Evolution of the horse Flashcards
What does the extensive fossil record of the horse reveal?
The evolution of the horse has a branching nature. Several different migrations, changes in size and populations. Shows gradual microevolution.
What have been the main evolutionary changes that have occurred in the horse?
Body size, number of toes, grinding surfaces on teeth
From which epoch did the first horse originate?
The Eocene epoch
Describe the first horse.
Resembled a dog, only 25-50cm tall. Long tail, short legs and snout, ate fruit and soft plants. Teeth were low crowned with ridges. Lived in dense forests. 5 toes.
Describe the horses of the Oligogene epoch.
Evolving from the first horse, the horses of the oligogene developed teeth with more grinding surfaces, so eat tougher plant material as the climate got drier. Also was increased in size, and had one less toe, responding to how forests shrank and grasses began to flourish.
Describe the horses of the miocene epoch.
These horses had a gradual increase in the height of teeth crowns, they grew larger and longer, became better at running. Face was longer, bones fused in legs so they could stand on their 3 toes, better for running.
Describe the horses of the pliocene epoch.
Lost their side toes, development of fetlock (joint with lots of support ligaments, good for running, reduced toes). Central toe was stabilised for running. Continued to be larger.
