ABSTRACT

Desmatophocidae (Mammalia, Carnivora) represents the first of the four major pinniped clades to appear in the fossil record. However, the majority of its known diversity consists of derived species and little is known about the nascence of this early pinniped lineage. Here we report the discovery of Eodesmus condoni, gen. et sp. nov., represented by a nearly complete cranium from the Burdigalian Iron Mountain Bed of the Astoria Formation from the central coast of Oregon, U.S.A. Notably, this specimen possesses nasolabialis fossae, a plesiomorphic trait shared with stem pinnipedimorphs and the basal phocid Devinophoca sp., but not with any other desmatophocid. Phylogenetic analysis (98 characters, 27 taxa) resolved Eodesmus condoni as the most basal desmatophocid yet described. Poor support for the monophyly of Otarioidea, Odobenidae, and Phocoidea demonstrate that high-level relationships within Pinnipedia have yet to be conclusively resolved. The identification of another desmatophocid species at the already pinniped-rich Iron Mountain Bed suggests that the approximately synchronous mid-Miocene Climatic Optimum played a role in this increase in pinnipedimorph species diversity.

http://zoobank.org/urn:lsid:zoobank.org:pub:C9335617-3A0D-414A-937A-72C859C0075F

摘要

Desmatophocidae（食肉动物，哺乳动物）是化石记录中出现的四个主要的针刺进化枝中的第一个。但是，它的大多数已知多样性都是由衍生物种组成，而对于这种早期的nip夹世系的鼻腔知之甚少。在这里，我们报告了Eodesmus condoni gen的发现。等。十一月，由来自美国俄勒冈州中部海岸的阿斯托里亚岩层的布尔迪加利安铁山床的近乎完整的颅骨所代表。但不能与任何其他杀真菌剂一起使用。系统发育分析（98个字符，27个分类单元）解析出Eodesmus condoni作为迄今所描述的最基础的杀菌剂。对Otarioidea，Odobenidae和Phocoidea的一夫一妻制的支持不力表明Pinnipedia内的高级关系尚待最终解决。在已经富含pinnipedimorph物种多样性的发现中，在已富含pinnipedimorph物种的铁中山床中发现了另一种脱气菌科物种，这表明中新世中期气候最适同步。

http://zoobank.org/urn:lsid:zoobank.org:pub:C9335617-3A0D-414A-937A-72C859C0075F