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Reassessment of Trilophodon connexus Hopwood, 1935 and attributing it to the Choerolophodontidae

  • LI Chun-Xiao ,
  • CHEN Jin ,
  • WANG Shi-Qi
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  • 1 University of Chinese Academy of Sciences Beijing 100049
    2 Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences Beijing 100044

Received date: 2022-05-26

  Online published: 2023-09-18

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 “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.

Cite this article

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

References

[1] Barbour E H, Sternberg G F, 1935. Gnathabelodon thorpei, gen. et sp. nov., a new mud-grubbing mastodon. Bull Nebr State Mus, 42: 395-403
[2] Chen G F, 1988. Mastodont remains from the Miocene of Junggar Basin in Xinjiang. Vert PalAsiat, 26: 265-277
[3] Chen G F, 2021. Basal synapsids and mammals:hyracoidea, proboscidea, etc. In: Qiu Z X, Li C K eds. Palaeovertebrata Sinica. Beijing: Science Press. 1-231
[4] Chow M C, Chang Y P, 1974. Chinese Fossil Elephantoids. Beijing: Science Press. 1-74
[5] Gaziry A W, 1987. New mammals from the Jabal Zaltan site, Libya. Senckenbergiana Lethaea, 68: 69-89
[6] Hopwood A T, 1935. Fossil Proboscidea from China. Palaeontol Sin, Sér C, 9: 1-108
[7] Konidaris G E, Koufos G D, Kostopoulos D S et al., 2016. Taxonomy, biostratigraphy and palaeoecology of Choerolophodon (Proboscidea, Mammalia) in the Miocene of SE Europe-SW Asia: implications for phylogeny and biogeography. J Syst Palaeont, 14: 1-27
[8] Li, C X, Wang S Q, Hao C L et al., 2018. A textual research of the early localities of fossil Gomphotherium in the Xining Basin with relevant stratigraphic correlation. J Stratigr, 42: 313-324
[9] Li C X, Wang S Q, Mothé D et al., 2019. New fossils of Early and Middle Miocene Choerolophodon from northern China reveal a Holarctic distribution of Choerolophodontidae. J Vert Paleont, 39: e1618864
[10] Li C X, Wang S Q, Yang Q, 2022. Discovery of a primitive Gomphotherium from the Early Miocene of northern China and its biochronology and palaeobiogeography significance. Hist Biol, doi: 10.1080/08912963.2022.2077106
[11] MacInnes D G, 1942. Miocene and post-Miocene Proboscidea from east Africa. Trans Zool Soc London, 25: 33-106
[12] Maglio V J, 1974. A new proboscidean from the Late Miocene of Kenya. Palaeontology, 17: 699-705
[13] Matthews S C, 1973. Notes on open nomenclature and on synonymy lists. Palaeontology, 16: 713-719
[14] Osborn H F, 1936. Proboscidea: a Monograph of the Discovery, Evolution, Migration and Extinction of the Mastodonts and Elephants of the World. New York: The American Museum Press. 1-802
[15] Pickford M, 2001. Afrochoerodon nov. gen. kisumuensis (MacInnes) (Proboscidea, Mammalia) from Cheparawa, Middle Miocene, Kenya. Ann Paléont, 87: 99-117
[16] Qiu Z D, Li C K, Wang S J, 1981. Miocene mammalian fossils from Xining Basin, Qinghai. Vert PalAsiat, 19: 156-173
[17] Sanders W J, Miller E R, 2002. New proboscideans from the Early Miocene of Wadi Moghara, Egypt. J Vert Paleont, 22: 388-404
[18] Sanders W J, Gheerbrant E, Harris J M et al., 2010. Proboscidea. In: Werdelin L, Sanders W J eds.eds. Cenozoic Mammals of Africa. Berkeley: University of California Press. 161-251
[19] Sellards E H, 1940. New Pliocene mastodon. Bull Geol Soc Am, 51: 1659-1664
