Feb. 24, 2006 A team of international researchers have
discovered a new species of primitive mammal capable of swimming
in the Middle Jurassic lake beds of China. In a cover article
published in Science, the team of researchers from Carnegie
Museum of Natural History, Nanjing University, and Chinese
Academy of Geological Sciences describe a fossilized skeleton of
Castorocauda lutrasimilis ([Castoro] - Latin for beaver, [cauda]
- Latin for tail, [lutra] -Latin river otter] and [similis] -
Latin for similarity). Castorocauda had a beaver-like tail,
strong arms for digging, and sharp teeth specialized for aquatic
feeding, similar to the modern river otter. Castorocauda is a
new taxon of docodonts, an extinct mammal group that existed
from the Middle Jurassic to Late Cretaceous. But this Mesozoic
group has no modern descendants, and is not directly related to
modern placental mammals. Uncovered from the Middle Jurassic
Jiulongshan Formation of the Inner Mongolia Region, dated
approximately 164 million years ago,