A new species of Metopocetus (Cetacea, Mysticeti, Cetotheriidae) from the Late Miocene of the Netherlands.
A new species of Metopocetus (Cetacea, Mysticeti, Cetotheriidae) from the Late Miocene of the Netherlands.
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作者：
Marx FG;Bosselaers ME;Louwye S
须鲸科在最近须鲸系统发育的讨论中发挥了重要作用。在这个类群中，神秘的、单型的硬地衣藻被解释为两栖类和其他家族成员之间的过渡，但到目前为止，仅限于一个单一的、不确定来源和年龄的碎裂头骨。在这里，我们扩展了该属，并通过描述Metopoctus Hunteri sp.对其系统发育亲缘关系和功能形态提供了新的线索。11月来自荷兰中新世晚期。与硬脊膜分枝杆菌的正型不同，这里描述的材料是自信的年代，并保存了鼓泡和颅底的额外细节。亨特氏分枝杆菌与硬脊膜分枝杆菌非常相似，主要不同之处在于其鼓膜后突的远端扩张较少。这两个物种的特征都是在枕旁突的腹面上发育出一个异常大的窝，它向前延伸到复合的后突，并完全填满面沟。在生活中，这个扩大的颅窝可能容纳了后鼻窦和/或茎舌关节。与其他鲸目动物一样，后生动物在上颌升突底部附近也有一个发育良好的、向后指向的眶下孔，其确切功能尚不清楚。
The family Cetotheriidae has played a major role in recent discussions of baleen whale phylogenetics. Within this group, the enigmatic, monotypic Metopocetus durinasus has been interpreted as transitional between herpetocetines and other members of the family, but so far has been restricted to a single, fragmentary cranium of uncertain provenance and age. Here, we expand the genus and shed new light on its phylogenetic affinities and functional morphology by describing Metopocetus hunteri sp. nov. from the Late Miocene of the Netherlands. Unlike the holotype of M. durinasus, the material described here is confidently dated and preserves both the tympanic bulla and additional details of the basicranium. M. hunteri closely resembles M. durinasus, differing primarily in its somewhat less distally expanded compound posterior process of the tympanoperiotic. Both species are characterised by the development of an unusually large fossa on the ventral surface of the paroccipital process, which extends anteriorly on to the compound posterior process and completely floors the facial sulcus. In life, this enlarged fossa may have housed the posterior sinus and/or the articulation of the stylohyal. Like other cetotheriids, Metopocetus also bears a well-developed, posteriorly-pointing dorsal infraorbital foramen near the base of the ascending process of the maxilla, the precise function of which remains unclear.