A new partial skeleton of Kryptobaatar from the Upper Cretaceous of Bayan Mandahu (Inner Mongolia, China) relaunch the question about variability in djadochtatherioid multituberculate mammals

A new well-preserved partial skeleton of the djadochtatheriid multituberculate Kryptobaatar is here described from the Campanian Bayan Mandahu Formation of the southern Gobi Basin in Inner Mongolia, China. We refer to it as Kryptobaatar sp. because it presents characters that are specific to Kryptobaatar dashzevegi and others specific to Kryptobaatar mandahuensis, as well as characters of its own. When those taxa are incorporated into a phylogenetic analysis of the Djadochtatherioidea, the Kryptobaatar species appear to be paraphyletic. This raises again questions about the high intraspecific variability in some multituberculates. Based on a comparison with the published specimens, we conclude that K. mandahuensis is a valid species, close to but distinct from K. dashzevegi. Our results also suggest that endemism alone in the Gobi Basin is not the cause of the high variability observed in the genus Kryptobaatar. But the impact of a possible difference in age or paleoenvironment between the different Kryptobaatar-bearing sites of the Gobi Desert is, for the moment, not possible to test in the current state of knowledge. (c) 2021 Elsevier Ltd. All rights reserved.