Evolution of the Horse

The evolution of the horse can be traced through the fossil record up to Hyracotherium, a small herbivore that lived during the Eocene, 55 million years ago in North America. It is supposed to descend all subsequent equines, including genus Equus.

Features horseThere are three characters that best illustrate the trend in the evolution of the horse , these body size, the structure of the legs and the structure of the teeth.The modern horse belongs to the order Perissodactyla , the odd hoofed ungulates gifted ( one to three ) Seven major adaptations are obvious in modern horses. :1. - The elongation of the eye anterior skull which is a consequence of their eating habits. A long head allows you to reach the ground without much lengthening the neck.. 2 - The diastema , or space between the incisors and the premolars and molars battery . This space is the man who used to put the bite with handling the animal.. 3 - Very long teeth hipsidonte type , which continue to grow throughout the life of the animal and that in adaptation to food grinding lines are provided on a matrix of enamel dentin.. 4 - The provision of all digits except the third and the rudiments of the metacarpals and metatarsals of the second and third digit are like stilettos on top.. 6 - Modification of the third metacarpal and metatarsal digit becomes a thick, powerful bone cane .. 7 - The strong ligament that originates in the back of the rod and extends to the sesamoid bones forming a pulley in the region of the fetlock . Other sesamoid ligaments connect with the phalanges of the hoof , all forming a spring mechanism that keeps the hoof between voltage ( bending ) when the tent on the ground and propel the animal forward.Adaptive radiation that gave rise to modern horse just described , then, included the following changes ; a) the elongation of the skull from conventional short and elongated size to the present; b ) the occurrence of the diastema , c ) the elongation of the teeth and the development of the pattern of enamel and dentin in the world the modern horse ; d ) the increased size and greater complexity of the brain ; e) the amendment of a leg with three fingers in digitigrade animals , a single finger and unguligrado ; f ) the evolution of the cane and the fetlock .If you look at the Eocene , we will see many different genera and species of horses which ran in time compared to the first modern horses were small , her teeth had a relatively small surface abrasion and legs had a higher number of fingers (four ) . Throughout the following periods Oligocene , Miocene , Pliocene and Pleistocene , as is seen new genres and old are becoming extinct . In all cases a clear increase of the body size increased abrasion surface teeth and reducing the number of fingers is produced in accordance latter reduced the central finger is made ​​larger , prevailing today.Hyracotherium : Eohippus known as , the size of a "fox terrier" short legs, with four toes in front and three behind, although the third finger is bigger and the first rear leg is quite small ; unsprung leg ligaments , but possibly also supported by bearings and a tendon that originates at and extends muscle fetlock ; region of the skull above the orbits not long : molars and different , not elongated and like the wheels of human besides her teeth were adapted for the consumption of young leaves of the bushes and your eyes tubers premolars were also different , as they were located closer to the center of the head preventing a good lateral view ; small and smooth hemispheres ; he lived in the jungles of North American and European Eocene . His fingers spread and the bearing that held seem to have been an adaptation to move the soft , moist jungle environment in which dwelt floor. Apparently , the animal is protected and unlikely hiding your skin has been spotted for camouflage was more effective to avoid predators .Mesohippus : the size of a sheep ; three toes on the front paws or one on the back ; the more elongated fingers that Hyracotherium bearing persistent ; preorbital skull begins to lengthen and the diastema appears ; almost all the same to the molars premolars , teeth had low crowns ; larger and convoluted cerebral hemispheres that Hyracotherium . Inhabitants of the forested regions will Oligocene in North America.Parahippus and Meriychppus : about the size of a pony ; keep three fingers on each paw, but the third finger is quite dominant and sides may not touch the ground ; the skull is quite elongated ; the diastema is higher than in previous species , there is no difference between his molars molars and premolars are more elongated and have some Hyracotherium dentin Meriychippus all these characters reached greater and there was already an elastic ligament in the fetlock . His teeth were clearly hipsinodontes their molar crowns were high and his jaw was profound. The animal was grazing in the meadows possibly although it is possible that the bearing has not disappeared . His brain was like a slightly smaller but modern horse . Parahippus was an inhabitant of the Miocene of North America, their offspring lived Meriychippus high Miocene of the same region.Pliohippus and Equus : The number of fingers is reduced to one, although the side Pliohippus had rudimentary fingers . The side formed a pair of primitive sobrehuesos placed along metatarsal and not seen externally . The head is extended still further, the size of the body increases , the wheels continue to elongate and become more complex . The transition from Equus Pliohippus to mean only increasing in size and some minor anatomical changes. Pliohippus appears in the Pliocene of North America where then dies , but not before invading Europe , Asia and Africa. In the old world still prevail nine species ( horse four zebras and four asses) . The modern horse Equus or appears at the end of the Pliocene , and extends to the Old World, via Alaska and Siberia.As we have seen one of the essential elements in the progress of the horses was the changing food habits. There were two types of ramoneadotes , inhabiting the forest and like deer feeding on leaves and twigs of shrubs ; and grazers , grazing in the meadows and ate the most hard and abrasive grasses . E adaptation to these habits , teeth of grazers were higher and more resistant to abrasion, longer neck and head (to reach the floor) , the muscles of mastication different , and the legs were longer and had changed considerably in these animals, whose defense consisted mainly of running away . In the late Oligocene and early Miocene , the grazers seem to have dominated and late Tertiary , all ramoneadotas species were extinct .With this knowledge we can extend the look back , review the crow flies , the ancestors of modern horses and see how these adaptations were acquired during course of geologic time. It should be understood , however, that this process did not occur in a straight line where there were several irregularities and deviations culminating lines then died .