Unit 4 DB Organ systems and Evolution

EVOLUTION AND NATURAL SELECTION

Evolution of the Horse (Hyracotherium ) Specie

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Evolution of the Horse (Hyracotherium ) Specie

The individual specie of a horse known as Hyracotherium was believed to be the origin of the modern horses today known as Equus . The fossil lineage of primitive horses provided an evidence of directional succession in evolution . Evolution took placed as seen in the changes and development in the teeth , leg length and toe structure

The Hyracotherium was first found in Europe . It was then named Eohippus

. It had lived 55 million years ago . It was found during the Early Eocene era . During that time this kind of animal was common and found in other parts of the world . The fossil of this horse was collected and studied by scientist and found similarities with other early horses . It was replaced by Orohippus specie known as small horse ' and much bigger than the hyracotherium . This appeared 2 million years after it . Hyracotherium was described to be the size of a dog . It had a primitive face , with eye sockets in the middle and a short diastema or the space between the front teeth and the cheek teeth . It has low crowned teeth but with the characteristic of horse like ridges in the molars . Horses was believed to come from this small type of dog like animal which according to the theory of evolution and natural selection undergone extinction while its later generation evolved and improved to the modern horses we have seen today

The emergence of the Parahippus specie became somewhat the evolutionary link between the oldest hyracotherium horses to the modern horses . From a small body , shorter face , three toes and small teeth these species evolved into taller and larger bodies with longer face and one toed feature . Millions of years had passed and about 15 generations occurred before the modern horses came into the picture . They improved in their characteristics as more and more horses were domesticated and used as a means of transportation . From living in woodlands it moved to living in the highlands . Its legs were developed to help them from predators making them survive more in the environment therefore preserving the specie

Reference

Evolution and Natural Selection . Evolution and Natural Selection Retrieved

September 09 , 2008 , from HYPERLINK "http /www .sprl .umich .edu http /www .sprl .umich .edu

Horse Evolution . Talk Origins .Org . Retrieved September 09 , 2008 from http /www .talkorigins .org /faqs /horses .html

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