Subjects: Biology >> Biological Evolution submitted time 2024-03-20
Abstract： Here we report a new form of amphicyonid from an uncertain locality in the Linxia Basin. The derived dental traits imply an affinity to Magericyon, previously known from Europe and possibly southern Asia. The specimen suggests a higher diversity of amphicyonids in eastern Asia than previously thought, and more discovery with stratigraphic information will be needed to elucidate the evolution of Amphicyonidae in eastern Asia.
Subjects: Biology >> Zoology submitted time 2024-01-28 Cooperative journals: 《古脊椎动物学报》
Abstract： As a small to middle-sized bovid, Hispanodorcas had previously only been found in the pan-Mediterranean region and South Asia. Its taxonomic classification at the tribe level has been a subject of debate, with possible associations to Antilopini, Reduncini, or Oiocerini. Here, we report on the first discovery of Hispanodorcas in East Asia, H. longdongica sp. nov. from the Daidian Locality in China, dating to the early Baodean age (~8–7 Ma). The new material consists of five skulls with varying states of preservation and provides the most complete osteological information on Hispanodorcas to date. It features a long, slender, and posteriorly curved horncore with a weak homonymous twist and both laterodorsal and medioventral grooves, which is characteristic of Hispanodorcas. This new species is characterized by having the smallest size amongst all known Hispanodorcas species, a weakly curved brain case in the facial region, and poorly developed posterior and anterior basilar tuberosities. These primitive characteristics suggest that H. longdongica may represent an early evolutionary stage of this genus. Furthermore, they indicate that Hispanodorcas might have directly evolved from the Gazella stock. The homonymous twist in the horncore, which aligns with Oiocerini, may be a case of homoplasy.
Subjects: Biology >> Zoology submitted time 2023-09-20 Cooperative journals: 《古脊椎动物学报》
Abstract： Trilophodon connexus Hopwood, 1935 has long been considered a typical species of Gomphotherium in China. However, due to the unknown state of the mandibular symphysis and tusks, there is no definite evidence to assign “T. connexus” to Gomphotherium. Here we describe and reevaluate a hemimandible from the Halamagai Formation, Ulungur region, northern Junggar Basin, which was previously identified as Gomphotherium cf. G. shensiensis. The mandibular symphysis is deeply troughed and lacks mandibular tusks; therefore, it undoubtedly belongs to the Choerolophodontidae. Further comparison revealed that the cheek tooth morphology is identical to that of the type specimen of Trilophodon connexus. The characteristic features include high bunodonty, elongation of the m3 with four lophids, an only weakly chevroned lophid 2, enlargement of the posterior pretrite central conule 2, unfused state of the pretrite mesoconelet 2 (if present) and anterior pretrite central conule 2, as well as the absence of ptychodonty, choerodonty, and cementodonty. Therefore, T. connexus Hopwood, 1935 is a choerolophodontid rather than a species of Gomphotherium. Based on the above features, we provisionally refer to it as “Choerolophodon” connexus. “Choerolophodon” connexus is characterized by the following features: weak or absent ptychodonty, choerodonty, and loph chevron (which were all strong in the typical species of Choerolophodon), as well as multiplication of the lophids in the m3, which were similar to that of the North American Gnathabelodon. Therefore, Gnathabelodon might represent a distinct lineage within the Choerolophodontidae, and may be derived from the East Asian “Choerolophodon” connexus.
