Table of Content

15 December 2009, Volume 47 Issue 4

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FIRST BEAR MATERIAL FROM DONGXIANG, GANSU --- Addition to the Longdan Mammalian Fauna (2)

QIU Zhan-Xiang, DENG Tao, WANG Ban-Yue

2009, 47(4):  245-264. 

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Two bear specimens obtained from Dongxiang area were noticed from the purchased “dragon bones” of the Hezheng Countyin 2006: a complete mandible (HMV 1422) and a skull in association with its mandible (HMV 1454). They represent the first bear material of the Longdan mammalian fauna. Although slightly different in morphology, they are found to be very close to Ursus (Protarctos)yinanensis described by Li Yizheng in 1993, and thus referred to this species. A revised diagnosis of this species is given in the text. Based on high degree of genetic homogeneity and short divergence time of the 6 extant ursine species, molecular and biochemical biologists are being increasingly confident that all the extant ursines should be assigned to a single genus, Ursus. On the other hand, most of the paleontologists, governed by their factual knowledge of morphologic distinctions between these ursine species, are inclined to separate them into different genera. Nevertheless, the Eurasian Pliocene−Early Quaternary bear fossils have often been indiscriminately referred to Ursus. A closer observation of the bear materials during our comparative study of the Dongxiang bear specimens revealed great variety in bear m1 morphology, implying its particular importance in classification of the Ursinae. Based mainly on m1 morphology, coupled with other skull and dental features, the majority of the Eurasian Pliocene−Early Quaternary bears can possibly be divided into three groups: 1) The bears having simple m1’s, lacking pre-metaconids and pre-entoconids, with the transverse groove surfaces being basically smooth. 2) Those having m1’s with pre-metaconids and V-, Y-, or X-shaped ridges on the transverse grooves, but no pre-entoconids. The m1 morphology of this group is close to that of the extant black bears. 3) Those having m1’s with bunodont pre-metaconids, pre-entoconids and well developed accessory cusplets. The m1 morphology of this group is basically that of the extant brown bears. The 1st group includes the specimens from Baróth-Köpecz, Yinan (and Dongxiang), and the left hemimandible of Serrat d’en Vacquer described in 1890. The 2ndgroup includes those from Perrier, Węże, Layna, Wölfershein, etc., and the skull and mandible from Serrat d’en Vacquer described in 1892. The 3rd group includes U. etruscus of many European localities, among which Val d’Arno and St. Vallier are the principal ones. Morphologic distinctions between, and the degree of variability within, these three groups strongly inclined us to separate them into different genera. If the above viewpoint is tenable, three generic names would be suitable for them: Protarctos, Euarctos and Ursus. In this case, Protarctos would include P. boeckhi (MN 14), P.ruscinensis (MN 15) and P. yinanensis (equivalent to MN 16−17).Euarctos would include E. pyrenaicus (MN 15), E. minimus (MN 16−17) and the extant American and Asian black bears. Ursus would contain U. etruscus (MN 17), U. spelaeus etc., and the extant brown bear (and possibly U. maritimus).

Taxonomy and Evolutionary Process of Neogene Bovidae from China

Chen Guan-Fang, Zhang Zhao-Qun

2009, 47(4):  265-281. 

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Bovidae is one of the most diversified groups of Neogene mammals. The study of Chinese Neogene Bovidae traced back to the beginning of the 20th century(Schlosser,1903). During the 1920's and 1930's, Neogene bovid fossil collecting and describing reached a peak. Fromthe 1950's on, not only some new bovid taxa have been reported based on the materials obtained from Northern and Southwest China, but also the systematic positions of some bovid genera have been revised by Chinese paleontologists. In this paper, we try to review the taxonomy based on the most recent progress. Till now, 30 genera belonging to 5 subfamilies of Bovidae have been recognized from Chinese Neogene (Table 1). Most of the genera were found from North China. There discovered few taxa from the Late Miocene of Southwest China. Analysis of the geological and geographical distribution of fossil Bovidae from China shows 5 evolutionary phases and 4 turnovers during the Neogene: Phase 1: Late Oligocene-Early Miocene. Fossil Bovidae is only represented by Sinopalaeoceros Chen,1988(Hypsodontinae). It occurred in the Early Miocene of Qinghai and in the Late Oligocene of Xinjiang. Phase 2: Middle Miocene(Tunggurian). Bovids are characterized by the presence of Turcocerus Kohler,1987 and Kubanotragus Sokolov,1973. They distributed only in North China. Phase 3: Late Miocene(Bahean-Baodean). Bovids are characterized by the flourishing of Urmiatherini, and a specialized group belonging to Caprinae. Gazella(Antilopinae) is also one of the most common genera. Phase 4: Early Pliocene. The dominant elements are Gazella and endemic forms of Caprinae. Phase 5 Late Pliocene. Bovids are characterized by the occurrence of extant genera and species,e.g. Ovis and Gazella subgutturosa. These phases also indicate 4 turnover events of bovid faunas during the Neogene. The first turnover event happened after the first phase, in between the Early and Middle Miocene. Sinopalaeoceros went extinct, and there occurred Turcocerus, which is the dominant element during the Middle Miocene in North China. The Middle Miocene/Late Miocene boundary witnessed the second remarkable turnover event of Bovidae. None of the Middle Miocene taxa survived into the Late Miocene. The third turnover event happened near the Miocene/Pliocene boundary. The diversified group Urmiatheriini went extinct. The fourth turnover event is characterized by the occurrence of extant genera and species during and after the Late Pliocene.

