Teeth are one of the most common vertebrate fossils found, partly because they preserve far better than any other body part. If any evidence exists for Neo-Darwinism, it would most likely be found in fossil teeth. The results of a literature research on the origin of teeth show no empirical support for their evolution. A review of the fossil record shows no evidence of transitional forms that bridge teeth to their theorized precursors, such as bone. Nor has any clear evidence been found to support the evolutionary origin of various types of teeth, such as molars or tusks. The complexity of teeth, and the complex inter-connections between teeth and bone, also conflict with a Neo-Darwinian origin of teeth.