The origin of Rhinocerotoidea and phylogeny of Ceratomorpha (Mammalia, Perissodactyla)

Abstract

Rhinoceroses have been considered to have originated from tapiroids in the middle Eocene; however, the transition remains controversial, and the first unequivocal rhinocerotoids appeared about 4 Ma later than the earliest tapiroids of the Early Eocene. Here we describe 5 genera and 6 new species of rhinoceroses recently discovered from the early Eocene to the early middle Eocene deposits of the Erlian Basin of Inner Mongolia, China. These new materials represent the earliest members of rhinocerotoids, forstercooperiids, and/or hyrachyids, and bridge the evolutionary gap between the early Eocene ceratomorphs and middle Eocene rhinocerotoids. The phylogenetic analyses using parsimony and Bayesian inference methods support their affinities with rhinocerotoids, and also illuminate the phylogenetic relationships and biogeography of Ceratomorpha, although some discrepancies are present between the two criteria. The nearly contemporary occurrence of various rhinocerotoids indicates that the divergence of different rhinocerotoid groups occurred no later than the late early Eocene, which is soon after the split between the rhinocerotoids and the tapiroids in the early early Eocene. However, the Bayesian tip-dating estimate suggests that the divergence of different ceratomorph groups occurred in the middle Paleocene.

Adaptation to graviportality in Rhinocerotoidea? An investigation through the long bone shape variation in their hindlimb

“…Recent publications refined the phylogenetic relationships within Rhinocerotoidea (Wang et al, 2016;Tissier et al, 2018;Tissier, Antoine, & Becker, 2020;Bai et al, 2020) and within Ceratomorpha (Bai et al, 2020), although not including all genera of rhinocerotoids currently known worldwide.…”

“…To take into account the effect of phylogeny on shape variation, we constructed a composite cladogram using trees previously computed on cranio-dental and postcranial characters or molecular data. We reconstructed interspecific relationships, branch lengths and occurrence dates after the works of Cerdeño (1995), Antoine (2002), Antoine, Duranthon, & Welcomme (2003), Antoine et al (2010), Prothero (2005), Boada-Saña (2008), Piras et al (2010), Becker, Antoine, & Maridet (2013), Lu (2013), Wang et al (2016), Averianov et al (2017), Tissier et al (2018), Tissier, Antoine, & Becker (2020), Bai et al (2020). We used the cladistic framework of Antoine et al (2003) and Becker et al (2013) to define families, subfamilies, tribes and subtribes (Fig.…”

“…As previously mentioned, the phylogeny of Rhinocerotoidea remains debated for both extant and extinct taxa and is frequently renewed by the determination of new representatives (Tissier et al, 2020;Bai et al, 2020). Consequently, we assessed the effect of potential uncertainty in taxa position in the phylogeny on PGLS by using a Nearest Neighbour Interchange (NNI) procedure.…”

Guiclupea superstes, gen. et sp. nov., the youngest ellimmichthyiform (clupeomorph) fish to date from the Oligocene of South China

“…Kwangoclupea forms the sister group to Codoichthys and lies in a relatively basal position in the two SCTs, whereas it lies in a relatively derived position and belongs to the Paraclupeidae in the two BITs. These differences between the general topologies of the SCTs and BITs are probably due to the fact that the information contained in the dataset is insufficient to draw firm conclusions about their relationships as pointed out in the recent analyses of the phylogeny of Ceratomorpha (Bai et al, 2020). To improve the understanding of relationships of the group, more phylogenetically informative fossils and more complete data are needed.…”

“…The analyses use both parsimony and Bayesian inference methods, for both methods have advantages and disadvantages for morphological data ( Bai et al, 2020 ). The parsimony analyses were performed with TNT 1.5 ( Goloboff, Farris & Nixon, 2008 ), using the Traditional Search method with 1000 replicates and tree bisection and reconnection (TBR) swapping algorithm.…”