The Open Door Web Site
The origins of life
Stephen J Gould (1991) Bully for Brontosaurus Penguin Books
Evolution of the Horse
Horses belong to the Perissodactyla, the odd-toed ungulates. This group includes horses, rhinos and tapirs today but it was a much more diverse group 50 million years ago.
The genus Equus includes horses, zebra and asses, are themselves the last remaining branch of a diverse group of equids. This is similar to the status of Homo sapiens being the last remaining species of a once diverse group of Hominids.
The evolution of the horse, however, is much better documented than ours. The fossil record is very complete.
In the evolution of the horses we can see a number of trends:
The trends correspond to changes in the climate and vegetation of the Earth over the past 55 million years, combined with an arms race between predators and prey.
FROM rich rainforest which covered most of the Earth in which the horses ancestors browsed on leaves and hid from predators.
TO open savannah grassland where the modern horses grazed grass and had to run from predators.
The view of evolution in Darwin's day was that of Gradualism. One species slowly transforming into another.
The modern fossil record reveals a different picture.
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