A new artiodactyl of moderate size is described on the basis of several dentaries and maxillae from the middle Eocene Subathu Group of the Kalakot area, Rajouri District, Jammu and Kashmir, India. Despite its general resemblance with the family Dichobunidae this taxon shares with Raoellidae two unambiguous characters: the presence of a hypoconulid on p4, and an asymmetrical P4. The position of the new taxon within the Cetacea / Raoellidae clade is strongly supported by eight non ambiguous synapomorphies, among which a cristid obliqua on lower molars anteriorly pointing towards the postectoprotocristid, and a P3 with only two roots. The new taxon is characterised by the following characters: a long symphysis; p3 and p4 with small parastylid and metastylid but no metaconid; lower molars with metaconid as the highest cusp, voluminous hypoconid, and absence of ‘hypolophid’; m1 and m2 with small paraconid, basally fused with metaconid, and small bifid tubercle-like hypoconulid; m3 with a crestiform paraconid; P3 and P4 with small protocone and shelf-like cingulae; upper molars with small paraconule and large metaconule (pseudohypocone); M1 and M2 with conical brachydont cusps; M3 with bunodont bulbous cusps; cristae and cingulae distinct and thick, presence of an ectoloph. The presence of a new primitive raoellid in the middle Eocene Subathu Group sheds new light on the phylogeny and paleobiogeography of basal raoellid artiodactyls. This work is partly funded by project BR/121/A3/PALEURAFRICA from the Belgian Science Policy Office.
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RBINS Staff Publications 2019
Multituberculates are an extinct rodent-like order that lived between Late Jurassic and late Eocene, on almost every continent. Due to their extraordinary longevity, their evolutive history is important to understand. One of the most numerous and best-preserved groups is the superfamily Djadochtatherioidea from the Late Cretaceous of the Gobi Desert. All djadochtatherioid genera are monospecific, except Kryptobaatar. The large number of K. dashzevegi fossils come from Outer Mongolia, while the only two specimens found in Bayan Mandahu, Inner Mongolia, China belong to K. mandahuensis. However, a new particularly well-preserved specimen (IMM 99BM-IV/5) found in Bayan Mandahu during the 1990s Sino-Belgian expeditions seems at first sight very close to K. dashzevegi. IMM 99BM-IV/5 consists of a skull associated with cervical and thoracic vertebrae, ribs, shoulder girdle, broken right humerus and an almost complete left forelimb. It is the first specimen for which the hand is described in detail. Based on micro-CT scan and comparison, it appears that IMM 99BM-IV/5 presents morphological characters of both species of Kryptobaatar, as well as new characters of its own. Phylogenetic analysis suggests that IMM 99BM-IV/5 has an intermediate position between K. dashzevegi and K. mandahuensis and could therefore belong to a new species. However, Kryptobaatar is paraphyletic in the resulting tree, which raises again questions about intraspecific variability in multituberculates. Since only 13 specimens of Kryptobaatar out of the hundreds found have been studied, it is impossible to reliably know if IMM 99BM-IV/5 is included in the variability of K. dashzevegi or not. However, it is crucial to know this variability to define whether the genus is monospecific or not. By comparing K. mandahuensis with published specimens, we concluded that it is a valid species. This work also highlighted the lack of knowledge of the variability of the type species K. dashzevegi, without which it is impossible to clearly assign IMM 99BM-IV/5. Finally, endemism alone is not the cause of this variability, but the role of paleoenvironment or age is currently unknown.
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RBINS Staff Publications 2021
