According to the unscientific claims of the theory of evolution, reptiles are the ancestors both of birds and of mammals. When mammals are considered, it can easily be seen how impossible such a claim is. For example, let's think about tigers, cows, bears, elephants, dolphins, whales, mice and bats. There are great structural differences between these mammal species. Furthermore, each of these living things possesses systems specifically designed for their own needs. For example, dolphins have a very sensitive sonar system. Bears have mechanisms which are appropriate to the climatic conditions of their habitat.
Evolutionist zoologist R. Eric Lombard expresses what great difficulty these differences cause to evolutionists as follows:
Those searching for specific information useful in constructing phylogenies [evolutionary development] of mammalian taxa will be disappointed. (R. Eric Lombard, "Review of Evolutionary Principles of the Mammalian Middle Ear, Gerald Fleischer," Evolution, vol. 33, December 1979, p. 1230)
Apart from these differences, the fossil record demonstrates that mammals, like all living things, appeared on earth suddenly and fully formed with their present perfect structures, without any evolutionary process.