Evolution of key biological characteristics in dinosaurs and their relatives

恐龙和它们的近亲，包括翼龙和鳄鱼，组成了爬行动物类群初龙。在中生代的大部分时间里，祖龙统治着大型陆生脊椎动物的生态位，而被称为鸟类的变异恐龙占了大约10,000个现存物种。主龙类的生物学特征必须有助于解释它们的成功，但主龙类生物学的许多方面只能在活的鸟类和鳄鱼身上直接研究。对于灭绝的祖龙，必须使用化石证据，与活动物的比较以及生物力学建模等方法进行推断。

Dinosaurs and their close relatives, including pterosaurs and crocodilians, comprise the reptilian group Archosauria. Archosaurs dominated large terrestrial vertebrate niches throughout most of the Mesozoic, and the modified dinosaurs known as birds account for about 10,000 living species. The biological characteristics of archosaurs must help to explain their success, but many aspects of archosaurian biology can be studied directly only in living birds and crocodilians. For extinct archosaurs, they must be inferred using fossil evidence, comparisons to living animals, and approaches such as biomechanical modelling.