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    A new specimen of Parabohaiornis martini (Avialae: Enantiornithes) sheds light on early avian skull evolution
    WANG Min
    Vertebrata Palasiatica    2023, 61 (2): 90-107.   DOI: 10.19615/j.cnki.2096-9899.230217
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    The Enantiornithes is the most speciose clade of Mesozoic avialans with over 60 named taxa reported from most continents that span the whole Cretaceous. Most of the fossil remains of this clade, as well as those of other early diverging avialans are preserved in two-dimensions. This complicates efforts to extract detailed anatomical information from the skull, in which the composite elements are delicate and thus not easily observable through conventional methods. The scarcity of well-preserved early avialan skulls, as well as the limited number of specimens that have been analyzed using computed tomography scanning, consequently circumscribes a large morphological gap in the fossil record during the transition from the heavy and akinetic dinosaurian skull to the lightweight and kinetic bird skull. Here, we present a three-dimensional digital reconstruction of the skull and part of the cervical vertebrae of a new specimen of the enantiornithine Parabohaiornis martini from the Early Cretaceous of China. Our results demonstrate that Parabohaiornis retains the plesiomorphic non-avialan dinosaurian temporal and palatal configurations, reinforcing the recent hypothesis that the temporal and palatal regions are evolutionarily conservative and that the akinetic skull has been conserved well into diversification of early branching avialans.

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    Taxonomic revision of Sinoeugnathus kueichowensis (Halecomorphi, Holostei) from the Middle Triassic of Guizhou and Yunnan, China
    FENG Dong-Hao, XU Guang-Hui, MA Xin-Ying, REN Yi
    Vertebrata Palasiatica    2023, 61 (3): 161-181.   DOI: 10.19615/j.cnki.2096-9899.230703
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    The previously alleged ‘eugnathid amiiform’ Sinoeugnathus kueichowensis is a small-sized halecomorph from the Middle Triassic (Ladinian) marine deposits of Guizhou and Yunnan, China. A morphological redescription and taxonomic revision of this taxon are provided based on a detailed examination of the holotype and 15 new specimens. Studies of these specimens revealed some morphological details previously undescribed or misidentified for this taxon, including a hatchet-shaped antorbital, two broad suborbitals, a sensory canal in the maxilla, and three pairs of extrascapulars. For the first time, Sinoeugnathus was incorporated into an analysis of halecomorph phylogeny, and the results recover it as the sister taxon of the Anisian Subortichthys from Luoping, Yunnan, and both are grouped with two Ladinian genera Allolepidotus and Eoeugnathus from the Monte San Giorgio area into a monophyletic group (namely Subortichthyidae fam. nov. herein) at the base of Ionoscopiformes. This taxonomic reassessment of Subortichthys provides new insights into the phylogeny and paleogeographic evolution of Ionoscopiformes.

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    The pelvic morphology of Parayunnanolepis (Placodermi, Antiarcha) revealed by tomographic data
    ZHU You-An, WANG Ya-Jing, QU Qing-Ming, LU Jing, ZHU Min
    Vertebrata Palasiatica    2023, 61 (2): 81-89.   DOI: 10.19615/j.cnki.2096-9899.221126
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    The pelvic morphology, and whether the pelvic fin is present or absent in the earliest jawed vertebrates are key in interpreting the origin of vertebrate paired fins. Parayunnanolepis xitunensis, an antiarch placoderm from the Early Devonian of Yunnan, South China, was previously described to possess the earliest evidence of both dermal and endoskeletal pelvic girdles, presumably for the attachment of the pelvic fins. Here, we redescribe the pelvic region of the holotype based on high-resolution computed tomographic data. Instead of having two large plates previously designated as dermal pelvic girdles, Parayunnanolepis possesses three pairs of lateral pelvic plates, and one large oval median pelvic plate. The paired pelvic plates are flat ventral plates, and differ from other dermal pelvic girdles in lacking a dorsal extension. There is no definitive evidence for the presence of an endoskeletal pelvic girdle in Parayunnanolepis, although the possibility cannot be ruled out. A comparison of the dermal pelvic plates in various jawed stem-gnathostomes suggests the presence of both paired and median pelvic plates is shared by different lineages and might be plesiomorphic. The jawed stem-gnathostomes may have recruited the ventral dermal skeleton of the post-thoracic body into different functional units.

