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1. chinaXiv:202105.00071 [pdf]

Using Bayesian tip-dating method to estimate divergence times and evolutionary rates

ZHANG Chi
Subjects: Biology >> Zoology

贝叶斯支端定年法是近些年开发的推断类群分异时间和演化速率的方法。它克服了传统分步计算的缺陷,但涉及到的统计学知识也更多。本文从贝叶斯统计计算的角度分层剖析了支端定年法的原理和计算过程,按照分异时间的先验分布、演化速率的先验分布、特征状态变化的模型和马氏链蒙特卡罗算法几个部分,叙述并讨论了定年计算中的主要模型和算法。旨在一定程度上为古生物学家分析实际数据提供参考。

submitted time 2021-05-20 From cooperative journals:《古脊椎动物学报》 Hits773Downloads211 Comment 0

2. chinaXiv:202105.00073 [pdf]

A new species of Pteronisculus from the Middle Triassic (Anisian) of Luoping, Yunnan, China, and phylogenetic relationships of early actinopterygian fishes

REN Yi; XU Guang-Hui
Subjects: Biology >> Zoology

Actinopterygii, the largest group of extant vertebrates, includes Cladistia, Actinopteri (Chondrostei plus Neopterygii) and closely related fossil taxa. The extinct genus Pteronisculus belongs to a stem lineage of actinopterygian fishes represented by 11 species from the Early Triassic of Madagascar, Europe and North America, and a single species from the early Middle Triassic of China. Here, we report the discovery of a new species of this genus, Pteronisculus changae, on the basis of five well-preserved specimens from the Middle Triassic (Anisian) marine deposits exposed in Luoping, eastern Yunnan, China. The discovery documents the second convincing species of Pteronisculus in the Middle Triassic and the largest stem actinopterygian fish in the Luoping Biota, having a maximum total length of up to 295 mm. The new species possesses a toothed lacrimal, which is characteristic of Pteronisculus, but it is easily distinguished from other species of the genus by some autapomorphies, e.g., a medial process at the middle portion of the intertemporal, 21 supraneurals, and 83 lateral line scales. The results of our cladistic analysis provide new insights into the relationships of early actinopterygians and recover Pteronisculus as a sister taxon of the Carboniferous rhadinichthyid Cyranorhis at the actinopterygian stem. Based on the body form, teeth and other features, it can be deduced that Pteronisculus changae is likely a relatively fast-swimming predator, feeding on planktonic invertebrates and smaller or younger fishes known to occur in the same biota. As one of the youngest species of the genus, the new species provides additional evidence to suggest that the diversity of Pteronisculus is higher than previously thought and that the eastern Paleotethys Ocean likely constituted a refuge for species of this genus during the early Middle Triassic.

submitted time 2021-05-20 From cooperative journals:《古脊椎动物学报》 Hits623Downloads138 Comment 0

3. chinaXiv:202104.00005 [pdf]

Taxonomic revision of the holotype of Proboselaphus watasei Matsumoto, 1915 (Bovidae, Artiodactyla) from Chuanyu area, China

NISHIOKA Yuichiro; KOHNO Naoki; KUDO Yuichiro
Subjects: Biology >> Zoology

A taxonomic revision of Proboselaphus watasei Matsumoto, 1915 (Bovidae, Artiodactyla) from the Pleistocene of Chuanyu area, China demonstrates that this genus and species names are invalid. The holotype with a skull and mandibles was recently rediscovered in the fossil collection by Nobuo Naora, which is housed in the National Museum of Japanese History, Chiba Prefecture, Japan. Proboselaphus watasei was described as a closely-related species to living nilgai, or Boselaphus tragocamelus, in South Asia, based on general characteristics of pecorans, such as small bony horn-cores and hypsodont cheek teeth. However, the cranial and dental morphologies re-examined in the present study clearly show that the holotype has cervid-specific characteristics: e.g., the fronto-parietal surface curving dorsally, the basioccipital with a triangular outline, and molars with isolated anterior and posterior lobes. The molars of the holotype are comparable to those of Cervus unicolor, in having strong accessary structures (or spurs, cingulums/cingulids, and styles/stylids), and are as large as those of Cervus cf. C. unicolor from the Pleistocene deposits in southern China. This taxonomic change suggests that any crown-boselaphins had not dispersed into East Asia since the Pleistocene.

