A comparative study of cranial osteogenesis in turtles: implications for the diversification of skull morphology
A comparative study of cranial osteogenesis in turtles: implications for the diversification of skull morphology
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海龟颅骨成骨的比较研究：对颅骨形态多样化的影响
DOI：
10.1007/s00435-021-00544-2
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发表时间：
2021
期刊：
影响因子：
1
通讯作者：
Kitayama Chiyo
中科院分区：
文献类型：
--
作者：
Tokita Masayoshi;Watanabe Takumi;Sato Hiromu;Kondo Satomi;Kitayama Chiyo
爬行动物头骨的形态是高度多样化的，大致分为三种结构模式：Anapsid，Synapsid和Dapsid。在基础爬行动物和海龟身上都观察到了颞区完全被骨头覆盖的Anapsid情况。根据最近的系统发育研究，海龟是由潜伏类爬行动物进化而来的，这意味着海龟的颞窗是次要关闭的。尽管甲鱼颅骨颞区皮肤颅骨减少的反复进化以及驱动甲鱼颅骨进化的生物力学因素已经被积极地讨论，但其对甲鱼颅骨的发育基础仍然知之甚少。为了探讨甲鱼头骨形态进化的发育机制，我们描述了三种不同头骨形态的隐甲鱼的颅骨发生：陆龟(陆龟科)、毛龟(陆龟科)和中华龟甲(甲科)。我们对胚胎颅骨发生的种间比较表明，在隐甲鱼胚胎发生过程中，颅骨元素的生长模式被认为是高度保守的。我们发现，构成颅骨颞区的五种皮肤-颅骨元素(顶骨、后颅骨、Jugal、四颈静脉和鳞片)的生长模式在海龟物种之间高度保守，并且海龟头骨的形态多样性源于生长模式的细微差异。我们的研究还表明，海龟成体头骨的种间形态差异可能在孵化后的生长期变得明显，而不是在胚胎发育期间。
Reptilian skull morphology is highly diverse and broadly categorized into three architectural patterns: anapsid, synapsid, and diapsid. The anapsid condition where the temporal region is completely roofed by bones is observed in both basal reptiles and turtles. According to recent phylogenetic studies, turtles are derived from diapsid reptiles, implying that the temporal fenestrae were secondarily closed in turtles. Although the repeated evolution of dermatocranial bone reductions in the skull’s temporal region of the anapsid skull and the biomechanical factors driving the evolution of the anapsid skull in turtles have been actively discussed, its developmental basis for the anapsid skull remains poorly understood. To investigate the developmental mechanisms underlying the morphological evolution of turtle skulls, here we describe the cranial osteogenesis of three cryptodiran turtle species with distinct skull morphologies:Chelonia mydas(Cheloniidae),Mauremys reevesii(Geoemydidae), andPelodiscus sinensis(Trionychidae). Our interspecific comparison of embryonic cranial osteogenesis suggests that the growth pattern of skull bone elements is presumed to be highly conserved during embryogenesis across cryptodiran turtles. We found that the growth pattern of the five dermatocranial elements that construct the temporal region of the skull (the parietal, postorbital, jugal, quadratojugal, and squamosal) is highly conserved among turtle species, and that the morphological diversity of turtle skulls arises from slight differences in growth patterns. Our study also suggests that interspecific morphological differences in the cheloniid adult skulls may become apparent in the post-hatching growth period rather than during embryogenesis.