Development and evolution of tooth renewal in neoselachian sharks as a model for transformation in chondrichthyan dentitions.
Development and evolution of tooth renewal in neoselachian sharks as a model for transformation in chondrichthyan dentitions.
复制标题
新鲨鱼牙齿更新的发育和进化作为软骨鱼类牙列转变的模型。
DOI：
10.1111/joa.12796
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发表时间：
2018
影响因子：
2.4
通讯作者：
Meredith Smith M
中科院分区：
文献类型：
--
作者：
Meredith Smith M
现代鲨鱼和鳐的齿系的一个定义特征是产生多个替换牙齿的规则模式顺序。这些排列在替换牙齿的唇舌文件中，这些替换牙齿在沿着颌和在深牙板中相继开始的牙齿内以连续的时间顺序形成。两种不同的成年人齿系已经被描述：交替的，其中新牙齿的时间在两个相邻的文件之间交替，每个文件单独萌出，另一个被安排为单个文件，其中每个文件的牙齿被定时一起萌出，在一些分类群中，促进类似定时的牙齿连接形成切割刀片。两者都依赖于时空调节的新牙齿形成。成年的天使鲨Squatina（Squalomorphii）的一个单一的文件齿列，但我们获得了新的数据的牙齿发育顺序的文件squatinaembryos，显示交替时间的牙齿开始。这是基于micro-CT扫描显示，最早的矿化牙齿在颌骨边缘和他们的替代文件对（奇数和偶数颌骨位置）交替在他们的开始时间。沿着的是对其他角鲨类的新观察，如六角鲨和衣原体鲨，以及姐妹群Galeomorphii的代表，已经确定了交替的牙齿模式（开始时间和替换顺序）是现存鲨鱼胚胎牙列的特征;然而，这在成年后可能会改变。这些字符的状态绘制到最近的发育，表明Squalomorphii显示出相当大的可塑性的牙齿发育。我们提出了一个发展-进化模型，以允许从替代牙齿的替代到单个文件对齐的变化。这建立了新的牙齿形态在成年鲨鱼从继承交替秩序。
A defining feature of dentitions in modern sharks and rays is the regulated pattern order that generates multiple replacement teeth. These are arranged in labio‐lingual files of replacement teeth that form in sequential time order both along the jaw and within successively initiated teeth in a deep dental lamina. Two distinct adult dentitions have been described: alternate, in which timing of new teeth alternates between two adjacent files, each erupting separately, and the other arranged as single files, where teeth of each file are timed to erupt together, in some taxa facilitating similarly timed teeth to join to form a cutting blade. Both are dependent on spatiotemporally regulated formation of new teeth. The adult Angel sharkSquatina(Squalomorphii) exemplifies a single file dentition, but we obtained new data on the developmental order of teeth in the files ofSquatinaembryos, showing alternate timing of tooth initiation. This was based on micro‐CT scans revealing that the earliest mineralised teeth at the jaw margin and their replacements in file pairs (odd and even jaw positions) alternate in their initiation timing. Along withSquatina, new observations from other squalomorphs such asHexanchusandChlamydoselachus, together with representatives of the sister group Galeomorphii, have established that the alternate tooth pattern (initiation time and replacement order) characterises the embryonic dentition of extant sharks; however, this can change in adults. These character states were plotted onto a recent phylogeny, demonstrating that the Squalomorphii show considerable plasticity of dental development. We propose a developmental‐evolutionary model to allow change from the alternate to a single file alignment of replacement teeth. This establishes new dental morphologies in adult sharks from inherited alternate order.