A Dorcatherium (Mammalia, Ruminantia, Middle Miocene) petrosal bone and the tragulid ear region

A petrosal bone from the French Middle Miocene locality Sansan is described. It belongs to the tragulid species Dorcatherium crassum. Using high-resolution X-ray computed tomography, we scanned this petrosal bone and segmented its embedded bony labyrinth. We compared the morphological data with those of three living Tragulidae: Tragulus javanicus, Hyemoschus aquaticus, and Moschiola meminna. We ran a phylogenetic analysis where fossil and extant pecoran ruminants were included to understand the distribution of characters of the petrosal bone and bony labyrinth within ruminants. We propose a set of new synapomorphies for the Tragulidae among the Ruminantia, including the absence of the basicapsular groove, a knob-shaped mastoid region, a knob anterior to the subarcuate fossa on the petrosal bone, a high number of cochlea turns, the dorsal insertion of the posterior limb of the lateral semicircular canal, the extension of the lateral semicircular canal beyond the plane of the posterior semicircular canal in dorsal view, and a pouch-like endolymphatic sac on the bony labyrinth. The clade constituted by Tragulus and Moschiola is confirmed by new synapomorphies such as a double convexity of the promontorium and a large pouch-like endolymphatic sac that covers the common crus. We demonstrate the potential of characters of the bony labyrinth for the phylogeny of ruminants. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Mennecart, B., and L. Costeur. 2016. A Dorcatherium (Mammalia, Ruminantia, Middle Miocene) petrosal bone and the tragulid ear region. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1211665.

本文记述了一件采自法国中新世中期桑桑（Sansan）产地的颞骨岩部（petrosal bone），其隶属于鼷鹿科（Tragulidae）的厚额鼷鹿（Dorcatherium crassum）。我们采用高分辨率X射线计算机断层扫描（high-resolution X-ray computed tomography）对该颞骨岩部进行扫描，并对其内部包埋的骨迷路（bony labyrinth）进行了分割。我们将该标本的形态学数据与现生3种鼷鹿科动物的数据进行了对比，分别为鼷鹿（Tragulus javanicus）、水鼷鹿（Hyemoschus aquaticus）与斑鼷鹿（Moschiola meminna）。我们开展了系统发育分析，纳入化石与现生的反刍类有角下目类群，以阐明颞骨岩部与骨迷路的性状在反刍类中的分布格局。我们为反刍亚目中的鼷鹿科提出了一系列全新的共衍征（synapomorphies），具体包括：基囊沟（basicapsular groove）缺失、乳突区呈结节状、颞骨岩部弓下窝（subarcuate fossa）前方具结节、耳蜗旋转圈数较多、外半规管后肢的背侧附着、背侧视角下外半规管延伸至后半规管平面之外，以及骨迷路内具囊状内淋巴囊（endolymphatic sac）。由鼷鹿属与斑鼷鹿属构成的支系（clade），可通过新的共衍征得到验证，这些共衍征包括：鼓岬（promontorium）具双凸形态，以及覆盖总脚（common crus）的大型囊状内淋巴囊。本研究证实了骨迷路性状在反刍类系统发育研究中的应用潜力。
补充数据——本文的补充材料可于www.tandfonline.com/UJVP免费获取。
本文引用格式：Mennecart, B. 与 L. Costeur，2016年。《厚额鼷鹿（哺乳纲、反刍亚目、中新世中期）的颞骨岩部与鼷鹿科耳部区域》。《脊椎动物古生物学杂志》（Journal of Vertebrate Paleontology）。DOI: 10.1080/02724634.2016.1211665。