DOI: 10.15468/3eddvz
title: Neochorlakkia myaingensis n. gen., n. sp., a new Dichobunidae (Mammalia, Cetartiodactyla) from the middle Eocene Pondaung Formation, Myanmar

description: This dataset contains the digitized treatments in Plazi based on the original journal article Ducrocq, Stéphane, Soe, Aung Naing, Sein, Chit, Chaimanee, Yaowalak, Chavasseau, Olivier, Jaeger, Jean-Jacques (2022): Neochorlakkia myaingensis n. gen., n. sp., a new Dichobunidae (Mammalia, Cetartiodactyla) from the middle Eocene Pondaung Formation, Myanmar. Comptes Rendus Palevol 21 (4): 115-122, DOI: 10.5852/cr-palevol2022v21a4, URL: http://dx.doi.org/10.5852/cr-palevol2022v21a4ABSTRACTThe diversity of basal ungulates is significant in the late middle Eocene Pondaung Formation (Myanmar). However, the precise identification or attribution of some fossils is sometimes difficult because of the scarcity and poor preservation of the material. We describe here a new genus and species of a Dichobunidae from Paukkaung Kyitchaung 2 locality, that is morphologically and probably phylogenetically close to a taxon from the early-middle Eocene of Pakistan, and we discuss the attribution of dental material to Myanmarius chitseini Tsubamoto, Egi, Takai, Htike & Zin-Maung-Maung-Thein, 2013, an inderterminate artiodactyl from Pondaung. This study also confirms that dispersals were possible between the Indian subcontinent and Southeast Asia during the first part of the Eocene.RÉSUMÉNeochorlakkia myaingensis n. gen., n. sp., un nouveau Dichobunidae (Mammalia, Cetartiodactyla) de l’Eocène moyen de la formation de Pondaung, Myanmar.La diversité des ongulés basaux est importante dans la formation de Pondaung (fin de l’Eocène moyen) au Myanmar. Cependant, l’identification ou même l’attribution précises de certains fossiles sont parfois difficiles du fait de la pauvreté et de la mauvaise préservation du matériel. Nous décrivons ici un nouveau genre et une nouvelle espèce de Dichobunidae de la localité de Paukkaung Kyitchaung 2, proche morphologiquement et probablement phylogénétiquement d’un taxon de l’Eocène inférieur-moyen du Pakistan, et nous proposons une discussion sur l’attribution du matériel dentaire de Myanmarius chitseini Tsubamoto, Egi, Takai, Htike & Zin-Maung-Maung-Thein, 2013, un artiodactyle indéterminé de Pondaung. Ce travail confirme également la possibilité d’échanges fauniques pendant la première partie de l’Eocène, entre le sous-continent Indien et l’Asie du Sud-Est. MOTS CLÉS Myanmar,formation de Pondaung, fin de l’Eocène moyen, Cetratiodactyla, Dichobunidae, genre nouveau, espèce nouvelle. INTRODUCTION The late middle Eocene Pondaung fauna is characterized by its rich diversity of perissodactyls, anthracothere artiodactyls, and primates. However, recent studies have revealed that a significant number of basal “ungulates” also diversified in this area and represents a large proportion of the mammalian community (Ducrocq et al. 2000; Métais 2006; Métais et al. 2007; Tsubamoto et al. 2012; Ducrocq et al. 2016; Ducrocq 2019), most of them being represented by fragmentary remains and thus of uncertain affinities. Particularly, Tsubamoto et al. (2005: fig. 2B, C) described two upper molars from Pondaung that they referred to an indeterminate artiodactyl. Theodor et al. (2007) later suggested that this material might be related to the Raoellidae, a family of Asian small Eocene artiodactyls closely related to the Cetacea. In their revision of the dental features of the family Raoellidae, Orliac & Ducrocq (2012) demonstrated that the molars described by Tsubamoto et al. (2005) was not part of the raoellid clade, but was probably more closely related to the Suoidea. Tsubamoto et al. (2013) then re-examined this material, creating the genus and species Myanmarius chitseini Tsubamoto, Egi, Takai, Htike & Zin-Maung-Maung-Thein, 2013, and attributed two additional upper molars and a fragmentary and worn distal part of a lower molar to this taxon. According to them, Myanmarius Tsubamoto, Egi, Takai, Htike & Zin-Maung-Maung-Thein, 2013 was closely related to either the raoellids or the suoids depending on the inclusion of the fragmentary lower molar or not in their phylogenetic study. There is no strong evidence that the upper