submitted time 2021-04-02 From cooperative journals:《古脊椎动物学报》 Hits1059Downloads309 Comment 0

4. 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》 Hits970Downloads322 Comment 0

5. 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》 Hits906Downloads261 Comment 0

6. chinaXiv:202009.00049 [pdf]

New fossils of Late Pleistocene Sus scrofa from Yangjiawan Cave 2, Jiangxi, China

SUN Ji-Jia; ZHANG Bei; CHEN Xi; DENG Li; ?WEN Jun; TONG Hao-Wen
Subjects: Biology >> Zoology

The YJW (Yangjiawan) Cave 2 of Pingxiang in Jiangxi Province is a karst cave that?developed in the Permian limestone of the Changxing Formation, which is filled with clay and?grit of Late Pleistocene age. Six excavations have been conducted at the site since 2015. More?than ten thousand mammalian fossils have been unearthed, and the wild boar fossils account for?approximately 49%, which represents the richest wild boar fossil tooth collection of Pleistocene?age in southern China. This study focuses on the studies of the canine teeth and the third molars,?and mainly compares fossils of Sus peii and S. xiaozhu in South China and the data of extant S.?scrofa respectively in dental morphology and odontometric data analyses which includes scatter?plot analysis, regression analysis, coefficient of variation analysis and linear discriminant analysis.?The typical scrofic type of the male’s lower canine teeth confirmed the identification of the suid?fossils from YJW Cave 2 as S. scrofa. Although the male’s lower canines, the M2s and m3s,?are among the most variable teeth in sizes, they stay in the ranges of S. scrofa; furthermore, the?scatterplots of both the upper and lower third molars form two distinct clusters respectively, which?can probably be attributed to sexual dimorphism rather than resulting from a mixture of different?suid species. The post-Early Pleistocene suid fauna in southern China is almost only composed of?S. scrofa, which is quite different from the adjacent Southeast Asia where the suid fauna is quite?taxonomically diversified and dominated by the verrucosic type.

submitted time 2020-09-15 From cooperative journals:《古脊椎动物学报》 Hits5823Downloads831 Comment 0

7. chinaXiv:202009.00050 [pdf]

Late Miocene micromammalian assemblage of Tuchengzi and its biochronological position in Neogene faunal sequence in central Nei Mongol, China

ZHANG Li-Min; DONG Wei; Ni Xi-Jun; LI Qiang
Subjects: Biology >> Zoology

Neogene strata rich in fossil mammals are well exposed in central Nei Mongol, China. Over a dozen mammalian faunas in chronological succession from Early Miocene to Early Pliocene were discerned in this region, and they built a fundamental part of the Neogene land mammal biochronological system in northern China. Tuchengzi was first recognized for producing abundant mammalian fossils during the Sino-Soviet Paleontological Expedition (SSPE) initiated in 1959. However, all unearthed fossils from the SSPE were either large- or middle-sized mammals, and small mammal fossils in the Tuchengzi Fauna were deficient for a long time. The composition and biochronological position of the Tuchengzi Fauna in the Neogene mammalian biochronological system in northern China was not particularly clear. The new fossils here reported are represented by 6 taxa of small mammals. Based on the co-occurrence of Lophocricetus grabaui, Sinocricetus zdanskyi, Prosiphneus licenti, Hansdebruijnia pusilla, and Moschus grandaevus, the age of the Tuchengzi Fauna is constrained to late Late Miocene or Baodean Chinese Land Mammal Age, slighter younger than the Baogeda Ula Fauna and older than the Ertemte Fauna. Judging from the fossil composition, the Tuchengzi Fauna possibly inhabited a forest-steppe mixed habitat during the late Late Miocene.

submitted time 2020-09-15 From cooperative journals:《古脊椎动物学报》 Hits6288Downloads892 Comment 0

8. chinaXiv:202008.00033 [pdf]

Taxonomic revision of Anthracokeryx thailandicus ?Ducrocq, 1999 (Anthracotheriidae, Microbunodontinae)?from the Upper Eocene of Thailand