[20] Shoshani J, Tassy P, 2005. Advances in proboscidean taxonomy & classification, anatomy & physiology, and ecology & behavior. Quat Int, 126-128: 5-20
[21] Tassy P, 1983. Les Elephantoidea Miocènes du Plateau du Potwar, Groups de Siwalik, Pakistan. Ann Paléont, 69: 99-136, 235-297
[22] Tassy P, 1985. La place des mastodontes Miocènes de l’ancien monde dans la phylogénie des Proboscidea (Mammalia): hypothèses et conjectures. Vol I-III. Thèse Doctorat ès Sciences. Paris: Université Pierre et Marie Curie. 1-861
[23] Tassy P, 2014. L'odontologie de Gomphotherium angustidens (Cuvier, 1817) (Proboscidea, Mammalia): données issues du gisement d'En Péjouan (Miocène moyen du Gers, France). Geodiversitas, 36(1): 35-115
[24] Tobien H, 1973. On the evolution of mastodonts (Proboscidea, Mammalia), part 1: the bunodont trilophodont groups. Notizbl Hess L-Amt Bodenforsch, 101: 202-276
[25] Tobien H, 1980. A note on the skull and mandible of a new choerolophodont mastodont (Proboscidea, Mammalia) from the Middle Miocene of Chios (Aegean Sea, Greece). In: Jacobs L ed. Aspects of Vertebrate History: Essays in Honor of Edwin Harris Colbert. Flagstaff: Museum of Northern Arizona Press. 299-307
[26] Tobien H, Chen G F, Li Y Q, 1986. Mastodonts (Proboscidea, Mammalia) from the Late Neogene and Early Pleistocene of the People’s Republic of China, part I: historical account: the genera Gomphotherium, Choerolophodon, Synconolophus, Amebelodon, Platybelodon, Sinomastodon. Mainzer Geowiss Mitt, 15: 119-181
[27] Wang S Q, 2014. Gomphotherium inopinatum, a basal Gomphotherium species from the Linxia Basin, China, and other Chinese members of the genus. Vert PalAsiat, 52: 183-200
[28] Wang S Q, 2021. The anthracotheres from northern Junggar Basin and their palaeoclimatic significance in relation to the Tibetan Plateau. Palaeobio Palaeoenv, 101: 839-852
[29] Wang S Q, Deng T, 2011. The first Choerolophodon (Proboscidea, Gomphotheriidae) skull from China. Sci China Earth Sci, 54: 1326-1337
[30] Wang S Q, Duangkrayom J, Yang X W, 2015. Occurrence of the Gomphotherium angustidens group in China, based on a revision of Gomphotherium connexum (Hopwood, 1935) and Gomphotherium shensiensis Chang and Zhai, 1978: continental correlation of Gomphotherium species across the Palearctic. Pal?ont Z, 89: 1073-1086
[31] Wang S Q, Li Y, Duangkrayom J et al., 2017. A new species of Gomphotherium (Proboscidea, Mammalia) from China and the evolution of Gomphotherium in Eurasia. J Vert Paleont, 37: 1-15
[32] Wang S Q, Zhang X X, Li C X, 2020. Reappraisal of Serridentinus gobiensis Osborn & Granger and Miomastodon tongxinensis Chen: the validity of Miomastodon. Vert PalAsiat, 58: 134-158
[33] Wang S Q, Ye J, Meng J et al., 2022. Sexual selection promotes giraffoid head-neck evolution and ecological adaptation. Science, 376: 6597
[34] Wang S Q, Li C X, Li Y et al., 2023. Gomphotheres from Linxia Basin, China, and their significance in biostratigraphy, biochronology, and paleozoogeography. Palaeogeogr Palaeoclimat Palaeoecol, 613: 111405
[35] Wu Y, Deng T, Hu Y W et al., 2018. A grazing Gomphotherium in Middle Miocene Central Asia, 10 million years prior to the origin of the Elephantidae. Sci Rep, 8: 7640
[36] Zhai R J, 1961. On a collection of Neogene mammals from Ching-An, eastern Kansu. Vert PalAsiat, (3): 262-268
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