While in Tallahassee a half-century earlier he had seen some of the earliest fossils found at that site, but he had not visited it until our trip with him. The George Gaylord Simpson Paleontological Library has been a major addition to our research program and we will be forever grateful to him for his generous gift. Oxford University Press. An Unconventional Autobiography . Yale University Press.
Most mammals have a similar group of tissues making up their teeth.
In primitive mammals the enamel forms the principal chewing surface until old age, when in some mammals it is breached and the underlying dentine is exposed. There are many variations upon the basic theme seen in primitive mammal teeth. These lakes can vary from simple in forms like Pseudhipparion to very complex in modern Equus and some fossil forms like Cormohipparion . The reason why advanced horses evolve complex teeth is a classic story in paleontology that we will also elaborate upon in later issues of Pony Express . For now, the simple explanation that the high-crowned teeth, with complex enamel surfaces exposed throughout the life of an individual, are advantageous when feeding on abrasive foodstuffs like grasses.