Dr. Brooke Armfield at the University of Florida, and Dr. J.G.M. 'Hans' Thewissen, Professor of Anatomy at Northeast Ohio Medical University, reported the most sophisticated genetic and paleontological examination of how whale teeth developed in the open access journal PeerJ on Feb. 19, 2013.
Not all whales have teeth. The whales that have teeth have only one kind of tooth unlike the majority of mammals that have as many as four kinds of teeth. Toothed whales have rows of simple peg like teeth.
The fossil record indicates whales originated on land and 48 million years ago whales had the same four kinds of teeth just like most other mammals. Over time whales that have teeth lost all but one kind of tooth around 30 million years ago. This adaptation occurred before whales evolved the majority of familiar water living adaptations that present day whales have.
The scientists found that two proteins, BMP4 (Bone Morphogenetic Protein 4) and FGF8 (Fibroblast Growth Factor 8) control whale tooth development. A comparison of whale teeth with dolphins and other mammals determined that theses two proteins are responsible for the position and shape of teeth in mammals.
The changes in location of the two proteins determine the tooth strucutre in all mammals.