The first exhaustive comparison of the anatomy of ankle bones in Earth’s earliest primates to other ancient primates and modern primates indicates the first of Earth’s primates lived in trees. Stephen Chester, assistant professor at Brooklyn College in the City University of New York, and colleagues have hopefully settled a century old running argument among anthropologists and biologists.
The ankle bones of a new specimen of Purgatorius found in Montana has provided the necessary evidence to conclude that the first primates lived in trees. The ankle bones are 65 million years old. No other fossils of Purgatorius had been found previously except teeth and jaws.
The ankle bones of Purgatorius allowed the animal to rotate all of its legs and grasp in all directions. The structure is very similar to modern monkeys that are known to only live in trees. While the small shrew-like Purgatorius may have ventured out on the ground occasionally, the animal lived most of its life in trees. The animal most probably ate fruit, nuts, and leaves.
The discovery will force most anthropology, biology, and paleontology texts to be rewritten. The assumption that the animal was a land-dweller based on teeth was valid at the time it was first expressed. The new evidence indicates that previous thinking was not correct. Science is evolving just like every other living thing. The study also indicates that the emergence of primates that were strictly land-dwelling was a slower process than previously thought.