Chiyoumeryx shinaoensis Mennecart &amp; Aiglstorfer &amp; Li &amp; Li &amp; Wang 2021, nov. gen.
Creators: name: Mennecart, Bastien
name: Aiglstorfer, Manuela
name: Li, Yikun
name: Li, Chunxiao
name: Wang, ShiQi
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Artiodactyla
Lophiomerycidae
Chiyoumeryx
Chiyoumeryx shinaoensis

description: <i>Chiyoumeryx</i> nov. gen. <i>shinaoensis</i> (Miao, 198220). Figure 1B and Figure S2. *v1982 <i>Lophiomeryx shinaoensis</i> — Miao: 530, Table 3, Figs. 3– 520. v1987 <i>Lophiomeryx shinaoensis</i> — Janis: 203, 204, 211, 212, Fig. 8B 33. v <i>1997 Lophiomeryx shinaoensis</i> — Vislobokova: Fig. 321. v <i>2000 L. shinaoensis</i> — Guo, Dawson, and Beard: 247, Table 214. v <i>2001 L. shinaoensis</i> — Métais, Chaimanee, Jaeger, and Ducroq: 239–241, 24117. v <i>2012 L. shinaoensis</i> — Mennecart: 6234. <b>Neodiagnosis.</b> <i>Chiyoumeryx</i> nov. gen. <i>shinaoensis</i> is bigger than <i>Chiyoumeryx</i> nov. gen. <i>flavimperatoris</i> nov. sp. but smaller than? <i>Chiyoumeryx turagicus</i>. Te transversely oriented anterior conid in the p4 in <i>Chiyoumeryx</i> nov. gen. <i>shinaoensis</i> differs from the obliquely oriented one in <i>Chiyoumeryx</i> nov. gen. <i>flavimperatoris</i> nov.sp. In <i>Chiyoumeryx</i> nov. gen. <i>shinaoensis</i>, the posterolingual conid is vestigial on p4. <i>Chiyoumeryx</i> nov. gen. <i>shinaoensis</i> has no anterior cingulid, while in <i>Chiyoumeryx</i> nov. gen. <i>flavimperatoris</i> nov. sp. there is a tiny anterior cingulid. <i>Chiyoumeryx</i> nov. gen. <i>shinaoensis</i> possesses lower crowns than? <i>Chiyoumeryx</i> nov. gen. <i>turgaicus</i>. <i>Chiyoumeryx</i> nov. gen. <i>flavimperatoris</i> nov. sp. possesses an ectostylid, which is absent in? <i>Chiyoumeryx</i> nov. gen. <i>turgaicus</i>. Holotype. IVPP V 6531, right mandible with p2–m3 and tooth socket of p1. Paratype. IVPP V 6532, right fragmented maxillary with P4–M3. <b>Additional material.</b> IVPP V 6533, right mandible with p2–m3 and tooth socket of i1 –p1; IVPP V 6534, lef fragments mandible with m1–m3; IVPP V 6535, right fragmented mandible with m1–m3; IVPP V 6536, lef fragmented mandible with p4–m3; IVPP V 6537, right fragmented mandible with p4–m2; IVPP V 6538, lef p4; IVPP V 6539, right maxillary with P3–M3; IVPP V 6540, right maxillary with P4–M2; IVPP V 6541, right maxillary with M2–M3; IVPP V 6542, lef maxillary with P3–M1; IVPP V 6543, right maxillary with M1–M3; IVPP V 6544, Lef M3; IVPP V 6545, lef maxillary with P4–M3. Measurements are given in Table S1. Locality. Shinao Basin, Panxian County, Southwestern Guizhou, China. Late Eocene. <b>Taxonomical attribution.</b> Miao 20 attributed the here described specimens to the genus <i>Lophiomeryx</i> assuming that these fossils belong to a traguloid. “ <i>Lophiomeryx</i> ” <i>shinaoensis</i> clearly is a Lophiomerycidae: anterior and posterior fossae are open on the lower molars due to the absence of a premetacristid and the extreme reduction or absence of a postentocristid, there is no external postprotocristid, there is a mesolingual conid on the p4, the symphysis of the mandible extends backward up to the p 12, 36. It also shares with undisputable Lophiomerycidae a reduced posthypoconulidcristid that does not enclose the third lobe lingually. <i>“ Lophiomeryx ” shinaoensis</i> differs from <i>Zhailimeryx</i> and <i>Krabimeryx</i> in the absence of the entoconidian groove 14, 17. Moreover, the teeth are more laterally compressed in <i>“ Lophiomeryx ” shinaoensis</i> and the metaconid is linguo-labially more centeral 14, 17. Te posthypoconulidcristid in <i>“ Lophiomeryx ” shinaoensis</i> is more elongated than in <i>Krabimeryx</i> and its p4 has an extended posterior part, while it is reduced in <i>Krabimeryx</i> 17. Contrary to what was suggested by Métais and Vislobokova 2, <i>Miomeryx altaicus</i> 24 is currently known only by its holotype, which is an upper tooth row (AMNH 20383, see Matthew and Granger 24). Comparable to <i>M. altaicus</i>, the postprotocrista reaches the premetaconulecrista on the M2 in <i>“ Lophiomeryx ” shinaoensis</i>. Tese two cristae fuse totally on the M3 in the here described specimens. However, even if both genera also bear a very strong cingulum, <i>“ Lophiomeryx ” shinaoensis</i> clearly differs from <i>M. altaicus</i> in having broader and squarer molars and straighter lingual cristae in the P4. Miao 20 compared the here revised fossils with the seven <i>Lophiomeryx</i> species considered valid at that time. Unfortunately, very few specimens document most of these species and there is considerable doubt considering the genus attribution of most of them 34, 36 – 39. In any case, we agree with Miao 20 (p. 535) that “ <i>L.