Early Mammal Evolution
The prevailing view of mammalian evolution is that with the extinction of the dinosaurs, the doors were opened for mammals to greatly diversify and fill a number of ecological niches. While this trend may hold true, new findings will likely reshape our thinking on some of the details. For example, recent finds of predatory mammals from the Cretaceous (just before dinosaurs went extinct) of small predatory mammals (one even has a dinosaur remains in it’s stomach) give evidence that mammals were diversifying before the extinction of the dinosaurs.
Castorocauda lutrasimilis
A new find from the Jurassic (which preceeds the Cretaceous) tells of an early aquatic mammal that was probably most similar to our modern platypus.
This mammal had a beaver-like tail, with webbed feet and seal like teeth, and it offers further evidence that mammals were diversifying earlier than we thought. It also provides the earliest evidence for fur in mammals.
This is what I find so exciting about evolution and biology. There’s always more to learn, and new evidence comes to light to challenge our understanding.
You can bet that two things will happen because of this new find. Young earth creationists will point to it as proof that the fossil record doesn’t show evolution, while intelligent design advocates will use the flawed logic of “if biologists can’t even get the evolution of beaver-like mammals right, how do we know they’re right about anything…” Both are regrettable and dishonest.
When Einstien realized there were problems with our theories of gravity, he worked to provide new understandings. He didn’t suggest the apple doesn’t fall from the tree. In the same way, Jurassic beaver like mammals don’t overthrow our theory of evolution, rather they overthrow our theory that mammals remained small and “undiverse” until the extinction of the dinosaurs. And while we evolutionary biologists can be a persnickety group, we also build our theories on the evidence around us. Sometimes that evidence causes us to change our understanding. This is a good and healthy thing, not to mention the very essence of science.