First of all read the posts and look at the pictures. That's what they show. I may be getting mixed up on who said what exactly but the thought is the same.
Actually I was responding to a specific assertion that was made here, that there were no creatures that can be shown to be the ancestor of two species. I presented pictures that illustrate one creature, the Hyracotherium, to be indeed an ancestor (or close cousin of an ancestor) of several species.
This one fact does not prove common descent of all animals. It confirms the point I was making.
The explanation is these fossils are not evidence since they cannot be shown to be actually evolving. They are scattered throughout the planet and suddenly appearing as complete creatures. It is assumed they evolved from one to another.
Actually, no, the fossils leading to the horse are not scattered about the world. All of the evolution from Hyra to Equus is documented by fossils in North America (see
Horse Evolution Over 55 Million Years ).
And the point is that we are not dealing with sudden appearance of new creatures. Rather, there is a long line of creatures that step by step look more like the modern horse, donkey and zebra as time goes on. Knowing this, it is very difficult to escape the conclusion the Hyrocatherium evolved into zebras.
This is still not evidence that all life came from a common ancestor even if the horse thing was accurate. And that's a mighty big if.
How do you explain the available evidence? Nothing close to a horse or zebra is found 50 million years ago. Instead we find an abundance of Hyracotherium. Then we gradually see an introduction of creatures that look more and more like a horse and zebra as time goes on. Do you agree that the most likely explanation is that Hyra evolved? If not, how do you explain those fossils down there?
If you can address the question of horse evolution, we can ask what you think of other evolution. But if you cannot address this case that has such strong evidence, there is not much need to push the debate further. See
Horse Evolution .