A new Cretaceous Metatherian mammal from Henan, China

Abstract

We report a new deltatheroidan mammal from the Upper Cretaceous of Henna, China. The new taxon, Lotheridium mengi, is based on a nearly complete skull and associated lower jaws with full adult dentition. Deltatheroidans are known mostly from fragmentary specimens from Asia and North America. Previous views on deltatheroidan relationships were diverse, but recent studies favored their metatherian affinity. The new specimen represents the most complete skull known for deltatheroidans and provides additional evidence that deltatheroidans already had the distinctive metatherian dental formula and replacement pattern and several other derived metatherian features, supporting the metatherian status for this clade. The new species also indicates that deltatheroidan mammals were more diverse and had broader geographical distributions than previously thought.

A large carnivorous mammal from the Late Cretaceous and the North American origin of marsupials

“…To understand the impact of these new data, we performed a parsimony analysis of dental and craniomandibular characters (Supplementary Note 2) scored for 48 metatherians and closely related taxa910. For the first time, all relevant Cretaceous and Palaeogene metatherian taxa known by relatively complete skulls were included in the same data matrix (Supplementary Data 1).…”

“…The data matrix was mainly derived from Rougier et al 21050. but with modifications and additions from other previous studies9115152 and this study. On the basis of the new craniodental material, we updated the scores of Didelphodon for 41 characters in the matrix; 34 were previously unknown (?)…”

“…Unfortunately, skulls of early metatherians are scarce and distributed unevenly across time, space and phylogeny. Of the 69 Cretaceous species, relatively complete skulls have been described for only four Asiatic taxa, all phylogenetically distant from the origin of marsupials49. The 60 species from North America (NA) are known almost exclusively from teeth and fragmentary jaws4.…”

Systematic affinities of the extinct metatherian Eobrasilia coutoi Simpson, 1947, a South American Early Eocene Stagodontidae: implications for "Eobrasiliinae"

“…Despite the presence of an oblique oriented and singlerooted P1 in Lotheridium mengi (Bi et al, 2015), this taxon does not show any inflation of the premolars, present a visible retro-premolar space separating P1 from P2, and undoubtedly differs from Marsupialiformes based on its dental morphology. The P1 is relatively larger than the one of Stagodontidae, Gaylordia, Didelphopsis and Malleodectes (Figure 6).…”

“…These cusps are developed and visible even in worn teeth. The P1 of Didelphopsis (Paula Couto, 1962), Gaylordia (Oliveira & Goin, 2015), Szalinia (Muizon & Cifelli, 2001), Herpetotherium (Fox, 1983), Acyon (Forasiepi et al, 2006), Roberthoffstetteria (Muizon, 1992) and Lotheridium (Bi et al, 2015) do not present developed anterior and posterior cusps. Similar accessory cusps are also present on the upper premolars of Didelphidae and Sparassocynidae (Reig et al, 1987); however, the phylogenetic analysis did not recover these morphologies as homologous (228:1).…”