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    A small-sized dinocephalosaurid archosauromorph from the Middle Triassic of Yunnan, southwestern China
    WANG Wei, LEI Hong, LI Chun
    Vertebrata Palasiatica    2024, 62 (1): 13-32.   DOI: 10.19615/j.cnki.2096-9899.231013
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    Among numerous marine reptiles discovered in the Triassic eastern Tethys, today’s Southern China, Dinocephalosaurus is a bizarre animal comparable to European Tanystropheus in developing a prominently long neck. These two taxa are respectively assigned to Dinocephalosauridae and Tanystropheidae, and the two families and other basal members collectively form an early-diverging clade of Archosauromorpha. Here we report a new archosauromorph specimen, IVPP V18579, excavated from the lower Middle Triassic (Anisian), from Luoping, Yunnan in southwestern China. Compared with all the hitherto known dinocephalosaurids and tanystropheids, this skeletally mature individual is exclusively similar to Dinocephalosaurus in a number of characteristics, particularly with the long posterodorsal process of the premaxilla extending posteriorly beyond the level of the external nares, the concave posterior margin of the anteroposteriorly broad quadrate, and the strongly expanded distal end of the chevron in most of the caudal vertebrae. However, this reptile is much smaller than Dinocephalosaurus and different from Dinocephalosaurus and the other dinocephalosaurid, Pectodens, in many aspects, such as an anteriorly tapering long rostrum, the dentition composed of short conical teeth with less heterodonty, relatively but obviously tall neural spines of the axis and the anterior cervical vertebrae. Our phylogenetic analysis suggests that the new archosauromorph is a dinocephalosaurid, and then we erect Austronaga minuta gen. et sp. nov. based on this specimen. Detailed comparisons in osteological anatomy and the discussion about its potential aquatic adaptation of this new taxon are also provided.

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    New zygolophodonts from Miocene of China and their taxonomy
    ZHANG Xiao-Xiao, YANG Xu, SUN Yan, WANG Hong-Jiang, YANG Rong, CHEN Shan-Qin, WANG Shi-Qi, LI Hong
    Vertebrata Palasiatica    2023, 61 (2): 142-160.   DOI: 10.19615/j.cnki.2096-9899.230308
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    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.

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    Mansancun Micromammal Fauna from the upper part of the Jiaozigou Formation in Linxia Basin, Gansu Province
    WANG Ban-Yue, QIU Zhan-Xiang, WANG Shi-Qi
    Vertebrata Palasiatica    2023, 61 (2): 123-141.   DOI: 10.19615/j.cnki.2096-9899.230112
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    The micromammal fossils collected from the upper part of the Jiaozigou Formation near Mansancun in 2015 are described. The sample consists of 10 species of six previously known genera (Amphechinus, Sinolagomys, Parasminthus, Litodonomys, Heterosminthus and Yindirtemys) belonging to three orders. Of them, four genera (Sinolagomys, Litodonomys, Heterosminthus and Yindirtemys) made their first appearance in the Late Oligocene and Sinolagomys kansuensis and Heterosminthus lanzhouensis are known only in the Late Oligocene. In comparison with the other Late Oligocene mammalian faunas known in China and Mongolia, the above assemblage appears to be contemporaneous with Xiagou, Taben-buluk, Yikebulage faunas and Tieersihabahe assemblages, but slightly younger than the Shargaltein-Tal Fauna in age. The Mansancun Fauna is also younger than the three Late Oligocene biozones recognized recently in Asia. Compared with the Yagou Fauna collected from the lower part of the Jiaozigou Formation, the Mansancun Local Fauna is clearly younger. Consequently, the Yagou Fauna would be early Late Oligocene, while the Mansancun Local Fauna may be considered late Late Oligocene. Thus, as a whole, the Jiaozigou Formation is Late Oligocene in age.

