiconodontid (Eutriconodonta, Mammalia) from?the Lower Cretaceous Shahai and Fuxin formations,?Liaoning, China

KUSUHASHI Nao; WANG Yuan-Qing; ?LI Chuan-Kui; JIN Xun
Subjects: Biology >> Zoology

Eutriconodontans are one of the key members of mammals to our understanding of the evolution and transition of mammalian fauna in Asia during the Cretaceous. Two gobiconodontid?and two triconodontid species have previously been reported from the upper Lower Cretaceous?Shahai and Fuxin formations. Here we describe two additional eutriconodontans from the?formations, Fuxinoconodon changi gen. et sp. nov. and ?Gobiconodontidae gen. et sp. indet.?This new species is attributed to the Gobiconodontidae, characterized by having an enlarged?first lower incisor, reduction in the number of incisors and premolariforms, proportionally large?cusps b and c being well distant from cusp a on the molariforms, presence of a labial cingulid,?and a unique mixed combination of molariform characters seen on either the first or the second,?but not both, generations of molariforms in Gobiconodon. Together with the four known species,?eutriconodontans remained diverse to some extent in the late Early Cretaceous in Asia, although?their family-level and generic level diversity appears to have been already reduced at that time.

submitted time 2019-08-26 From cooperative journals:《古脊椎动物学报》 Hits8480Downloads979 Comment 0

5. chinaXiv:201908.00120 [pdf]

New gobiconodontid (Eutriconodonta, Mammalia) from?the Lower Cretaceous Shahai and Fuxin formations,?Liaoning, China

KUSUHASHI Nao; WANG Yuan-Qing; ?LI Chuan-Kui; JIN Xun
Subjects: Biology >> Zoology

Eutriconodontans are one of the key members of mammals to our understanding of the evolution and transition of mammalian fauna in Asia during the Cretaceous. Two gobiconodontid?and two triconodontid species have previously been reported from the upper Lower Cretaceous?Shahai and Fuxin formations. Here we describe two additional eutriconodontans from the?formations, Fuxinoconodon changi gen. et sp. nov. and ?Gobiconodontidae gen. et sp. indet.?This new species is attributed to the Gobiconodontidae, characterized by having an enlarged?first lower incisor, reduction in the number of incisors and premolariforms, proportionally large?cusps b and c being well distant from cusp a on the molariforms, presence of a labial cingulid,?and a unique mixed combination of molariform characters seen on either the first or the second,?but not both, generations of molariforms in Gobiconodon. Together with the four known species,?eutriconodontans remained diverse to some extent in the late Early Cretaceous in Asia, although?their family-level and generic level diversity appears to have been already reduced at that time.

submitted time 2019-08-26 From cooperative journals:《古脊椎动物学报》 Hits8622Downloads938 Comment 0

6. chinaXiv:201711.01893 [pdf]

Dentition of Subengius mengi (Mammalia: Plesiadapoidea) and a reassessment of the phylogenetic relationships of Asian Carpolestidae

K. Christopher BEARD; NI Xi-Jun; WANG Yuan-Qing; MENG Jin; Daniel L. GEBO
Subjects: Biology >> Zoology

New fossils pertaining to the oldest known Asian plesiadapiform, the Gashatan carpolestid Subengius mengi, clarify aspects of the dental anatomy of this taxon. The dentition of S. mengi is substantially more primitive than previously recognized in retaining a lower dental formula of 2.1.3.3, a low-crowned p4 with three main cusps that are less fully connate than their counterparts in species of Elphidotarsius, P3 with a narrower and structurally simpler lingual margin, and in lacking widely splayed paraconid and metaconid on m1. The unique structure of P3 in S. mengi and a reassessment of P3 anatomy in Elphidotarsius sp., cf. E. florencae, suggest that certain cusp homologies on P3 in Carpolestidae have been misinterpreted in the past. Following a detailed character analysis, the phylogenetic relationships of carpolestids and their close relatives are reconstructed. The Bumbanian taxon Chronolestes simul is recovered as the most basal member of Carpolestidae. S. mengi and a second Bumbanian taxon, Carpocristes oriens, also appear to be relatively basal members of the carpolestid radiation, although none of these Asian carpolestid taxa seems to be specially related to each other. Dispersal of carpolestids between Asia and North America appears to have been restricted to earlier parts of the Paleocene, although carpolestids survived on both continents until sometime near the Paleocene–Eocene boundary.

submitted time 2017-11-07 From cooperative journals:《古脊椎动物学报》 Hits2280Downloads927 Comment 0

7. chinaXiv:201711.01894 [pdf]

The incisor enamel microstructure of Mina hui (Mammalia, Glires) and its implication for the taxonomy of basal Glires

MAO Fang-Yuan; LI Chuan-Kui; WANG Yuan-Qing; LI Qian; MENG Jin
Subjects: Biology >> Zoology

