Scientists say that flatworms are the oldest living ancestors of those of us that have right and left sides - that means you!

At the online companion Web site of "Evolution," the seven-episode series on PBS, piece together clues to how one of our early ancestors looked as you examine images from four significant fossil finds of Australopithecus afarensis.

Describes Homo habilis and Homo erectus, two early ancestors of humans. Discusses how they were discovered, their characteristics, and what we know about them, with the information clearly laid out in a chart along with some comparative...

Discusses the discovery of Homo neanderthalensis and describes the different theories that have been put forward to explain why Neanderthals became extinct.

Ammonoids, more commonly referred to as Ammonites, are the extinct ancestors of today's octopus, squid and nautilus. This page shows several types.