Temporal range: Upper Jurassic
Ji et al., 2006
Castorocauda is a genus of small, semi-aquatic relative of mammals which lived in the Jurassic period, around 154 million years ago. It was found in lakebed sediments of the Daohugou Beds of Inner Mongolia. Castorocauda] was highly specialized, with adaptations like those of modern semi-aquatic mammals such as beavers, otters, and the platypus (convergent evolution). It also had traces of fur.
- Ji, Q.; Luo Z-X, Yuan C-X, and Tabrum A.R. (2006). "A swimming Mammaliaform from the Middle Jurassic and ecomorphological diversification of early mammals". Science 311 (5764): 1123. doi:10.1126/science.1123026. PMID 16497926. http://www.sciencemag.org/cgi/content/abstract/311/5764/1123. See also the news item at "Jurassic "Beaver" found; rewrites history of mammals". http://news.nationalgeographic.com/news/2006/02/0223_060223_beaver.html.