Paleontological Museum of Liaoning, Shenyang Normal University, Shenyang Liaoning 110034, China.
College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao, Shandong 266590, China.
Science. 2019 Jul 19;365(6450):276-279. doi: 10.1126/science.aau9345.
We report a new Jurassic docodontan mammaliaform found in China that is preserved with the hyoid bones. Its basihyal, ceratohyal, epihyal, and thyrohyal bones have mobile joints and are arranged in a saddle-shaped configuration, as in the mobile linkage of the hyoid apparatus of extant mammals. These are fundamentally different from the simple hyoid rods of nonmammaliaform cynodonts, which were likely associated with a wide, nonmuscularized throat, as seen in extant reptiles. The hyoid apparatus provides a framework for the larynx and for the constricted, muscularized esophagus, crucial for transport and powered swallowing of the masticated food and liquid in extant mammals. These derived structural components of hyoids evolved among early diverging mammaliaforms, before the disconnection of the middle ear from the mandible in crown mammals.
我们报道了一种在中国发现的新的侏罗纪始兽类哺乳形动物化石，该化石保存了舌骨。其基舌骨、茎舌骨、甲状舌骨和环状软骨具有活动关节，并呈鞍形排列，与现生哺乳动物舌骨器官的活动连接方式相同。这些与非哺乳形合弓类动物的简单舌骨棒根本不同，后者可能与宽阔的、非肌肉化的喉咙有关，如现生爬行动物那样。舌骨器官为喉和收缩的、肌肉化的食管提供了一个框架，对于现生哺乳动物咀嚼食物和液体的运输和有力吞咽至关重要。这些舌骨的衍生结构成分在中耳与颌骨分离之前，在早期分化的哺乳形动物中进化而来，而在有颌类中，中耳与颌骨已经分离。