Subjects: Biology >> Zoology submitted time 2023-03-14 Cooperative journals: 《古脊椎动物学报》
Abstract： The zygodont proboscideans from the Miocene strata of China are widely distributed. However, the materials are scarce, and their classification has experienced a longtime controversy, from the chaotic state of multiple Zygolophodon species to the only one species, Zygolophodon gobiensis. The combined species Z. gobiensis comprises both the gracile type with a high degree of zygodonty and the robust type that is between the typical bunodont and zygodont morphology. Recently, as the robust type has been re-allocated to another genus Miomastodon and new fossil remains were discovered, it is necessary to further evaluate and classify the zygodont proboscideans from the Miocene of China. In the present paper, we restudied the previously published zygodont specimens of the gracile type, as well as several unpublished Mammutidae specimens. The former including Z. nemonguensis, Z. gromovae, Z. jiningensis, Z. chinjiensis and two specimens of Gomphotherium xiaolongtanensis, represents Zygolophodon in the original sense in China. In these specimens, the tip of the loph(ids) are sharp. The anterior and posterior pretrite central conules are absent or very weak, and the anterior and posterior crescentoids are sharp and slender. The posttrite mesoconelets are well subdivided and the zygodont crests are developed. In buccal view, the loph(id)s are “Ʌ-shaped” and the interloph(id) s are “V-shaped”. Their molar morphology resembles that of Z. turicensis, and hereby, they were identified as Zygolophodon cf. Z. turicensis. Several unpublished specimens from Hezheng, Gansu, Tunggur, Nei Mongol, Tongxin, Ningxia and Junggar, Xinjiang exhibit a lower degree of zygodonty, corresponding to the “robust type of Zygolophodon” in which the molar morphology is between the typical bunodonts and zygodonts. The pretrite crescentoids are thicker than Zygolophodon cf. Z. turicensis, and the pretrite central conules usually present on the first and second interloph(id)s. According to the stratigraphic age and characteristics, two species, Miomastodon gobiensis and Mio. tongxinensis were identified. The anterior and posterior pretrite crescentoids of Mio. tongxinensis are weaker and the pretrite central conules are larger than Mio.gobiensis. Geographical distribution indicates that Miomastodon is the predominant member of zygolophodonts in the Early and Middle Miocene in northern China. The discovery of new materials and the reclassification of zygolophodonts provide further evidence for dispersal of Mammutidae from Eurasia to North America and the evolutionary relationships among the species of the family Mammutidae in China.
Subjects: Biology >> Zoology submitted time 2022-04-16 Cooperative journals: 《古脊椎动物学报》
Abstract： Platybelodon is the predominant proboscidean of northern China’s Middle Miocene. However, the cranial and cheek tooth morphologies are not clearly diagnosed. In particular, the differential diagnoses between Platybelodon and Gomphotherium have not been comprehensively examined. Here we restudied the cranium previously identified as Gomphotherium shensiense. The upper tusks lack an enamel band, the rostrum is long and narrow, the facial part is rostrally positioned, and a large “prenasal slope” is present. These characters are distinct from those of any species of Gomphotherium, but fit well with some primitive species of Platybelodon, i.e., P. tongxinensis and P. danovi. The molars are also close to the type specimen of P. tongxinensis in the tetralophodont M3 with mesiodistally wide interlophs, curved outline, and a tendency of cementodonty. In this article, we synonymized Gomphotherium shensiense with P. tongxinensis. Moreover, we recognized a new species, Platybelodon tetralophus, from the P. grangeri material collected by the AMHN expedition in Tunggur region. Platybelodon tetralophus differs from P. grangeri and the other species in the tetralophodont M2 and m2, representing the most derived species within Platybelodon. It has only occurred in the uppermost horizon of the Tunggur Formation, i.e., the Tamuqin Fauna (Platybelodon Quarry and Wolf Camp Quarry of AMHN). This work is a comprehensive amending of the genus Platybelodon.
