Named By: Q. Ji, Z.-X. Luo, C.-X. Yuan & A. R. Tabrum - 2006.
Classification: Chordata, Synapsida, Therapsida, Cynodontia, Mammaliaformes, Docodonta, Docodontidae.
Species: C. lutrasimilis (type).
Size: At least 42.5 centiemetres long for the holotype.
Known locations: China, Lianoning Province - Tiaojishan Formation.
Time period: Callovian of the Jurassic.
Fossil representation: Almost complete individual.
lack of a better description, Castorocauda was
basically like an
otter or beaver that lived during the Jurassic. However, while
Castorocauda superficially looks like them, the
genus is in no way a
direct relation to them, Instead, Castorocauda
is what is known as
a docodont mammaliform, and a member of a group that has no surviving
descendents today. Nevertheless, the genus and type species name of
Castorocauda lutrasimilis does translate as
‘beaver tail similar to
The adaptations made by Castorocauda to a semi-aquatic lifestyle are interpreted as being a case of convergent evolution, the process where two unrelated animals evolve the same adaptations to deal with the same survival situation. Castorocauda would have spent time hunting within the water, perhaps looking for fish and/or crustaceans while returning to land to rest and raise young. While on land Castorocauda would have been more vulnerable to predators especially smaller theropod dinosaurs. Modern otters usually shelter in burrows however, and this raises the question, if Castorocauda developed similar a body form to otters, then did Castorocauda also develop similar behaviour too?
- A swimming mammaliaform from the middle Jurassic and ecomorphological diversification of early mammals. - Science 311:1123-1127. - Q. Ji, Z.-X. Luo, C.-X. Yuan & A. R. Tabrum - 2006.