and lower molars described byTsubamoto et al. (2005, 2013) belong to the same taxon because they were not found in association. Indeed, Tsubamoto et al. (2013) only considered matching size, bunodonty and the occurrence of a distobuccal wear facet on the worn m3 to associate this tooth with the upper molars and to attribute it to Myanmarius. We describe here a complete isolated m3 recently found in the locality of Paukkaung Kyitchaung 2 (Fig. 1) that is almost identical to the fragmentary m3 illustrated by Tsubamoto et al. (2013), and we attribute both of them to a new genus and species distinct from Myanmarius chitseini. This complete lower molar displays additional morphological information that will allow discussing its systematic relationships, and that also might help understanding the status of the material referred to Myanmarius. ABBREVIATIONS Site and institutional abbreviations GSP-UM Geological Survey of Pakistan, University of Michigan, Ann Arbor; IVPP Institute of Vertebrate Paleontology and Paleoanthropology, Beijing; MFP-PK2 Myanmar French Paleontology, Paukkaung kyitchaung 2 Collections at the Myanmar Ministry of Culture, Nay Pyi Taw; NMMP-KU National Museum, Myanmar, Paleontology, Kyoto University, Kyoto; ZIN Zoological Institute, Russian Academy of Sciences, Saint Petersburg.The late middle Eocene Pondaung fauna is characterized by its rich diversity of perissodactyls, anthracothere artiodactyls, and primates. However, recent studies have revealed that a significant number of basal “ungulates” also diversified in this area and represents a large proportion of the mammalian community (Ducrocq et al. 2000; Métais 2006; Métais et al. 2007; Tsubamoto et al. 2012; Ducrocq et al. 2016; Ducrocq 2019), most of them being represented by fragmentary remains and thus of uncertain affinities. Particularly, Tsubamoto et al. (2005: fig. 2B, C) described two upper molars from Pondaung that they referred to an indeterminate artiodactyl. Theodor et al. (2007) later suggested that this material might be related to the Raoellidae, a family of Asian small Eocene artiodactyls closely related to the Cetacea. In their revision of the dental features of the family Raoellidae, Orliac & Ducrocq (2012) demonstrated that the molars described by Tsubamoto et al. (2005) was not part of the raoellid clade, but was probably more closely related to the Suoidea. Tsubamoto et al. (2013) then re-examined this material, creating the genus and species Myanmarius chitseini Tsubamoto, Egi, Takai, Htike & Zin-Maung-Maung-Thein, 2013, and attributed two additional upper molars and a fragmentary and worn distal part of a lower molar to this taxon. According to them, Myanmarius Tsubamoto, Egi, Takai, Htike & Zin-Maung-Maung-Thein, 2013 was closely related to either the raoellids or the suoids depending on the inclusion of the fragmentary lower molar or not in their phylogenetic study.There is no strong evidence that the upper and lower molars described byTsubamoto et al. (2005, 2013) belong to the same taxon because they were not found in association. Indeed, Tsubamoto et al. (2013) only considered matching size, bunodonty and the occurrence of a distobuccal wear facet on the worn m3 to associate this tooth with the upper molars and to attribute it to Myanmarius. We describe here a complete isolated m3 recently found in the locality of Paukkaung Kyitchaung 2 (Fig. 1) that is almost identical to the fragmentary m3 illustrated by Tsubamoto et al. (2013), and we attribute both of them to a new genus and species distinct from Myanmarius chitseini. This complete lower molar displays additional morphological information that will allow discussing its systematic relationships, and that also might help understanding the status of the material referred to Myanmarius.ABBREVIATIONSSite and institutional abbreviationsGSP-UM Geological Survey of Pakistan, University of Michigan, Ann Arbor;IVPP Institute of Vertebrate Paleontology and Paleoanthropology, Beijing;MFP-PK2 Myanmar French Paleontology, Paukkaung kyitchaung 2 Collections at the Myanmar Ministry of Culture, Nay Pyi Taw;NMMP-KU National Museum, Myanmar, Paleontology, Kyoto University, Kyoto;ZIN Zoological Institute, Russian Academy of Sciences, Saint Petersburg.