Fossil evidence for the origin of aquatic locomotion in archaeocete whales. Thewissen et al. Perhaps Ambulocetus should be classified with the archaeocetes, perhaps not. And Basilosaurus , younger by 10 My. Specimen with complete hindlegs now shows the increased adaptation to a seemingly fully aquatic lifestyle.
Legs are too small to support body weight on land.
Shimamura et al. Our analysis of SINE retrotranspositions seem to provide unambiguous support for that hypothesis. Artiodactyls are paraphyletic, the even-toed ungulates give rise to whales. This sort of controversy, here between the molecular biologists and paleontologists, adds spice to the study of vertebrate evolution. Surely there will be better understanding in time.