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首页> 外文期刊>American Museum Novitates >A review of the Mongolian cretaceous Dinosaur Saurornithoides (Troodontidae: Theropoda)
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A review of the Mongolian cretaceous Dinosaur Saurornithoides (Troodontidae: Theropoda)

机译：蒙古白垩纪恐龙Saurornithoides的综述（斜纹夜蛾科：Theropoda）

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摘要

We review the morphology, taxonomy, and phylogenetic relationships of the upper Cretaceous Mongolian troodontid Saurornithoides. Saurornithoides mongoliensis is known only by the holotype from Bayan Zag, Djadokhta Formation. This specimen includes a nearly complete, but weathered, skull and mandibles, a series of dorsal, sacral, and caudal vertebrae, and a partial pelvic girdle and hind limb. Saurornithoides junior, here referred to Zanabazar, also is known only by the holotype from Bugiin Tsav, Nemegt Formation. This specimen consists of a skull and partial mandible, a series of sacral and caudal vertebrae, a partial pelvic girdle, and the distal part of the right hind limb. Saurornithoides+Zanabazar is one of the few Mongolian taxa known from both the Djadokhta and Nemegt formations. The monophyly of Saurornithoides+Zanabazar has not been seriously questioned historically, yet empirical support for this clade is currently tenuous. A privileged phylogenetic relationship between Saurornithoides, Zanabazar, and the North American troodontid Troodon formosus is supported by numerous characters including the presence of a subotic recess, lateroventrally projecting and hollow basipterygoid processes, a lacrimal whose anterior process is significantly longer than its posterior process, a highly pneumatized parasphenoid rostrum, a constricted neck of the occipital condyle, a symphyseal region of the dentary that is slightly recurved medially, and an obturator process located near the middle of the ischiadic shaft. CT data for the skulls of both species facilitated a description of the endocranial anatomy of Saurornithoides mongoliensis and Zanabazar junior, including a reconstruction of the endocranial space of Zanabazar junior. Despite being the largest of the known troodontid species, the endocranial volume of Zanabazar junior is considerably smaller than that estimated for Troodon formosus, suggesting that the extremely high encephalization quotient of Troodon formosus may be autapomorphic among troodontids.
机译：我们回顾了上部白垩纪蒙古troodontid Saurornithoides的形态，分类学和系统发育关系。蒙古Saurornithoides仅通过来自Djadokhta组的Bayan Zag的全型才知道。该标本包括几乎完整但风化的颅骨和下颌骨，一系列背，骨和尾椎骨，以及部分骨盆带和后肢。初中的Saurornithoides，这里称为Zanabazar，也仅由Nemegt组的Bugiin Tsav的整型已知。该标本由头骨和下颌骨，一系列骨和尾椎骨，部分骨盆带和右后肢的远端部分组成。 Saurornithoides + Zanabazar是从Djadokhta和Nemegt地层中已知的少数蒙古分类群之一。历史上没有对Saurornithoides + Zanabazar一夫一妻制提出过严肃的质疑，但是目前对这种进化枝的经验支持很微弱。 Saurornithoides，Zanabazar和北美troodontid Troodon formosus之间的特权系统发育关系受到众多特征的支持，包括亚隐性隐窝，后腹突出和空心的棘突，这是一种泪腺，其前突比其后突明显长。高度气化的副蝶骨讲台，枕骨dy的neck缩颈部，略微向内弯曲的齿状牙结膜区域以及位于坐骨干中间的闭孔突。两种物种的颅骨的CT数据都有助于描述蒙古蜥和小Zanabazar的颅内解剖结构，包括重建小Zanabazar的颅内空间。尽管Zanabazar junior的已知颅内齿种最大，其颅内体积却比Troodon formosus的估计要小得多，这表明Troodon formosus的极高脑化商可能是拟齿的。

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