The Platanistoidea is a large superfamily of odontocetes whose sole surviving member is Platanista gangetica, the Ganges river dolphin. Despite the diversity of the Platanistoidea, it remains poorly understood and in need of revision. As one of the earliest-diverging clade of crown odontocetes, understanding their distribution, morphology, and phylogeny is crucial to understanding the radiation of archaic odontocetes in the late Oligocene to the middle Miocene. Here we describe an archaic odontocete, named Perditicetus yaconensis, gen. et. sp. nov., from the latest Oligocene–earliest Miocene Nye Formation in Oregon. Perditicetus yaconensis, represented by the holotype USNM 335224, possesses several synapomorphies of the Platanistoidea. Intriguingly, strong morphological similarities exist between P. yaconensis and other archaic odontocetes in the ‘Chilcacetus clade’ especially in the vertex and pterygoid region. However, the results of our phylogenetic analyses failed to capture any phylogenetic relationships between Perditicetus and Chilcacetus. In this analysis, P. yaconensis is sister taxon to the clade Allodelphinidae + Squalodelphinidae + Platanistidae and we consider that P. yaconensis is one of the basal-most derived platanistoids. The type locality of the holotype specimen, in the Nye Formation, provides a window into the diversity of archaic odontocetes, especially platanistoids, during the latest Oligocene to earliest Miocene.

http://zoobank.org/urn:lsid:zoobank.org:pub:9B370DA2-8035-4A12-929C-D8FCA84438AE

Platanistoidea是一个大型的齿形动物超家族，其唯一的幸存成员是恒河豚Platanista gangetica。尽管Platanistoidea千差万别，但它仍然知之甚少，需要修改。作为最早的冠突齿动物进化分支之一，了解它们的分布，形态和系统发育对了解渐新世晚期至中新世中期的古老齿齿动物的辐射至关重要。在这里，我们描述了一种古老的齿齿动物，名为Perditicetus yaconensis，gen。等。sp。十一月，摘自俄勒冈州最新的渐新世-最早的中新世奈伊组。雅康柏由整体型USNM 335224代表的Platanistoidea具有数种同形。有趣的是，在“ Chicacetus进化枝”中，特别是在顶点和翼状region肉中，P。yaconensis和其他古老的齿形突科之间存在很强的形态相似性。但是，我们的系统发育分析结果未能反映出Perditicetus和Chilcacetus之间的任何系统发育关系。在此分析中，P。yaconensis是进化枝Allodelphinidae + Squalodelphinidae + Platanistidae的姊妹分类群，我们认为P. yaconensis是最衍生的基底扁桃体之一。Nye组中完整样标本的类型局部性为了解最新渐新世至最早的中新世期间古牙形突科，尤其是platanistoids的多样性提供了一个窗口。

http://zoobank.org/urn:lsid:zoobank.org:pub:9B370DA2-8035-4A12-929C-D8FCA84438AE