Evidence for a single loss of mineralized teeth in the common avian ancestor
Evidence for a single loss of mineralized teeth in the common avian ancestor
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DOI：
10.1126/science.1254390
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发表时间：
2014-12-12
期刊：
影响因子：
56.9
通讯作者：
Springer, Mark S.
中科院分区：
文献类型：
--
作者：
Meredith, Robert W.;Zhang, Guojie;Springer, Mark S.
无牙症，即没有牙齿，在脊椎动物中逐渐进化，包括鸟类，海龟和几种哺乳动物。现代鸟类（新鸟类）使用角质的喙（rhamphotheca）和肌肉发达的砂囊来获取和处理食物。我们对几乎所有现存鸟类目的谱系进行了比较基因组分析，并在其他脊椎动物物种牙齿的牙釉质和牙本质中表达的基因中恢复了共享的失活突变，这表明现代鸟类的共同祖先缺乏矿化牙齿。我们估计牙齿脱落，或者至少是提供矿化牙齿外层的釉质帽的脱落，发生在大约1.16亿年前。
Edentulism, the absence of teeth, has evolved convergently among vertebrates, including birds, turtles, and several lineages of mammals. Instead of teeth, modern birds (Neornithes) use a horny beak (rhamphotheca) and a muscular gizzard to acquire and process food. We performed comparative genomic analyses representing lineages of nearly all extant bird orders and recovered shared, inactivating mutations within genes expressed in both the enamel and dentin of teeth of other vertebrate species, indicating that the common ancestor of modern birds lacked mineralized teeth. We estimate that tooth loss, or at least the loss of enamel caps that provide the outer layer of mineralized teeth, occurred about 116 million years ago.