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    Restudy of Rhinocerotini fossils from the Miocene Jiulongkou Fauna of China
    LI Shi-Jie, DENG Tao
    Vertebrata Palasiatica    2023, 61 (3): 198-211.   DOI: 10.19615/j.cnki.2096-9899.230630
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    All the extant rhino species belong to Rhinocerotini and either have one horn (a nasal horn) or two horns (a nasal horn and frontal horn). So far, the earliest Rhinocerotini to have been identified in China is the “Dicerorhinuscixianensis, which was based on a juvenile skull with an associated mandible from the Middle Miocene locality of Jiulongkou in Cixian County, Hebei Province of northern China. Our analyses suggest that there are similarities between this specimen and the modern genus, Dicerorhinus, but it differs in several cranial traits and therefore cannot be assigned to the modern genus. Instead, it is closer to the Middle Miocene Lartetotherium from Europe, especially the specimen from La Retama in Spain and should be assigned to that genus, indicating the presence of intracontinental dispersal at this time. The Jiulongkou fauna is the only Middle Miocene fauna with Rhinocerotini in China, and, together with the faunal composition, this implies a more humid and closed environment, in contrast to those found in western China. We suggest that the position of the posterior border of the nasal notch is a good indication of the specimen’s evolutionary level in Rhinocerotini. The anterior position of the nasal notch as seen in modern Dicerorhinus, together with its certain similarities to L. cixianensis as well as its differences with more specialized species of the Dihoplus-Pliorhinus-Stephanorhinus -Coelodonta lineage, supports the conclusion that Dicerorhinus experienced little change during a nearly 10 Myr evolutionary history, possibly due to the low selection pressure seen in the tropical/subtropical forests in southeastern Asia.

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    Reappraisal of Bothriolepis sinensis Chi, 1940 from the Tiaomachien Formation, Hunan, China
    LUO Yan-Chao, ZHU Min, LU Li-Wu, PAN Zhao-Hui
    Vertebrata Palasiatica    2023, 61 (4): 261-276.   DOI: 10.19615/j.cnki.2096-9899.230901
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    Bothriolepis sinensis Chi 1940, mainly based on anterior median dorsal plates from the Middle Devonian Tiaomachien Formation of Hunan, is the first Paleozoic vertebrate taxon erected in China. Although additional materials of B. sinensis from the type locality were described by Lu in 1988, its morphology and phylogeny remain poorly understood. In this study, we complemented the morphology of the skull and trunk armor of B. sinensis based on Chi’s specimens housed in the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, and several previously undescribed specimens in the Geological Museum of China. Bothriolepis sinensis differs from other Bothriolepis in the following combination of characteristics: enlarged supraotic thickening, length/width ratio of head shield 1.4-1.6, broad orbital fenestra (greater than 1/3 of the head shield width), and fan-shaped preorbital recess. The phylogenetic analysis did not place B. askinae in the most basal position of the genus and revealed that B. sinensis and B. kwangtungensis consistently from a monophyletic group characterized by their slender proximal segment of the pectoral fin (length/width ratio greater than 7). A majority of Chinese Bothriolepis species (B. niushoushanensis , B. lochangensis , B. tungseni , B. kwangtungensis and B. sinensis ) were clustered in a clade characterized by the pectoral pit-line on the ventral central plate 1 extending to the ventral central plate 2. The paleogeographic reconstruction using the data from the DeepBone platform showed that Bothriolepis had its oldest occurrences in South China and East Gondwana in Eifelian, dispersed rapidly worldwide, and then diversified across the coasts of the Rheic Ocean.

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    A giant bamboo rat from the latest Miocene of Yunnan
    Lawrence J. FLYNN, LI Qiang, Jay KELLEY, Nina G. JABLONSKI, JI Xue-Ping, Denise F. SU, WANG Xiao-Ming
    Vertebrata Palasiatica    2023, 61 (4): 277-283.   DOI: 10.19615/j.cnki.2096-9899.230710
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    The Shuitangba subbasin lignite deposits of the Zhaotong Basin in northern Yunnan Province have produced vertebrate fossils of terminal Miocene age. We conducted test wet screening of fossiliferous sediment in 2014 to increase representation of small mammals. This effort produced four teeth of a very large bamboo rat, much larger than the previously known bamboo rat present at Shuitangba, and representing a new species. This new species is characterized by its molars being remarkably larger than those of other known species of Miorhizomys , and being hypsodont with cementum, and less anterorposteriorly compressed. The age of this new species from Shuitangba is in the range of 6.2 to 6.7 Ma. It appears that diverse bamboo rats of the extinct genus Miorhizomys were present in the Late Miocene of Yunnan, somewhat before the 6 Ma appearance of extant Rhizomys to the north in the vicinity of Shanxi Province.