Subjects: Biology >> Zoology submitted time 2021-07-30 Cooperative journals: 《古脊椎动物学报》
Abstract： The mastodont-grade proboscideans represent an important stage in the evolution of the group, establishing the basic pattern of the evolution of the crown groups of proboscideans. The research on mastodons has a history of more than 400 years. The classification and nomenclature have been revised and changed many times, and the problems in their evolution were fully reflected in the history of mastodon nomenclature. In this paper, we undertook a bibliographical research into the nomenclature and etymology of various mastodont groups, reviewing 175 translated Chinese names of mastodont-grade proboscideans, including 12 taxon names higher than the genus level, 46 genera, and 117 species, covering almost all the species of the mastodont radiation. On this basis, we review the principal phylogenetic hypotheses of mastodont interrelationships, and highlight problems in the classification and nomenclature of mastodonts. The evolution of the skull and mandible of mastodons is continuous in all clades, reflecting the same parallel evolution trend; while, although the morphological characteristics of cheek teeth across all lineages are not obvious, they are relatively stable in each lineage. Choerolophodontidae is the most robust monophyletic group within the mastodonts, of which Synconolophus may be a distinct, valid genus. Miomastodon and Pliomastodon of Mammutidae may both be valid, but they are not necessarily the direct ancestor of Mammut americanum. The phylogenetic relationship between Platybelodon danovi, P. grangeri and Aphanobelodon zhaoi within the Amebelodontidae is questionable, depending on whether the lower incisor section of P. danovi is the dentine rod structure or not, while Konobelodon britti in America may be a synonym of Torynobelodon loomisi. The species assigned to Konobelodon in Asia is possibly not amebelodontids, but probably attributable to Paratetralophodon, instead; Serridentinus of Gomphotheriidae may be a valid taxon, representing a trend towards somewhat zygodonty in Gomphotheriidae that terminated with the Cuvieroniinae. The Cuvieroniinae may only include Cuvieronius and Rhynchotherium, while other brevirostrine gomphotheres in America, such as Stegomastodon may have been evolved from a lineage of amebelodonts. Notiomastodon may be related to Sinomastodon, which itself may have originated from Pliomastodon (?) zhupengensis in southern China. The name Mastodon intermedius Teilhard de Chardin & Trassaert, 1937 (now Sinomastoodon intermedius) has the senior primary homonym Mastodon intermedius Eichwald, 1831. We suggest that Sinomastodon intermedius should be replaced with its senior synonym– Sinomastodon sendaicus (Matsumoto, 1924).
Subjects: Biology >> Zoology submitted time 2020-03-31 Cooperative journals: 《古脊椎动物学报》
Abstract： The elephantimorph proboscideans, Serridentinus gobiensis Osborn & Granger, 1932, and Miomastodon tongxinensis Chen, 1978, from the Middle Miocene of northern China, were revised as Zygolophodon gobiensis (Osborn & Granger, 1932). However, their phylogenetic positions are still being debated because of their intermediate morphology between the typical bunodont (Gomphotheriidae) and zygodont (Mammutidae) elephantimorphs. In the present paper, we compare their dental and mandibular morphology with that of the Eurasian Z. turicensis, Gomphotherium subtapiroideum, and G. tassyi, as well as the North American Mio. merriami and G. productum. It appears that S. gobiensis and Mio. tongxinensis share with Mio. merriami the slightly more bunodont molar morphology than that of Z. turicensis, e.g., the thicker enamel, thicker pretrite crescentoids, higher interlophid enamel pillars in buccal view, and the narrower contour majorly caused by the narrower posttrite half loph(id)s. S. gobiensis and Mio. merriami also possess an “erected oval cross-sectioned mandibular tusk”, in which the cross-section is mediolaterally compressed (dorsoventral diameter being larger than the mediolateral one). Whereas, in Z. turicensis and G. productum, the mandibular tusk is “laid oval cross-sectioned”, in which the cross-section is dorsoventrally compressed (dorsoventral diameter is smaller than the mediolateral one). Therefore, it is reasonable to revive the genus Miomastodon Osborn, 1922, which contains the species that were previously attributed to Zygolophodon, but they have relatively bunodont molar morphology (i.e., the robust type of the Z. turicensis group). The mandibular tusk with erected oval cross-section seems to be a synapomorphy of Miomastodon species. Furthermore, the molar morphology of G. subtapiroideum and G. tassyi also exhibits intermediate status between the typical bunodonts and zygodonts. However, the mandibular symphysis of G. subtapiroideum and G. tassyi is stronger than that of Miomastodon, and the mandibular tusk is pyriform cross-sectioned. The validity of Miomastodon and G. subtapiroideum/tassyi obscures the boundary between the Gomphotheriidae and Mammutidae, and suggests that the evolutions of the Gomphotheriidae and Mammutidae are deeply involved in with each other, rather than straightforwardly detached. This phenomenon has been revealed by a collagen sequence analysis among Notiomastodon, Mammut, and extant elephants, which should be further studied.
Subjects: Biology >> Zoology submitted time 2017-11-07 Cooperative journals: 《古脊椎动物学报》
Abstract： 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.
Subjects: Biology >> Zoology submitted time 2017-11-07 Cooperative journals: 《古脊椎动物学报》
Abstract： 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.
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