Vertebrate dentitions at the origin of jaws: when and how pattern evolved
Vertebrate dentitions at the origin of jaws: when and how pattern evolved
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DOI：
10.1046/j.1525-142x.2003.03047.x
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发表时间：
2003-07-01
影响因子：
2.9
通讯作者：
Smith, MM
中科院分区：
文献类型：
--
作者：
Smith, MM
新的证据表明，牙齿的进化比以前认为的更大程度上独立于颌骨。无颌鱼类、早期有颌鱼类和早期有颌鱼类的前颌牙齿都有咽齿。许多这些dennalus形式加入两极集在每个鳃弓;这些类似于螺纹状齿套上的颌骨干和冠nathostomes和建议作为同源单位。因此，这些咽齿和齿组的图案来源是从无颌条件下保存下来的。据建议，发育监管系统，负责所有这些牙齿模式的颌骨，增选从咽部区域，而不是从皮肤的经典理解。这强烈暗示胚胎内胚层，而不是外胚层在遗传控制的齿列图案。提出了新的解释的个体发育数据的模式齿现存的鲨鱼，连同那些osteichthyan鱼。根据一种新的模式，重新评价了位于有颌类化石发生基础上的两个完整的化石群，盾皮类和棘皮类。它的结论是，在干组和冠组gnathostomes几个不同的策略，独特的每个分类群，通过产生不同的发展模式的齿列图案从咽denomial。一个共同的发展模式是从原始牙齿网站，独立地在每个牙齿区的颌骨。新的模型被提出作为进化发育遗传学数据的框架。
New evidence shows that teeth evolved with a greater degree of independence from jaws than previously considered. Pharyngeal denticles occur in jawless fish and also in early gnathostomes and precede jaw teeth in phylogeny. Many of these denticles form joined polarized sets on each branchial arch; these resemble whorl-shaped tooth sets on the jaws of stem and crown gnathostomes and are proposed as homologous units. Therefore, the source of patterning of these pharyngeal denticle and tooth sets is conserved from jawless conditions. It is proposed that developmental regulatory systems, responsible for all such tooth patterns on the jaws, are co-opted from the pharyngeal region and not from the skin as classically understood. This strongly implicates embryonic endoderm as opposed to ectoderm in the genetic control of dentition patterning. New interpretations of ontogenetic data on patterning dentitions of extant sharks are proposed, together with those of osteichthyan fish. Two entirely fossil groups, placoderms and acanthodians, at the base of gnathostome phylogeny are reassessed on the basis of a new model. It is concluded that within stem group and crown group gnathostomes several different strategies, unique to each taxon, were adopted to produce different developmental models of dentition patterning from pharyngeal denticles. One shared developmental pattern is that of initiation from primordial tooth sites, independently in each dentate zone of the jaws. The new model is proposed as a framework for data on evolutionary developmental genetics.