New material of Palaeoamasia kansui (Embrithopoda, Mammalia) from the Eocene of Turkey and a phylogenetic analysis of Embrithopoda at the species level

Abstract

Since the discovery of the megaherbivore Arsinoitherium zitteli Beadnell (early Oligocene of Egypt), the extinct order Embrithopoda has remained an enigmatic group, with disputed affinities among ungulates. In this study, new specimens of Palaeoamasia kansui from the early Palaeogene of Turkey are described and a synthetic dental terminology is proposed for embrithopods. Based on 130 cranial–mandibular and dental characters, the first phylogenetic analysis of embrithopods is carried out in aim to enhance the position of Palaeoamasia within embrithopods. The monophyly of Embrithopoda is confirmed, following the topology (Phenacolophus (Namatherium (Arsinoitheriinae, Palaeamasiinae))). However, phylogenetic relationships between Eurasian embrithopods (Palaeoamasiinae: Palaeoamasia, Crivadiatherium and Hypsamasia) remain unresolved. The integration of all embrithopod genera within a cladistic analysis encompassing a wider taxonomic sample (Condylarthra, Afrotheria/Paenungulata and Laurasiatheria) also supports Embrithopoda as being monophyletic, but questions the position of both Phenacolophus and Namatherium within Embrithopoda. Finally, possible faunal exchange events are proposed based on three hypothesized scenarios between Eurasia and Arabia–Africa during the early Palaeogene.

Early African Fossils Elucidate the Origin of Embrithopod Mammals

“…Our cladistic analysis supports the Embrithopoda monophyly [21]. The embrithopods distribution in both Arabo-Africa (Stylolophus, Arsinoitheriidae) and Eurasia (Palaeoamasiidae) [21,27] is the most demonstrative mammalian evidence of trans-Tethyan dispersals involving Africa ( Figure S2).…”

“…Our cladistic analysis supports the Embrithopoda monophyly [21]. The embrithopods distribution in both Arabo-Africa (Stylolophus, Arsinoitheriidae) and Eurasia (Palaeoamasiidae) [21,27] is the most demonstrative mammalian evidence of trans-Tethyan dispersals involving Africa ( Figure S2). The basal embrithopod position and early age of Stylolophus, as well as the supraordinal relationships to the Afrotheria/Paenungulata, all indicate at least an earliest Paleogene African center of origin for the Embrithopoda.…”

“…are regarded as successive chronospecies of a new Ypresian mammal lineage found in Ouled Abdoun series. The intraordinal relationships of other embrithopods remain poorly solved in our analysis, and especially for the poorly known palaeoamasiids Hypsamasia and Crivadiatherium, as previously found by Erdal et al [21]. It should be particularly noted that the node grouping the palaeoamasiids Hypsamasia and Crivadiatherium with arsinoitheriids, to the exclusion of Palaeoamasia (Figures 4A and 4B), relies mostly on character optimizations, and it is poorly supported with low Bremer support.…”

Evolutionary Models for the Diversification of Placental Mammals Across the KPg Boundary

“…For example, the entirely extinct Plesiadapiformes are generally recognized as a paraphyletic taxon at the base of Euprimates (Silcox et al, 2017), but some cladistic analyses with more comprehensive taxon sampling place the earliest known plesiadapiform genus, Purgatorius , outside of Placentalia (Halliday et al, 2017; Halliday et al, 2019). Similarly, Gheerbrant et al (2018) recovered the extinct order Embrithopoda as a clade of stem tethytheres, but other analyses have positioned this order elsewhere within Paenungulata or even deeper in Afrotheria (Tabuce et al, 2007; Cooper et al, 2014; Erdal et al, 2016). An even more difficult fossil group is Anagalida, which minimally includes the families Anagalidae and Pseudictopidae.…”

Küçük Memeli Paleontolojisinin Türkiye’deki Kuvaterner Çalışmalarına Katkısı: Tanımlar ve Uygulamalar

“…The Anatolia is considered as a bridge between Africa, Europe and Asia, and is known by its important role in the evolution of small and large mammals (Ünay, 1996;Sen 2013;Albayrak 2016;Erdal et al, 2016). Historically, first geographical and geological observations within the Ottoman Empire territories date back to 1800s, made by European explorers and researchers thanks to their "voyages d 'études" (e.g.…”