A new Oligo–Miocene marsupial lion from Australia and revision of the family Thylacoleonidae

Wakaleo schouteni sp. nov., a dog-sized marsupial lion (Thylacoleonidae), is described from late Oligocene to early Miocene sediments of the Riversleigh World Heritage Area, Queensland, Australia. Fossils of this new species include a near-complete cranium, dentaries and postcrania. This species is the second thylacoleonid known from late Oligocene sediments. The other, Priscileo pitikantensis Rauscher, 1987, from the Etadunna Formation of South Australia, is known from teeth, part of a palate and postcrania. Wakaleo schouteni exhibits cranial and dental morphology characteristic of species of Wakaleo but possesses a relatively plesiomorphic upper dental formula (i.e. three premolars and four molars) within Thylacoleonidae that was formerly regarded to be diagnostic for species of the genus Priscileo. The holotype and humerus of P. pitikantensis have been compared with the new Wakaleo material described here and found to demonstrate conspicuous similarities in morphology of the M2 and the humerus. In the absence of other generically diagnostic features, Priscileo is here regarded to be a junior synonym of Wakaleo. Smaller size and relatively minor morphological differences in the proximal humerus of W. pitikantensis comb. nov. distinguish it at the specific level from W. schouteni. Phylogenetic analysis of thylacoleonids recovers Wakaleo as a monophyletic clade. Both Wakaleo pitikantensis comb. nov. and W. schouteni are recovered as plesiomorphic sister taxa to other species of the genus. Wakaleo pitikantensis and W. schouteni extend the temporal range for this genus back into the late Oligocene. Body weight for W. schouteni, based on total skull length, is estimated to be ∼23 kg. http://zoobank.org/urn:lsid:zoobank.org:pub:CA8A8EC8-4F66-4F1E-81DC-240A0C4080BE

新种舒滕沃卡莱奥袋狮（Wakaleo schouteni sp. nov.）是一种体型与家犬相当的袋狮科（Thylacoleonidae）物种，其化石发现于澳大利亚昆士兰州里弗斯利世界遗产地的渐新世晚期至中新世早期沉积物中。该新种的化石标本涵盖近乎完整的颅骨、下颌骨与颅后骨骼。本种是目前已知第二种产自渐新世晚期地层的袋狮科物种，另一物种为1987年劳舍尔（Rauscher）发表的皮蒂坎特普里西莱奥袋狮（Priscileo pitikantensis Rauscher, 1987），其化石产自南澳大利亚埃塔敦纳组，仅包含牙齿、部分腭骨与颅后骨骼。舒滕沃卡莱奥袋狮具备沃卡莱奥属（Wakaleo）物种典型的颅骨与牙齿形态特征，但拥有袋狮科内相对祖征的上齿式（即3枚前臼齿与4枚臼齿）——该齿式此前被认为是普里西莱奥属（Priscileo）物种的专属鉴别特征。研究团队将皮蒂坎特普里西莱奥袋狮的正模标本（holotype）及肱骨与本次记述的沃卡莱奥新种标本进行比对后，发现二者在M2与肱骨形态上存在显著相似性。鉴于缺乏其他具有属级鉴别价值的形态特征，本次研究将普里西莱奥属认定为沃卡莱奥属的晚出同物异名。经新组合更名后的皮蒂坎特沃卡莱奥袋狮（W. pitikantensis comb. nov.）体型更小，且其肱骨近端存在相对细微的形态差异，因此可在种级分类水平上与舒滕沃卡莱奥袋狮相区分。针对袋狮科的系统发育分析（phylogenetic analysis）结果显示，沃卡莱奥属为一单系群（monophyletic clade）。皮蒂坎特沃卡莱奥袋狮与舒滕沃卡莱奥袋狮均为该属其余物种的祖征姊妹群（sister taxa）。皮蒂坎特沃卡莱奥袋狮与舒滕沃卡莱奥袋狮将沃卡莱奥属的生存时间跨度追溯至渐新世晚期。基于头骨总长度估算，舒滕沃卡莱奥袋狮的体重约为23千克。相关分类学注册信息：http://zoobank.org/urn:lsid:zoobank.org:pub:CA8A8EC8-4F66-4F1E-81DC-240A0C4080BE