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    Do chondrocytes within calcified cartilage have a higher preservation potential than osteocytes?A preliminary taphonomy experiment
    Alida M. BAILLEUL, WU Qian, LI Dong-Sheng, LI Zhi-Heng, ZHOU Zhong-He
    Vertebrata Palasiatica    2023, 61 (2): 108-122.   DOI: 10.19615/j.cnki.2096-9899.230309
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    Chondrocytes with remnants of nuclei and biomolecules were recently reported in two Cretaceous dinosaurs from North America and China. For multiple reasons, it was hypothesized that calcified cartilage (CC) had a better potential than bone to preserve ancient cells. Here we provide the first experimental test to this hypothesis by focusing on the most important variable responsible for cellular preservation: the postmortem blockage of autolysis. We compare the timing of autolysis between chondrocytes and osteocytes in an avian model (Anas platyrhynchos domesticus) buried for up to 60 days under natural conditions that did not inhibit autolytic enzymes. Within 15 days post-burial, almost all osteocytes were already cytolyzed but chondrocytes in CC were virtually unaffected. All osteocytes were cytolyzed after 30 days, but some chondrocytes were still present 60 days post-burial. Therefore, even in harsh conditions some CC chondrocytes still survive for months postmortem on a time scale compatible with permineralization. This is consistent with other data from the forensic literature showing the extreme resistance of hyaline cartilage (HC) chondrocytes after death and does support the hypothesis that CC has a better potential than bone for cellular preservation, especially in fossils that were not permineralized rapidly. However, because the samples used were previously frozen, it is possible that the pattern of autolysis observed here is also a product of cell death due to ice crystal formation and not strictly autolysis, meaning a follow-up experiment on fresh (non-frozen samples) is necessary to be extremely accurate in our conclusions. Nevertheless, this study does show that CC chondrocytes are very resistant to freezing, suggesting that chondrocytes are likely better preserved than osteocytes in permafrost fossils and mummies that underwent a freezing-thawing cycle. It also suggests that cartilage (both hyaline and calcified) may be a better substrate for ancient DNA than bone. Moreover, even though we warrant follow-up taphonomy experiments with non-frozen samples paired with DNA sequencing, we already urge ancient DNA experts to test CC as a new substrate for ancient DNA analyses in fossils preserved in hot and temperate environments as well.

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    The first description of Equidae (Perissodactyla, Mammalia) from Xinyaozi Ravine in Shanxi, North China
    DONG Wei, BAI Wei-Peng, LIU Wen-Hui, ZHANG Li-Min
    Vertebrata Palasiatica    2023, 61 (3): 212-244.   DOI: 10.19615/j.cnki.2096-9899.220926
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    Abundant mammalian fossils were uncovered during the field exploration for Nihewan beds at the beginning of the 1980s along Xinyaozi Ravine at Nangaoya Township of Tianzhen County, Shanxi Province in North China. But most equid material was not yet described except that of Equus stenonis. Six forms of Nihewanian equids were confirmed from the Xinyaozi specimens in the present study, five of which were described for the first time. They include four stenonids such as Equus sanmeniensis, E. teilhardi, E. huanghoensis and E. stenonis, and two hipparionines such as Hipparion (Proboscidipparion) sinense and H. (Plesiohiparrion) shanxiense. The diversification of stenonids in the Early Pleistocene was significant in North China with four taxa in Xinyaozi alone. The persistence of Neogene relics such as hipparionines was still present in the Early Pleistocene with two hipparionine taxa in Xinyaozi. Equus sanmeniensis and H. (Proboscidipparion) sinense were two representative equids not only coexisted in the Early Pleistocene but also widely distributed in China. The diversity of equids also implies the diversified vegetation on which they depended. The hypsodont dentitions and well developed cement, as well as completely molarized premolars of Xinyaozi equids indicate their abrasive diet mostly on monocotyledonous and grassland habitats with considerable scales enough to nourish six taxa of equids.