Late Cenozoic environmental changes in the Linxia Basin (Gansu, China) as indicated by cenograms of fossil mammals

DENG Tao

2009, 47(4):  282-298. 

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The evolutionary history of mammalian communities is significant for reconstructing past environments and climate. A cenogram is a rank-ordered body mass distribution of non-predatory terrestrial mammal species within a fauna. Based on comparisons with modern faunas, cenograms of fossil faunas have been used for inferring environments and their changes through geological time. In this paper, an environmental reconstruction based on the Late Cenozoic mammalian faunas of the Linxia Basin (Gansu, China), ranging in age from the Late Oligocene to the Early Pleistocene, is presented using the cenogram method. Body sizes for fossil taxa were estimated using regressions of body weight based on the area of the first lower molar for most species and on other teeth or limb bones for a few species. Most measurements for the body estimations are from the Linxia fossils, while a few are from the literature. Cenogram statistics are calculated for seven fossil faunas, allowing paleoenvironmental interpretations to be made. These analyses reveal open conditions during the Late Miocene, Early Pliocene and Early Pleistocene; less open conditions during the Late Oligocene but a closed environment during the Middle Miocene; arid conditions during the Late Oligocene and earliest Late Miocene; less arid during the Late Miocene, Early Pliocene, and Early Pleistocene but humid during the Middle Miocene.

A NEW BASAL ORNITHURINE BIRD (JIANCHANGORNIS MICRODONTA GEN. ET SP. NOV.) FROM THE LOWER CRETACEOUS OF CHINA

ZHOU Zhong-He, ZHANG Fu-Cheng, LI Zhi-Heng

2009, 47(4):  299-310. 

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A new genus and species of a basal ornithurine bird is reported from the Lower Cretaceous Jiufotang Formation of Jianchang, Liaoning, China. It is represented by a nearly complete articulated skeleton of a sub-adult individual. It is distinguishable from other known ornithurines by possessing a combination of features including at least 16 small and conical teeth on the dentary, scapula strongly curved, metacarpal I robust and wider than other metacarpals, first manual digit long and extending beyond distal metacarpal II, and length ratio of humerus+ulna+metacarpal II to femur+tibiotarsus+tarsometatarsus is approximately 1.1. Phylogenetic analysis indicates that the the new taxon is a basal ornithurine.Jianchangornis represents the second Early Cretaceous bird with the preservation of a predentary bone, which may further confirm that a predentary could be a feature common to Mesozoic ornithurines. The advanced features of the pectoral girdle, sternum and wings of the new bird indicate its powerful flight capability, and the hindlimb bone and toe proportions as well as the ungual morphology suggest a terrestrial locomotion similar to those of Yanornis and Yixianornis. The associated fish fragments may indicate a piscivorous diet consistent with the dentation of the new bird. The discovery of a new basal ornithurine further shows that the diversification of the Ornithurae is probably no less than the enantiornithes, and the near lakeshore adaptation had definitely played a key role in the early ornithurine radiation.

THE ORIGIN AND EARLY EVOLUTION OF FEATHERS: INSIGHTS FROM RECENT PALEONTOLOGICAL AND NEONTOLOGICAL DATA

XU Xing, GUO Yu

2009, 47(4):  311-329. 

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Recent paleontological and neontological studies on feathers and feather-like integumentary structures have improved greatly our understanding of the origin and early evolution of feathers. New observations on some non-avian dinosaur specimens preserving integumentary structures, in combination with recent paleontological and neontological data, provide additional insights into this important evolutionary issue. Five major morphogenesis events are inferred to have occurred sequentially early in feather evolution before the origin of the Aves, and they are: 1) appearance of filamentous and tubular morphology, 2) formation of follicle and barb ridges, 3) appearance of rachis, 4) appearance of planar form, and 5) formation of pennaceous barbules. These events produce several morphotypes of feathers that are common among non-avian archosaurs but are probably lost later in avian evolution, and they also produced several morphotypes of feathers that are nearly identical or identical to those of modern birds. While feathers of non-avian dinosaurs exhibit many unique features of modern feathers, some of them also possess striking features unknown in modern feathers. Several models of evolutionary origin of feathers based on developmental data suggest that the origin of feathers is a completely innovative event and the first feathers have nothing to do with reptilian scales. We believe, however, that the defining features of modern feathers might have evolved in an incremental manner rather than in a sudden way. Consequently, an evolutionary model characteristic of both transformation and innovation is more acceptable for feather evolution. The function of the first feather is inferred to be neither related to flight nor to insulation. Display or heat dissipation, among others, remains viable hypotheses for initial function of feathers. An integrative study is promising to provide much new insights into the origin of feathers.