恐龙表亲也“下崽”——胎生助羊膜动物称霸海洋

Dinosaur Cousins that Gave Birth to Live Young Promoted Radiation of Marine Amniotes

2.45亿年前的一件海生爬行动物化石首次提供了胎生方式在主龙型爬行动物(包括灭绝的恐龙、现生的鸟类和鳄以及它们的祖先)中演化的证据。这一发现证实胎生方式和基因性别决定机制帮助羊膜动物称霸海洋。

Reptiles are generally taken as egg-laying animals. A recent discovery of fossil marine reptiles from South China shows the evidence of live birth and suggests that there was no genetic barrier for live birth in a group including crocodilians and birds. The result indicates that viviparity and genotypic sex determination together promoted the radiation of amniotes in the marine realm.