The walking whale that swims… well, swam.
I’m actually going to start something new on this blog, for a change. How exciting, right?! Akay, so here’s the deal. Every Tuesday from now on is going to be Transitional Fossil of the Week day! THAT IS SO COOLEY.
(Well, it might be Monday if you live in the States, but it’s definitely Tuesday here.)
And today’s transitional fossil is… is…
Haha, I’m just joking. Today’s transitional fossil is… is…
Ambulocetus natans - The scientific name “Ambulocetus” means walking whale, and “natans” means that swims. So basically, it’s a walking whale that swims… well, swam (Ambulocetus natanned?). This 3-metre-long creature looked somewhat like a crocodu… dile, and lived in the Early Eocene period some 49-50 million years ago. Fossils of the Ambulocetus natans were found in Pakistan.
The Ambulocetus was an amphibian, and its hindlimbs were clearly adapted for swimming. Its ear-bones and teeth were very much alike that of modern whales, and it could swallow underwater. The Ambulocetus postdates the famous Pakicetus, an Eocenic land mammal (whose fossils were also found in Pakistan), and predates other cetaceans to come.
Well, here’s Ambulocetus with reference to the cetacean phylogeny. Notice how the diagram to the right doesn’t actually show a single lineage of whale evolution (ie. Pakicetus and into Ambulocetus and into Dalanistes, etc.). Instead, the diagram is actually an evolutionary tree showing common ancestry (at the nodes).