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Evidence for a single loss of mineralized teeth in the common avian ancestor

12/19/2014

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Imagen
Time tree of edentulous and enamelless amniotes compiled from previous studies
Evidence for a single loss of mineralized teeth in the common avian ancestor
by R.W. Merideth, G. Zhang, et al.

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. 

Read the paper: Science.org
Source: rhamphotheca
La evidencia de la pérdida de dientes mineralizados en el ave como ancestro común por R. W. Merideth, G. Zhang, et al.

El endentulismo, la ausencia de dientes, ha evolucionado de manera convergente entre los vertebrados, incluyendo aves, tortugas y varios linajes de mamíferos. En lugar de dientes, las aves modernas (Neornithes) utilizan un pico córneo (rhamphotheca) y una molleja muscular para adquirir y procesar los alimentos.
Se realizaron análisis genómicos comparativos que representan linajes de órdenes de aves casi todos existentes, inactivando las mutaciones en los genes expresados tanto en el esmalte y la dentina de los dientes de otras especies de vertebrados, que indica que el ancestro común de las aves modernas carecía de dientes mineralizados.
Estimamos que la pérdida de dientes, o al menos la pérdida de tapas de esmalte que proporcionan la capa externa de los dientes mineralizados, se produjo hace aproximadamente 116 millones de años.
Lee el artículo: Science.org
Fuente: rhamphotheca
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