Question

What is the main characteristic that separates hominids from other animals?

Answer 1

In the fossil record it is difficult to distinguish between the fossils of what is considered to be hominids, and what are considered to be apes.

Explanation:

The size of the brain cavity is one factor, but Lucy had a very small brain cavity and is considered to be a hominid.

The ability to stand on two legs is another factor that is used to distinguish between hominids and the great apes. This is also suspect as the Java man thought to be an early hominid turned out to be a great ape.

The ability to use tools is a factor in determining the status of fossil.
The location of shaped rocks near the bones of Lucy was one factor that was used to make the determination that Lucy as a hominid.