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The phylogeny and classification of the Dinocerata (Mammalia, Eutheria)
... The orders Roden鄄 tia and Dinocerata and an important number of families make their first appearance in the Ga鄄 shatan. For Rodentia ( Meng et al., 1994 Meng et al., , 2003 Asher et al., 2005) and Dinocerata ( Schoch and Lucas, 1985; Beard, 1998) it has been argued that these groups evolved in Asia during the Paleocene, and also limnocyonine hyaenodontids appear earlier in Asia than anywhere else in Laurasia ( Bowen et al., 2002) . On the other hand, for taeniolabidid and neoplagiaulacid multituberculates, nyctitheriids, cimolestids, and carpolestids, more primitive forms are known from older faunas in North America but not in Asia, and these taxa are most probably North American immigrants. ...
... Biogeography摇 The presence of the families Neoplagiaulacidae, Taeniolabididae, Nyc鄄 titheriidae, Cimolestidae and Carpolestidae in Gashatan faunas indicates the appearance of North American immigrants in Asian faunas. Conversely, alagomyid rodents, arctostylopids, prodinoceratids, tillodonts and coryphodontids are thought to have originated in Asia and to have subsequently dispersed into North America during the Gashatan ( Schoch and Lucas, 1985; Meng et al., 1994; Beard, 1998; Secord et al., 2006) . The Gashatan is thus characterised by an important and significant exchange of mammals between Asia and North America in both di鄄 rections (Fig. 3A) . ...
Recent research has greatly increased the information available on Asian Paleocene and early Eocene mammal faunas, creating the need to update the existing Asian biochronological and biogeographical framework. Based on a quantitative and qualitative analysis, biochronological boundaries are refined to correspond to major faunal turnovers, and an improved age correlation and biogeography of the Paleocene and early Eocene Asian Land Mammal Ages (ALMAs) is proposed. The poorly known Shanghuan ALMA is characterised as an assemblage dominated by primitive gliriforms and pantodonts. The following Nongshanian ALMA shows an endemic diversification of Asian mammals. Gliriforms radiated, with the appearance of new basal gliriforms and the first appearance of true Glires. The Shanghuan/Nongshanian boundary has been correlated to the Torrejonian/Tiffanian boundary in North America, and it is suggested here that the faunal turnover was possibly triggered by the start of a period of global cooling. The following Gashatan ALMA witnesses a further diversification and an abrupt reduction of the endemism of Asian mammals. Multituberculates, nyctitheriids, cimolestids and carpolestids appeared in the Gashatan faunas and represent North American immigrants. Conversely, a first wave of Asian mammals consisting of arctostylopids and prodinoceratids invaded North America at the start of Tiffanian-5a, and a second wave consisting of rodents, tillodonts and coryphodontids arrived in North America at the beginning of the Clarkforkian. The start of the Gashatan is therefore correlated with the start of North American Tiffanian-5a. The start of the Bumbanian ALMA is marked by the first appearance of artiodactyls, perissodactyls and true primates, similar to their appearance in North America and Europe at the start of the Eocene, and is correlated to the Paleocene-Eocene boundary. Contrasting with dispersal at the start of the Gashatan, dispersal during the Bumbanian seems to have been possible during a more extended period, and was also possible directly between Asia and Europe.
... Recent phylogenetic analyses support the monophyly of Xenungulata and Carodniidae, while Etayoidae are potentially paraphyletic (Antoine et al., 2015;Gelfo et al., 2020). However, the phylogenetic position and relationships of Xenungulata and even Carodnia have not a broad consensus among specialists (e.g., Gingerich, 1985;Schoch & Lucas, 1985;Villarroel, 1987;Cifelli, 1993;Lucas, 1993;O'Leary et al., 2013;Muizon et al., 2015). ...
... The relationship of Xenungulata is controversial and no consensus has been achieved. Schoch and Lucas (1985) proposed a close relationship between Carodnia (so far, the only known species of the order) and Dinocerata, nesting both in the non-ungulate mirorder Uintatheriamorpha. Bergqvist and Avilla (2003) consider the similarity in dental morphology between Xenungulata and Dinocerata a convergence between the two groups, as they present major differences in postcranial morphology. ...
