Chiyoumeryx, Mennecart & Aiglstorfer & Li & Li & Wang, 2021

Mennecart, Bastien, Aiglstorfer, Manuela, Li, Yikun, Li, Chunxiao & Wang, ShiQi, 2021, Ruminants reveal Eocene Asiatic palaeobiogeographical provinces as the origin of diachronous mammalian Oligocene dispersals into Europe, Scientific Reports 1, pp. 1-12 : 6-7

Chiyoumeryx nov. gen. flavimperatoris nov. sp.

Figure 1C and Figure S3.

v1961 cf. Miomeryx sp. — Xu: 316, 323, 32426.

v pars1982 Lophiomeryx gracilis — Miao: 532, Table 3, Fig. 9a,b 20.

v non1982 Lophiomeryx gracilis ?— Miao: 536, Fig. 820.

1983 Lophiomeryx sp. — Wang & Zhang: 122, 12741.

v 1983 cf. Miomeryx sp. — Wang & Zhang: 12341.

v 1997 Miomeryx sp. — Vislobokova: Fig. 321.

v pars 1997 L. gracilis — Vislobokova: Fig. 321.

v 1999 cf. Miomeryx sp. — Zhang, Long, Ji, & Ding: 7, Table 527.

v pars 2000 L. gracilis — Guo, Dawson, and Beard: 247, Table 214.

v pars 2001 L. gracilis — Métais, Chaimanee, Jaeger, and Ducrocq: 239, 24117.

v 2007 Miomeryx sp. — Métais and Vislobokova: 1942.

v pars 2012 L. gracilis — Mennecart: 6234.

ZooBank LSID. urn:lsid:zoobank.org:act:1DF6F58C-F08B-4657-BD4A-7C597653926F.

Etymology. meaning yellow (flavor-) emperor (imperatoris) in latin. Chiyou fought with the Yellow Emperor, the ancestor of Chinese, but was defeated.

Diagnosis. Chiyoumeryx nov. gen. flavimperatoris nov. sp. shows the above-mentioned characteristics of the genus. Chiyoumeryx nov. gen. flavimperatoris nov. sp. is smaller than Chiyoumeryx nov. gen. shinaoensis and? Chiyoumeryx nov. gen. turgaicus. Te p4 of Chiyoumeryx nov. gen. flavimperatoris nov. sp. differs from Chiyoumeryx nov. gen. shinaoensis by an oblique anterior conid, which is labio-lingually oriented in the larger species. A very short posterolingual conid is located between the posterolabial cristid and the transverse cristid in the p4 of Chiyoumeryx nov. gen. flavimperatoris nov. sp., while it is absent on Chiyoumeryx nov. gen. shinaoensis. In Chiyoumeryx nov. gen. flavimperatoris nov. sp., there is a tiny anterior cingulid, while it is absent in Chiyoumeryx nov. gen. shinaoensis.

Holotype. IVPP V 6547 , right mandible with p4–m3 (previously attributed to Lophiomeryx gracilis 20) .

Paratype. IVPP V 6548 , lef mandible with p4–m3 (previously attributed to Lophiomeryx gracilis 20).

Additional material. IVPP V 2600 , lef p4–m2 (previously attributed to cf. Miomeryx sp. 26). Measurements are given in Table S1.

Localities. Yangjiachong locality lying in the Caijiachong marls, Qujing , Yunnan, China; Shinao Basin , Panxian County, Southwestern Guizhou, China. Late Eocene .

Scientific Reports |

Taxonomical attribution. IVPP V 6547 and IVPP V 6548 from Shinao were previously attributed to Lophiomeryx gracilis 20, while IVPP V 2600 from Caijiachong marls was first described as cf. Miomeryx sp. 26. All these specimens share the same size and dental morphology, and originate from a similar stratigraphic position. Tat is why we attribute them to the same species.

None of these specimens can be attributed to Krabimeryx or Zhailymeryx, as the entoconidian groove is absent 14, 17. Furthermore, the external postmetacristid is more marked in the considered specimens than in Krabimeryx and Zhailymeryx, forming a deep groove. Te third basin is also very different in the here-described specimens from Krabimeryx and Zhailymeryx: the third lobe is a little tilted parallel with the prehypoconulidcristid and posthypoconulidcristid. Te back fossa of m3 is very narrow.

Furthermore, the here-described specimens can be distinguished from K. gracilis (previously attributed to the same species), by a smaller size and a slenderer shape. Te ectostylid is smaller than in K. gracilis . Te anterior cingulid in the lower molars is stronger in K. gracilis than in the here-considered specimens. Te small postentocristid (especially on m3) of the here-described specimens is absent in K. gracilis .

