A new genus and species of sabretooth, Oriensmilus liupanensis (Barbourofelinae, Nimravidae, Carnivora), from the middle Miocene of China suggests barbourofelines are nimravids, not felids

Since the early 2000s, a revival of a felid relationship for barbourofeline sabretooths has become popular due to recent discoveries of fragmentary fossils from Africa. According to this view, barbourofelines trace their common ancestor with felids through shared similarities in dental morphology going back to the early Miocene of Africa and Europe. However, whether or not such an idea is represented in the basicranial morphology, a conservative area of high importance in family-level relationships, is yet to be tested. A nearly complete skull of Oriensmilus liupanensis gen. and sp. nov. from the middle Miocene Tongxin Basin of northern China represents the most primitive known barbourofeline with an intact basicranial region, affording an opportunity to re-examine the relationship of felids and nimravines. We also present an update on East Asian records of barbourofelines. The new skull of Oriensmilus possesses a suite of characters shared with nimravines, such as the lack of an ossified (entotympanic) bullar floor, absence of an intrabullar septum, lack of a ventral promontorial process of the petrosal, presence of a small rostral entotympanic on the dorsal side of the caudal entotympanic, and a distinct caudal entry of the internal carotid artery and nerve that pierces the caudal entotympanic at the junction of the ossified and unossified caudal entotympanics. The absence of an ossified bullar floor in O. liupanensis and its presence in those from the middle Miocene of Sansan, France thus help to bracket the transition of this character, which must have happened in the early part of the middle Miocene. Spatial relationships between bullar construction and the middle ear configuration of the carotid artery in Oriensmilus strongly resemble those in nimravines but are distinctly different from felids and other basal feliforms. Despite the attractive notion that early barbourofelines arose from a Miocene ancestor that also gave rise to felids, the basicranial evidence argues against this view. http://zoobank.org/urn:http://lsid:zoobank.org:pub:2DE98DBC-4D02-4E18-9788-0B0D8587E73F

自21世纪初以来，因非洲陆续出土的破碎化石材料，关于巴博剑齿虎亚科（Barbourofelinae）与猫科动物（Felidae）亲缘关系的重新探讨逐渐受到关注。根据该假说，巴博剑齿虎亚科与猫科动物的共同祖先可追溯至非洲与欧洲的中新世早期（early Miocene），二者共享牙齿形态学（dental morphology）上的诸多相似特征。然而，这一观点是否契合颅底形态学（basicranial morphology）——这一科级分类关系研究中兼具保守性与重要性的特征维度——尚未得到实证检验。
产自中国北方中新世中期（middle Miocene）同心盆地（Tongxin Basin）的宁夏东方剑齿虎（Oriensmilus liupanensis gen. et sp. nov.）近乎完整的头骨，是目前已知保存有完整颅底区域的最原始巴博剑齿虎亚科物种，为重新探讨猫科动物与猎猫科（Nimravidae）的亲缘关系提供了关键契机。本研究同时更新了东亚地区巴博剑齿虎亚科的化石记录。
该新发现的头骨具备一系列与猎猫科共有的衍生特征：无骨化的内鼓骨（entotympanic）鼓室底、缺失鼓室内隔（intrabullar septum）、无岩骨（petrosal）腹侧岬突（ventral promontorial process）、在后内鼓骨（caudal entotympanic）背侧存在小型前内鼓骨（rostral entotympanic），以及颈内动脉（internal carotid artery）与相关神经经骨化与未骨化的后内鼓骨连接处穿过后内鼓骨的独特后向入口。
宁夏东方剑齿虎缺乏骨化的鼓室底，而法国桑桑（Sansan）中新世中期的巴博剑齿虎标本则具备该性状，二者的对比为该特征的演化过渡提供了时间约束框架，该过渡应发生于中新世中期早期。宁夏东方剑齿虎的鼓室结构与颈内动脉中耳（middle ear）构型的空间关系，与猎猫科高度相似，但与猫科动物及其他基干猫型总科（basal feliforms）类群存在显著差异。
尽管"早期巴博剑齿虎源自同时孕育猫科动物祖先的中新世类群"这一假说颇具吸引力，但颅底形态学证据并不支持该观点。
http://zoobank.org/urn:http://lsid:zoobank.org:pub:2DE98DBC-4D02-4E18-9788-0B0D8587E73F