Suppose researchers discover as fossil of an organisms that lived 300 million years ago but had mammalian teeth and amammalian jaw hinge. What inferences might you draw from this fossil about the origin of mammals and the evolution of novel skeletal structures? Explain.

Researchers may suppose that the fossil in question might represent an evolutionary link between mammals and reptiles. The mammal-like reptiles (therapsids) had distinctive morphological features such as teeth and jaws. However, the first mammals found date from around 178 million years ago, and thereby 300 million years seems too speculative