Erickson Gregory M, Curry Rogers Kristina, Varricchio David J, Norell Mark A, Xu Xing
Department of Biological Science, Florida State University, Tallahassee, FL 32306-1100, USA.
Biol Lett. 2007 Oct 22;3(5):558-61. doi: 10.1098/rsbl.2007.0254.
The timing of sexual maturation in non-avian dinosaurs is not known. In extant squamates and crocodilians it occurs in conjunction with the initial slowing of growth rates as adult size is approached. In birds (living dinosaurs) on the other hand, reproductive activity begins well after somatic maturity. Here we used growth line counts and spacing in all of the known brooding non-avian dinosaurs to determine the stages of development when they perished. It was revealed that sexual maturation occurred well before full adult size was reached-the primitive reptilian condition. In this sense, the life history and physiology of non-avian dinosaurs was not like that of modern birds. Palaeobiological ramifications of these findings include the potential to deduce reproductive lifespan, fecundity and reproductive population sizes in non-avian dinosaurs, as well as aid in the identification of secondary sexual characteristics.
非鸟类恐龙性成熟的时间尚不清楚。在现存的有鳞目动物和鳄目动物中,性成熟与成年体型接近时生长速率开始放缓同时发生。另一方面,在鸟类(现存恐龙)中,生殖活动在身体成熟后很久才开始。在这里,我们利用所有已知的孵卵非鸟类恐龙的生长线数量和间距来确定它们死亡时的发育阶段。结果表明,性成熟在达到完全成年体型之前就已发生——这是原始爬行动物的情况。从这个意义上说,非鸟类恐龙的生活史和生理机能与现代鸟类不同。这些发现的古生物学意义包括有潜力推断非鸟类恐龙的繁殖寿命、繁殖力和繁殖种群规模,以及有助于识别第二性征。