PDF(Pubmed)
Abstract：
Skulls of living whales and dolphins (cetaceans) are telescoped-bones of the skull roof are overlapped by expanded facial bones and/or anteriorly extended occipital bones. Evolution of the underlying skull roof (calvarium), which lies between the telescoped regions, is relatively unstudied. We explore the evolution and development of the calvarium of toothed whales (odontocetes) by integrating fetal data with Oligocene odontocete fossils from North America, including eight neonatal and juvenile skulls of Olympicetus†. We identified two potential synapomorphies of crown Cetacea: contact of interparietals with frontals, and a single anterior median interparietal (AMI) element. Within Odontoceti, loss of contact between the parietals diagnoses the clade including Delphinida, Ziphiidae and Platanistidae (=Synrhina). Delphinida is characterized by a greatly enlarged interparietal. New fetal series of delphinoids reveal a consistent developmental pattern with three elements: the AMI and bilateral posterior interparietals (PIs). The PIs most resemble the medial interparietal elements of terrestrial artiodactyls, suggesting that the AMI of cetaceans could be a unique ossification. More broadly, the paucity of conserved anatomical relationships of the interparietals, as well as the fact that the elements often do not coalesce into a single bone, demonstrates that assessing homology of the interparietals across mammals remains challenging. This article is part of the theme issue \'The mammalian skull: development, structure and function\'.
摘要：
活着的鲸鱼和海豚（鲸目动物）的头骨是可伸缩的，头骨屋顶的骨骼被扩展的面部骨骼和/或向前扩展的枕骨重叠。下层头骨屋顶（颅骨）的演变，位于望远镜区域之间，是相对未研究的。我们通过将胎儿数据与北美的渐新世齿科化石进行整合，探索齿鲸（齿科）的颅骨的进化和发展，包括奥利皮埃特的八个新生儿和少年头骨。我们确定了冠鲸的两个潜在的突触形态：冠间与正面的接触，和单个前正中顶间（AMI）元件。在Odontoceti内，顶楼之间失去联系可以诊断包括Delphinida在内的进化枝，Ziphiidae和Platanistidae（=Synrhina）。Delphinida的特征是顶间大大扩大。新的胎儿类蝶骨系列揭示了具有三个要素的一致发育模式：AMI和双侧后胎间（PI）。PI最类似于陆地偶蹄动物的内侧顶间元素，这表明鲸目动物的AMI可能是一种独特的骨化。更广泛地说,层间保守的解剖关系的缺乏，以及元素通常不会合并成单个骨骼的事实，表明评估哺乳动物间的同源性仍然具有挑战性。这篇文章是主题问题的一部分\'哺乳动物的头骨:发展,结构和功能。