DUCROCQ Stéphane
Subjects: Biology >> Zoology

The anthracotheriid (Mammalia, Cetartiodactyla) species Anthracokeryx thailandicus from the Upper Eocene of Thailand is redescribed in details and a revision of its phylogenetic position within the family is proposed. A combination of important dental differences has been observed that led to attribute the Thai form to a distinct genus, Geniokeryx gen. nov., which represents the third genus included into the Microbunodontinae. The new genus is characterized mainly by its unfused short and deep mandibular symphysis, massive lower and upper premolars, weakly selenodont upper molars that exhibit a protostyle and lack an ectometacristule. The peculiar morphology of its symphysis might have been a sexually dimorphic feature that provided the role of a lateral protection for the enlarged upper canine in males as seen in some Paleogene nimravid carnivorans like Eusmilus. A short review of some Anthracokeryx species from China suggest that A. dawsoni might be synonymous to A. sinensis.

submitted time 2020-08-02 From cooperative journals:《古脊椎动物学报》 Hits8209Downloads811 Comment 0

9. chinaXiv:202008.00034 [pdf]

Additional tsaganomyid, cylindrodontid and?ctenodactyloid rodent materials from the Erden Obo?section, Erlian Basin (Nei Mongol, China)

LI Qian
Subjects: Biology >> Zoology

To improve the Paleogene biochronological framework of the Erlian Basin, Nei Mongol?and clarify the diversity of fossil rodents in this region, new tsaganomyids (Cyclomylus lohensis,Coelodontomys asiaticus) from the “Upper White” beds, cylindrodontids (Gobiocylindrodon sp.,Proardynomys sp., and Cylindrodontidae gen. et sp. indet.) from the “Middle Red” and “Lower?Red” beds, and ctenodactyloids (Yuomys sp.) from the “Lower White” beds of the Erden Obo?section are reported. The appearance of C. lohensis and Co. asiaticus from the Erden Obo section?confirms that the age of the “Upper White” beds is Early Oligocene. The “Upper White” beds?of the Erden Obo section and the top bed of the Nom Khong Obo are confirmed to belong to the?same formation by both lithofacies and mammalian fossils. The different kinds of cylindrodontids?found from the different horizons of the Erden Obo section show that the cylindrodontids had a?high diversity and a relative continuous evolution in Eocene Asia.

submitted time 2020-08-02 From cooperative journals:《古脊椎动物学报》 Hits8148Downloads947 Comment 0

10. chinaXiv:202008.00035 [pdf]

A new species of Luganoia (Luganoiidae, Neopterygii) from the Middle Triassic Xingyi Biota, Guizhou, China

XU Guang-Hui
Subjects: Biology >> Zoology

新鳍鱼类是辐鳍鱼亚纲中最大的现生类群,中三叠世卢加诺鱼科则是新鳍鱼类干群中的一支,具有特化的头骨和特别高的侧腹鳞片。自1939年命名以来,卢加诺鱼科仅以瑞士东部和南部、意大利北部和西班牙东南部中三叠世海相地层安尼期/拉丁期界线附近发现的瓷鳞卢加诺鱼(Luganoia lepidosteoides)为唯一代表。根据贵州兴义中三叠世晚期(拉丁期)海相地层发现的一块较完整的精美鱼化石,命名了卢加诺鱼属一新种,祥瑞卢加诺鱼(Luganoia fortuna sp. nov.)。新种代表了卢加诺鱼科在亚洲的首次出现,表明此科的生物地理分布比之前认识的要大很多。基于新种与模式种的比较研究,修订了卢加诺鱼属的鉴定特征,揭示了该属过去一些未注意到的解剖学特征,例如存在一对眶前骨,缺少板片状的方颧骨,背鳍基部具有一狭长的裸露身体区域;臀鳍很小,与尾鳍的距离比与腹鳍更近;后匙骨缺失。此外,详细列举了中国新种与欧洲模式种的形态差异,研究结果为了解卢加诺鱼属的形态多样性提供了重要信息。

submitted time 2020-08-02 From cooperative journals:《古脊椎动物学报》 Hits8203Downloads939 Comment 0

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