Tooth microwear and occlusal modes of euharamiyidans from the Jurassic Yanliao Biota reveal mosaic tooth evolution in Mesozoic allotherian mammals

‘Haramiyidans’ are extinct mammaliaforms often clustered with Multituberculata as Allotheria, and with a fossil record extending from the Upper Triassic to possibly the Upper Cretaceous. For many decades, ‘haramiyidans’ were known only from isolated teeth, and their relationships to other mammaliaforms remain unclear. With the discovery of several euharamiyidans represented by skeletal specimens from the Jurassic Yanliao Biota, north‐western China, our knowledge of this group has significantly advanced. Nonetheless, much morphology, including dentition and occlusal patterns, has only been briefly described for most taxa, and phylogenetic reconstruction and interpretation of the biology of the group still remain unclear or controversial. Here we provide systematic descriptions of the dental wear of shenshouids (Qishou and Shenshou) from the Yanliao Biota. We reconstruct the occlusal mode of shenshouids and compare it with those of other taxa based on our observation of specimens of most ...“哈勒姆兽类（Haramiyidans）”是一类已灭绝的哺乳形类，常与多瘤齿兽类（Multituberculata）一同被归入全兽类（Allotheria），其化石记录的时代跨度从三叠纪晚期延伸至可能的白垩纪晚期。数十年来，学界对“哈勒姆兽类”的认知仅局限于孤立出土的牙齿化石，其与其他哺乳形类的演化关系始终不明。随着中国西北侏罗纪燕辽生物群（Yanliao Biota）中多件真哈勒姆兽类（euharamiyidans）骨骼标本的发现，学界对该类群的认知得到了显著提升。尽管如此，多数类群的诸多形态学特征——包括齿列与咬合模式——仅得到了简要描述，该类群的系统发育重建以及生物学功能诠释仍存在诸多模糊与争议之处。本文对燕辽生物群中神兽类（shenshouids，包括七曙兽Qishou与神兽Shenshou）的牙齿磨损特征开展了系统性描述，重建了神兽类的咬合方式，并基于多数类群标本的观测结果，将其与其他类群的咬合模式进行了对比……