... Despite of the lack of geological evidence, the idea of a landbridge connection during the Late Cretaceous/early Paleocene between Gondwana and Laurasia cannot be discounted, as biogeographical patterns presented by some terrestrial vertebrates (see Schoch & Lucas 1985;Muizon & Marshall 1992;Salgado &Calvo 1997) andplants (see Wang 1978;Hay et al. 1999) support the presence of such a connection. ...
Here we present new information on the oldest Xenarthra remains. We conducted a comparative morphological analysis of the osteoderms and postcranial bones from the Itaboraian (upper Paleocene) of Brazil. Several osteoderms and isolated humeri, astragali, and an ulna, belonging to at least two species, compose the assemblage. The bone osteoderms were assigned to Riostegotherium yanei Oliveira & Bergqvist, 1998, for which a revised diagnosis is presented. The appendicular bones share features with some "edentate" taxa. Many of these characters may be ambiguous, however, and comparison with early Tertiary Palaeanodonta reveals several detailed, derived resemblances in limb anatomy. This suggests that in appendicular morphology, one of the Itaboraí Xenarthra may be the sister-taxon or part of the ancestral stock of Palaeanodonta. © Publications Scientifiques du Muséum national d'Histoire naturelle, Paris.
Alcidedorbignya inopinata Muizon and Marshall is a primitive pantodont from the Early Paleocene of Tiupampa, Department of Cochabamba, in the “Cordillera Oriental” of south-central Bolivia. It is known by almost complete upper and lower dentitions, which are described in detail. The occurrence of abundant juvenile specimens allows a study of tooth replacement. The molars of Alcidedorbignya inopinata are primitive for a pantodont but they show the characteristic synapomorphy of the group, which is the presence of a V-shaped ectoloph of P3-4. However, the paracone and the metacone of A. inopinata are separated at their bases, a feature absent in the Bemalambdidae and Harpyodus , which have connate to semi-connate paracone and metacone. Because of this character, A. inopinata , although the oldest, is not the most primitive pantodont. However, A. inopinata , as in bemalambdids and Harpyodus , does not have a mesostyle on M1-2/ or a strongly V-shaped centrocrista, which are found in all other pantodonts. For this reason, Alcidedorbignya inopinata is removed from the Pantolambdidae (which are too specialized) and referred to the new monotypic family Alcidedorbignyidae. The family Wangliidae Van Valen, 1988, is not accepted here and the genus Wanglia is regarded as a junior synonym of Harpyodus ; the latter includes the two species H. euros and H. decorus. Analysis of pantodont origins leads to the conclusion that didelphodontines constitute the best potential sister-group; however, no synapomorphy could be found to substantiate this hypothesis. Alcidedorbignya inopinata is the first pantodont known from a southern continent and, being the oldest, it raises a discussion on the paleobiogeographic history of the group.
New material on the genus Gobiatherium is described from the Middle Eocene of Kyrgyzstan. It includes two almost complete skulls and a lower jaw including permanent and deciduous incisors. The cranial and dental morphology of Gobiatherium mirificum is considered. Based on these data, jaw muscle function is analyzed. The phylogenetic relationships of the Dinocerata and Pantodonta and the composition of the order Amblypoda are considered. The data on the historical development and geological and geographical distribution of these groups are analyzed. A hypothesis for the early isolation of amblypods from the eutherian stock is proposed.
The problem of relationships between the order Hyracoidea and the other orders assigned to the Ungulata sensu lato is considered. The history of studies and present views on the problem are reported. Skulls of the members of three orders presumably related to hyraxes, the Perissodactyla, Proboscidea, and Sirenia, were examined and described using comparative analysis. The data were used for a preliminary phylogenetic analysis that corroborated the previous hypothesis proposing close relationships between proboscideans, sirenians, and hyraxes. In accordance with available data, a revision of the macrotaxa within the Ungulata sensu lato is performed and the phylogenetic scheme for their adaptive radiation is proposed.
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