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    New findings of Xiyuichthys (Xiushuiaspidae, Galeaspida) from the Silurian of Jiangxi Province and Tarim Basin
    SHAN Xian-Ren, LIN Xiang-Hong, ZHANG Yu-Meng, LI Xu-Tong, GAI Zhi-Kun
    Vertebrata Palasiatica    2023, 61 (4): 245-260.   DOI: 10.19615/j.cnki.2096-9899.230904
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    New findings of the early Silurian Xiyuichthys (Xiushuiaspidae, Galeaspida), Xiyuichthys lixiensis sp. nov. and X. zhangi are described from the Qingshui Formation in Jiangxi Province and the Tataertag Formation in Tarim Basin respectively. X. lixiensis sp. nov. is characterized by the partially serrated lateral margin of the headshield and the ornamentation composed of extremely coarse granular tubercles (one tubercle per square millimetre). The complete early Silurian biostratigraphic sequence in northwestern Jiangxi warrants the erection of a standard section for the correlation of Silurian shallow marine red beds in South China and Tarim blocks. Thus, the finding of X. lixiensis from the Qingshui Formation (Silurian Lower Red Beds) in Jiujiang of Jiangxi bears important biostratigraphic significance. It can directly compare to X. zhangi from the Tataertag Formation in Tarim Basin on the specific level, which corroborates the correlations between the Tataertag Formation in Tarim Block and the Silurian Lower Red Beds in South China. Fossil records suggest that Xiushuiaspidae have a relatively broader stratigraphic range, but exhibit distinct composition at different stratigraphic horizons, with Xiyuichthys and Changxingaspis arising in the Silurian Lower Red Beds (Qingshui, Tangchiawu, and Tataertag formations) and Xiushuiaspis occurring in the Silurian Upper Red Beds (Xikeng Formation).

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    An egg clutch of the Stalicoolithidae discovered in Wuning, Jiangxi, China
    ZHOU Ming-Xiao, YAN Yun, QIU Wen-Jiang, FANG Kai-Yong, ZHU Xu-Feng, WANG Qiang, WANG Xiao-Lin
    Vertebrata Palasiatica    2023, 61 (4): 317-325.   DOI: 10.19615/j.cnki.2096-9899.230519
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    Here we describe an incomplete dinosaur clutch with three broken eggs and seven prints discovered in Wuning County, Jiangxi Province, that can be referred to Coralloidoolithus shizuiwanensis based on the following features: the eggs are nearly spheroid and arranged tightly and irregularly in the clutch, the eggshell thickness ranges 2.76-2.97 mm, the horizontal accretion lines are almost evenly distributed throughout the eggshell, and the secondary eggshell units are distributed in the medial and outer zones of the columnar layer. This egg clutch of Coralloidoolithus shizuiwanensis represents the first discovery of dinosaur eggs in Wuning County, and shows the age of the strata containing the dinosaur eggs in this area should be Late Cretaceous.

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    New material of Paukkaungmeryx minutus (Cetartiodactyla, Archaeomerycidae) from the late Middle Eocene Pondaung Formation, Myanmar
    Stéphane DUCROCQ, Yaowalak CHAIMANEE, Olivier CHAVASSEAU, Aung Naing SOE, Chit SEIN, Jean-Jacques JAEGER
    Vertebrata Palasiatica    2023, 61 (3): 182-197.   DOI: 10.19615/j.cnki.2096-9899.230522
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    We describe here new dental material from the locality of Myaukse Kyitchaung (Pondaung Formation, central Myanmar) that we refer to the primitive Archaeomerycidae ruminant Paukkaungmeryx minutus Ducrocq et al. (2020). The upper molars are morphologically very similar to those of the holotype and exhibit only slight variations on features like the better development of buccal and lingual cingula. The lower teeth display primitive characters including a simple p4 and bunoselenodont lower molars that lack folds on the back of the trigonid wall. This additional material makes Paukkaungmeryx the second archaeomerycid in Pondaung known by upper and lower teeth material, and documents the apparently complex early evolution of the family.

