For a long time, mammals that coexisted with dinosaurs were imagined as tiny mouse-like creatures, busy foraging under the canopies of bushes. However, a recent discovery of a marine creature with fur, seal-like teeth, and a beaver-like flat tail has overturned this image.
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Castorocauda lutrasimilis is the largest known mammal from the Jurassic period. It lived about 165 million years ago, during the middle Jurassic, and is not a direct relative of modern beavers. (AP) |
Approximately 164 million years ago, this newly discovered creature swam in the lakes of what is now northern China, catching fish and sharing its habitat with dinosaurs.
“Its lifestyle might have been very similar to that of modern platypus otters,” stated Zhe-Xi Luo, a vertebrate paleontologist at the Carnegie Museum of Natural History in Pittsburgh. “It likely lived along rivers or lake shores, paddling its feet, eating insects and organisms in the water, as well as digging burrows for nesting.”
Luo’s research team from the Chinese Academy of Geological Sciences in Beijing discovered fossil fragments of this creature in Inner Mongolia.
Thomas Martin from the Senckenberg Research Institute in Frankfurt, Germany, noted that this discovery pushes back the timeline for aquatic mammals by more than 100 million years, as modern semi-aquatic mammals like otters, beavers, and marine mammals like whales did not appear until 55 to 25 million years ago.
Importantly, the recently found creature shows significant specialization. “It provides evidence that primitive mammals were not merely shadows during the age of dinosaurs, but capable of evolving on their own,” commented Matthew Carrano, a dinosaur curator at the Smithsonian National Museum of Natural History.
This is also the first evidence indicating that some ancient mammals were semi-aquatic animals, demonstrating that the biodiversity of that era was much greater than previously thought.
The newly discovered animal is not directly related to modern beavers or otters, yet it shares many characteristics with them. Consequently, scientists named it Castorocauda lutrasimilis. “Castor” is Latin for beaver, “cauda” means tail, “lutra” refers to river otter, and “similis” means similar.
Weighing between 500 to 750 grams, and roughly the size of a small platypus, Castorocauda is also the largest known mammal from the Jurassic period.
T. An