The incisor enamel microstructure of Mina hui Li et al., 2016 from the upper Wanghudun Formation, Middle Paleogene of Qianshan, Anhui is described following the hierarchical system ranging from crystallites to Schmelzmuster. The enamel sample was taken from the upper incisor of the holotype. The enamel consists of a very thin prismless external layer, a relatively thick outer layer (PE) with radial enamel and an inner layer (PI) with multilayered Hunter-Schreger bands (HSB). The thickness of HSB is irregular and the inclination has a small angle; no transition zones between the HSB; prism cross sections are irregularly round; interprismatic matrix is very thick with crystallites in the PE running parallel to the prism long axes. These characters resemble pauciserial HSB in rodents. Ribbon-like prism seams and convergent crystallite discontinuities are consistent in different portions of the enamel, which are interpreted as a primitive feature for Glires, or even placental mammals. Compared with known enamel structure of basal Glires, the enamel of Mina stands for the earliest known evidence of double-layered enamel of the group. It indicates that the early evolution of Glires and placental mammals is complex and adds more details to the enamel microstructure of the earliest Glires.

submitted time 2017-11-07 From cooperative journals:《古脊椎动物学报》 Hits2118Downloads886 Comment 0

8. chinaXiv:201711.01902 [pdf]

Taxonomic revision of lizards from the Paleocene deposits of the Qianshan Basin, Anhui, China

DONG Li-Ping; Susan E. EVANS; WANG Yuan
Subjects: Biology >> Zoology

Although the Late Cretaceous lizard fauna of China and Mongolia is relatively well-known, information on Paleocene lizards from the same region is currently limited. Several species of lizards have been reported from the Paleocene Wanghudun and Doumu formations of Qianshan Basin on the basis of fragmentary specimens, namely Agama sinensis Hou, 1974, Anhuisaurus huainanensis Hou, 1974, Anqingosaurus brevicephalus Hou, 1976, Changjiangosaurus huananensis Hou, 1976, Qianshanosaurus huangpuensis Hou, 1974, and Tinosaurus doumuensis Hou, 1974. In this paper, we review all the reported material of these taxa with the aid of new technology, including CT scanning, and according to current views of squamate relationships and classification. Revised descriptions and classifications are given for each taxon, leading to changes in our understanding of faunal composition. This, in turn, reveals greater morphological and ecological diversity among the Paleocene lizards of the Qianshan Basin, including the occurrence of a varaniform (IVPP V 22767), and the reinterpretation of Anqingosaurus as a possible burrower. Further work on the Paleocene Qianshan lizards is ongoing and the discovery of new specimens may help to solve the puzzles these strange lizards have posed.

submitted time 2017-11-07 From cooperative journals:《古脊椎动物学报》 Hits1312Downloads508 Comment 0

9. chinaXiv:201711.01911 [pdf]

New information on Dianmeisaurus gracilis Shang & Li, 2015

SHANG Qing-Hua; LI Chun; WU Xiao-Chun
Subjects: Biology >> Zoology

Dianmeisaurus gracilis is restudied on the basis of a new specimen. It provides some new information, especially that on the skull roof, to the species. The most striking of those new characters include the snout (preorbital region) shorter than the orbit, the interorbital septum extremely narrow, the frontal with a sharp process at both ends, and the posterior margin of the skull roof deeply V-shaped. A phylogenetic analysis with new information confirms that Dianmeisaurus is the sister group of Diandongosaurus and that these two genera, together with those Chinese taxa (Majiashanosaurus, Dianopachysaurus, Keichousaurus, and Dawazisaurus), form a monophyletic clade which is more closely related to the Nothosauroidea than to a clade formed by the European pachypleurosaurs.

submitted time 2017-11-07 From cooperative journals:《古脊椎动物学报》 Hits1507Downloads668 Comment 0

10. chinaXiv:201711.01916 [pdf]

Early Mammut from the Upper Miocene of northern China, and its implications for the evolution and differentiation of Mammutidae

WANG Shi-Qi; LI Yu; Jaroon DUANGKRAYOM; CHEN Shao-Kun; HE WenCHEN Shan-Qin
Subjects: Biology >> Zoology

Mammut is the terminal taxon of the proboscidean group Mammutidae, which survived to the Late Pleistocene. Although this genus was widely distributed in the Pliocene of Eurasia and the Pleistocene of North America, little is known about its early evolution. Here, we report on Mammut cf. M. obliquelophus from the Upper Miocene of northern China based on new fossil material, including an almost complete juvenile cranium and other remains, which show many primitive features within Mammutidae and clearly demonstrate the morphological evolution of Mammut. The strongly laterally expanded lateral wing of the occiput and the presence of basal constriction of the incisive fossa display cranial similarity between Mammut cf. M. obliquelophus and both Eozygodon morotoensis and Choerolophodon guangheensis, early representatives of the Mammutidae and Choerolophodontidae, respectively, indicating the close relationship between these two groups: both of them are located at the basal phylogenetic positions in Elephantimorpha. This result is further confirmed by a cladistic analysis.

submitted time 2017-11-07 From cooperative journals:《古脊椎动物学报》 Hits1736Downloads982 Comment 0

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