Protoavis are well preserved, and they are astonishingly non-avian. The distal carpals, while long, are in no way similar to those observed in the urvogel or other archaic birds. There is no semilunate element, and the structure of the radiale and ulnare would have limited the flexibility of the wrist joint. The manus is not tridactyl, and metacarpal V is present. In even the most basal avialian, "Archaeopteryx", there is no vestige of the fifth metacarpal and its presence in "Protoavis" seems incongruous with the claim that it is a bird, let alone one more derived than "Archaeopteryx". Chatterjee claims that
Dinosaur tooth data that has been collected through dinosaur dental histological studies are typically unavailable through other means and has provided us with a more in-depth understanding on their biology. One of the most significant findings is that despite differences in their appearance, dinosaur teeth are essentially composed of the same dental tissues found in modern mammals, crocodilians and other amniotes, suggesting that these tissues first evolved in a common ancestor and has been retained ever since. Another finding is that the lines of von Ebner can be counted similar to tree rings to determine the age of a tooth. Furthermore, as