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    A skull of Early Pleistocene Paracamelus gigas (Artiodactyla, Mammalia) from Luotuo Hill in Dalian, Northeast China
    DONG Wei, LIU Wen-Hui, BAI Wei-Peng, LIU Si-Zhao, WANG Yuan, LIU Jin-Yuan, JIN Chang-Zhu
    Vertebrata Palasiatica    2024, 62 (1): 47-68.   DOI: 10.19615/j.cnki.2096-9899.230616
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    Originated in North America in the Middle Eocene, camelids were a successful group with very large diversity. But the camels emigrated to the Old World from North America, probably during the middle stage of the Middle Miocene, and did not radiate much as those in North America, represented by only two genera Paracamelus and Camelus. The former was considered as giving rise to the latter, but the detailed relationship of the Old World camelines was controversial. The new camel material unearthed from Layer 4 in the Jinyuan Cave at Luotuo Hill in Dalian, Liaodong peninsula in Northeast China, was described and referred to as Paracamelus gigas. Its dentition length is slightly longer than that of Camelus knoblochi but evidently larger than that of C. ferus and C. dromedarius. Based on the fossil records and morphometric evidences, P. gigas originated from a form similar to P. alexejevi in the Late Pliocene in the Old World, instead of from Megatylopus gigas of North America and then migrated into Asia as previously thought. The morphometric similarities between the Early Pleistocene Dalian specimens and those of the Middle and Late Pleistocene C. knoblochi indicate that P. gigas probably gave rise to C. knoblochi as formerly postulated and likely in the late Early Pleistocene by reduction or simplifying of P3 and P4, disappearance of p3 and shortening of dentition length. P. gigas inhabited in the forest steppe environment of Liaodong peninsula from 1.1 to 1.52 Ma based on paleomagnetic dating and pollen evidence.

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    Micromammal fossils from the basal part of the Jiaozigou Formation in Yagou area, Linxia Basin, Gansu Province
    WANG Ban-Yue, QIU Zhan-Xiang
    Vertebrata Palasiatica    2023, 61 (4): 284-316.   DOI: 10.19615/j.cnki.2096-9899.230927
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    Renewed fieldwork in 2003 produced a rich micromammal assemblage from the basal part of the Jiaozigou Formation in the Yagou area of Linxia Basin. 17 genera distributed among 13 families of three orders were recovered. The micromammal fauna is a typical Oligocene assemblage for Central and Eastern Asia. 14 genera (~82% of the fauna) are common in the Oligocene of Asia. Of them four genera and four species of Eucricetodon are restricted to the Oligocene, one genus (Bagacricetodon ) is restricted to Late Oligocene and Glis and Eomyodon made their first appearances in the Late Oligocene. Based on this micromammal composition, the basal part of the Jiaozigou Formation in the Yagou area could be mainly of Late Oligocene in age, which is in accordance with the conclusion based on large mammal fossils. In comparison with the other Late Oligocene micromammal faunas in Central and East Asia, the Yagou Fauna is slightly older than the Ulan III biozone of Nei Mongol and biozone C of Mongolia, because it has two Eocene genera and lacks more advanced genera. This is roughly in accordance with the recent palaeomagnetic interpretation for the Maogou section, where the lower boundary of the Jiaozigou Formation was correlated with Chron C10r (~29 Ma). The presence of large number of xerophilous zapodines, ctenodactylids, cricetids and lagomorphs combined with fossorial Tsaganomys and the lithology of the fossil-bearing deposits, composed of gypsiferous reddish brown mudstone, tend to show a semiarid woodland-shrubland habitat during the Late Oligocene in Yagou area. In Late Oligocene more frequent faunal interchange might have occurred between Asia and Europe (4 genera commonly shared) rather than between Asia and America (only 1 genus shared), partly because of the disappearance of the Turgai Strait.