Te here-described specimens possess all characteristics in the lower molars that are typical for Chiyoumeryx nov. gen. and distinguish this genus from Lophiomeryx 24, 34, 37. Furthermore, as in Chiyoumeryx nov. gen. shinaoensis, the p4 is laterally compressed giving it a more elongated aspect than in Lophiomeryx 24, 34, 37. Terefore, we consider it justified assigning the here-described specimens to Chiyoumeryx nov. gen. However, they differ from Chiyoumeryx nov. gen. shinaoensis in as smaller size and the morphology of the p4: (1) the anterior conid is oblique while it is labio-lingually oriented in Chiyoumeryx nov. gen. shinaoensis. (2) Tere is a tiny anterior cingulid that is absent in Chiyoumeryx nov. gen. shinaoensis. (3) Tere is no additional cristid on the mesolingual conid, which is a well-rounded conid, while in Chiyoumeryx nov. gen. shinaoensis, there is a short posterolingual cristid. (4) Te posterolingual conid stands between the posterolabial cristid and the transverse cristid, while in Chiyoumeryx nov. gen. shinaoensis, the posterolingual conid is very small and oblique between the transverse cristid and the posterior stylid and does not join the posterolabial cristid. Due to these distinct differences we erect a new species: Chiyoumeryx nov. gen. flavimperatoris nov.sp.

Figures

Figure 1. Dentition of Krabimeryx gracilis nov. comb. (Miao, 1982)20 (A, B, G, H), Chiyoumeryx nov. gen. shinaoensis (Miao, 1982)20 (C, D), Chiyoumeryx nov. gen. flavimperatoris nov. sp. (E) and Iberomeryx miaoi nov. sp. (F–I). Krabimeryx gracilis nov. comb.(Miao, 1982)20: (A) IVPP V 6546-1 (holotype), partial skull with right and lef M1–M3; (B) IVPP V 6546-2 (holotype), right fragmented mandible with m2–m3. Chiyoumeryx nov.gen. shinaoensis (Miao, 1982)20: (C) IVPP V 6531 (holotype), right mandible with p2–m3 and tooth socket of p1; (D) IVPP V 6532 (paratype), right fragmented maxillary with P4-M3. Chiyoumeryx nov. gen. flavimperatoris nov. sp.: (E) IVPP V 6547 (holotype), right mandible with p4–m3; Iberomeryx miaoi nov. sp.: (F) IVPP V 6551 (holotype), lef mandible with m1–m3 (mirrored); (G) lower molar Lophiomerycidae dental nomenclature (based on the m3 of IVPP 6546-2): 1 internal postmetacristid, 2 metaconid, 3 external postmetacristid, 4 internal preentocristid, 5 entoconidian groove, 6 external preentocristid, 7 entoconid, 8 posthypoconulidcristid, 9 hypoconulid, 10 prehypoconuldicristid, 11 posthypocristid, 12 hypoconid, 13 prehypocristid, 14 ectostylid, 15 postprotocristid, 16 protoconid, 17 preprotocristid, 18 anterior cingulid; (H) upper molar Lophiomerycidae dental nomenclature (based on the M2 of IVPP 6546-1): 1 postmetacrista, 2 metacone, 3 premetacrista, 4 mesostyle, 5 postparacrista, 6 paracone, 7 paraconid labial groove, 8 preparacrista, 9 parastyle, 10 preprotocrista, 11 anterolingual cingulum, 12 protocone, 13 postprotocrista, 14 entostyle, 15 additional cone, 16 premetaconulecrista, 17 metaconule, 18 postmetaconulecrista; (I) lower molar Tragulidae dental nomenclature (based on the m2 of IVPP V 6551, reversed): 1 metaconid, 2 external postmetacristid, 3 Dorcatherium fold, 4 internal postmetacristid, 5 preentocristid, 6 entoconid, 7 postentocristid, 8 posterior cingulid, 9 posthypocristid, 10 hypoconid, 11 prehypocristid, 12 ectostylid, 13 external postprotocristid, 14 Tragulus fold, 15 internal postprotocristid, 16 protoconid, 17 preprotocristid, 18 paraconid, 19 preparacristid. (J) phylogenetic position and stratigraphie of the Shinao/ Yangjiachong/Xiaerhete ruminants (topology2). a stem Ruminantia, b Archaeomeryx, c Chiyoumeryx nov.gen. and Krabimeryx gracilis, d crown Ruminantia, e Iberomeryx miaoi nov. sp.; 1 lingual view, 2 occlusal view. Scale bare is 1 cm.