</i> [= <i>Praetragulus</i>] <i>gobiae</i> is readily distinguished from other known <i>Lophiomeryx</i> species as well as from <i>L. shinaoensis</i> by the absence of p1, the anterior flange of metaconid joining protoconid crescent.”. Miao 20 (p. 535) already noticed that “ <i>Lophiomeryx chalaniati</i>, <i>Lophiomeryx gaudry</i> [= <i>Iberomeryx minor</i>], and <i>Lophiomeryx benarensis</i> are radically different from the present specimens in the anterior branches of the protoconid crescent [= preprotocristid], of m1 and m2 not reaching the lingual border while the posterior branches of hypoconid crescent [= posthypocristid], doing so”. <i>“ Lophiomeryx ” shinaoensis</i> shares this condition with the Mongolian <i>Lophiomeryx angarae</i> 24. However, the trigonid is smaller than the talonid on m1 and m2 in <i>“ Lophiomeryx ” shinaoensis</i> and the preprotocristid ends in the labio-lingual axis of the molars, while trigonid and talonid are of more similar width 5 combined with a longer preprotocristid in the European <i>Lophiomeryx</i> species and <i>L. angarae</i> 16, 34, 37. Te shape of the P4 in <i>“ Lophiomeryx ” shinaoensis</i> is very different from <i>Lophiomeryx</i> (see Brunet and Sudre 37, Figs. 4 and 6). In <i>Lophiomeryx</i>, the posterolingual crista fuses with the posterolabial crista. In <i>“ Lophiomeryx ” shinaoensis</i>, the curved posterolingual crista does not join the distal end of the posterolabial crista but reaches the labial side. Furthermore, <i>“ Lophiomeryx ” shinaoensis</i> clearly differs from <i>L. angarae L. mouchelini</i>, and <i>L. chalaniati</i> in the shape of the mandible. Tese three species of <i>Lophiomeryx</i> possess a very elongated diastema between c and p1 and a small one between p1 and p 224, 36, 37. As part of the genus diagnosis, Mennecart 34 (p. 62 and p. 67), adapted from Brunet and Sudre 37 and Métais and Vislobokova 2, noticed that “the <i>corpus mandibulae</i> presents [in <i>Lophiomeryx</i>: <i>L. angarae</i>, <i>L. mouchelini</i>, and <i>L. chalaniati</i> 24, 34, 37] a concave ventral profile just behind the mandible symphysis, then it becomes regularly convex until the beginning of the ramus, where there is a rounded <i>incisura vasorum</i>. […] On the anterior part of the mandible there are two <i>foramen mentale</i>.” Moreover he wrote that the “p1 is always reduced and leaf-like, separated from c and p2 by diastemata.” (Mennecart 34, p. 67). In <i>“ Lophiomeryx ” shinaoensis</i> there is no diastema between p1 and p2 and the diastema between c and p1 is extremely reduced. Te p1 is relatively big considering the root size. Te lower outline of the mandible in lateral view is relatively straight. <i>“ Lophiomeryx ” shinaoensis</i> shares these characteristics with “ <i>Lophiomeryx</i> ” <i>turgaicus</i> 40.Miao 20 (p. 535) already noticed strong similarities between “ <i>Lophiomeryx</i> ” <i>turgaicus</i> and <i>“ Lophiomeryx ” shinaoensis</i>. Te lower premolars of “ <i>Lophiomeryx</i> ” <i>turgaicus</i> and <i>“ Lophiomeryx ” shinaoensis</i> are strongly laterally compressed and the p4 is rectangular, giving the lower premolar toothrow an more elongated aspect than in <i>L. angarae</i>, <i>L. mouchelini</i>, and <i>L. chalaniati</i> 20, 24, 30, 38, 40. Moreover, in these two species, the posthypoconulidcristid is of similar length, longer than in <i>L. angarae</i>, <i>L. mouchelini</i>, and <i>L. chalaniati</i>. Based on these observations, we can assume that <i>“ Lophiomeryx ” shinaoensis</i> and “ <i>Lophiomeryx</i> ” <i>turagicus</i> cannot be assigned to the genus <i>Lophiomeryx</i> and may both belong to the same new Lophiomerycidae genus that we here name <i>Chiyoumeryx</i> nov. gen. <i>Chiyoumeryx</i> nov. gen. <i>shinaoensis</i> differs from? <i>Chiyoumeryx</i> nov. gen. <i>turgaicus</i> nov. comb. in being lower crowned, smaller, possessing an ectostylid, having the symphysis starting under p1, and a shorter diastema.
description: Published as part of <i>Mennecart, Bastien, Aiglstorfer, Manuela, Li, Yikun, Li, Chunxiao &amp; Wang, ShiQi, 2021, Ruminants reveal Eocene Asiatic palaeobiogeographical provinces as the origin of diachronous mammalian Oligocene dispersals into Europe, pp. 1-12 in Scientific Reports 1</i> on pages 5-6, DOI: 10.1038/s41598-021-96221-x, http://zenodo.org/record/5645747
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