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    Decline in phylogenetic diversity of Arthrodira (stem-group Gnathostomata) correlates with major Devonian bioevents
    XUE Qin-Yuan, YU Yi-Lun, PAN Zhao-Hui, ZHU You-An, ZHU Min
    Vertebrata Palasiatica    2024, 62 (1): 1-12.   DOI: 10.19615/j.cnki.2096-9899.231124
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    Arthrodira, the most diverse subgroup of placoderms, or jawed stem gnathostomes, is noted for their occupation of high trophic levels, especially in the later stage of their evolutionary history. Despite the relatively complete fossil record of arthrodires, the results of previous studies on the arthrodire diversity, based on counting the numbers of taxa in each time interval (raw or taxic diversity), correlate poorly with major Devonian bioevents. Here, we assemble a new, exhaustive dataset of arthrodires, comprising 450 species of 219 genera. Most taxa are integrated into a supertree integrating the results from various phylogenetic investigations. Our analysis of the phylogenetic diversity, accounting for the presence of ghost lineages, reveals a very different pattern compared to the raw diversity. The phylogenetic diversity of arthrodires exhibited a typical early burst pattern, peaking in the Early Devonian (Lochkovian-Pragian Boundary), and followed by declines that aligned well with several major bioevents. Near each of the first four events, the arthrodire diversity experienced only minor drops and generally persisted at high levels. The later three events, particularly the Frasnian-Famennian Boundary and Devonian-Carboniferous Boundary Events, led to steep declines in arthrodire diversity, from which they never recovered before their complete extinction in the end-Devonian. All these declines were not evident in the raw or taxic diversity pattern, except that related to the Frasnian-Famennian Boundary Event.

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    Reassessment of Trilophodon connexus Hopwood, 1935 and attributing it to the Choerolophodontidae
    LI Chun-Xiao, CHEN Jin, WANG Shi-Qi
    Vertebrata Palasiatica    2024, 62 (1): 33-46.   DOI: 10.19615/j.cnki.2096-9899.230917
    Abstract142)   HTML3)    PDF (1602KB)(168)       Save

    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 “Choerolophodonconnexus. “Choerolophodonconnexus 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 “Choerolophodonconnexus.

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    First report of Hispanodorcas from the Late Miocene of China
    WU Yong, WANG Shi-Qi, LIANG Zhi-Yong, GUO Ding-Ge, SUN Bo-Yang, LIU Long, DUAN Kai, CHEN Guo-Zhong
    Vertebrata Palasiatica    DOI: 10.19615/j.cnki.2096-9899.240123
    Accepted: 23 January 2024

    New suoid remains (Mammalia, Artiodactyla) from the Late Miocene of Haritalyangar, India
    Anek R. SANKHYAN, Olivier CHAVASSEAU
    Vertebrata Palasiatica    2024, 62 (1): 69-84.   DOI: 10.19615/j.cnki.2096-9899.231120
    Abstract69)   HTML5)    PDF (1762KB)(102)       Save

    We report here a number of mandibular, maxillary and dental fossil remains of Indian Suoidea from the Middle Siwalik of Haritalyangar area in Bilaspur District of Himachal Pradesh, North India. Haritalyangar is well known for the diversity of the Late Miocene fauna and the hominoids and other primates. The suoid remains were collected by one of the authors (ARS) during different field seasons and their localities were plotted on the map, along with those of the proboscidean reported recently, including the hominoid localities. The fossil localities are spread over the ‘Lower Alternations’ and the ‘Upper Alternations’ from Makkan Khad to Sir Khad. We have assigned the fossils into three genera, Propotamochoerus (P. hysudricus), Hippopotamodon (H. sivalense) and Yunnanochoerus (Y. dangari). Propotamochoerus hysudricus represents the most common suid in the Middle Siwaliks. The new remains of the suoid Yunnanochoerus dangari further documents this rare palaeochoerid only known in the Haritalyangar area by a few fossils. The new suoid remains show clear affinities with the Nagri fauna of the Pakistan Siwaliks. Biochronological correlations with the Potwar Plateau based on suoids indicate an age bracket of ~10-9 Ma for the ‘Lower Alternations’ of Haritalyangar, close to the bracket mostly recently proposed on the basis of magnetic polarity stratigraphy.

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