Equus Skulls Evolution

evolutionary trend that causes this increase because for many species, having a bigger body size results in an increase in fitness. However, there are several changes that occurred in the Equidae family that are as significant to evolution as body size.

The discovery of Equidae fossils worldwide has provided excellent evidence of the evolution which has affected many characteristics of the family. An example of one or the most notable alternations seen between the first ancestor, the Eohippus of the Eocene period, and modern Equus can been seen in the feet and limbs of each and through the many related species also in the family tree. As previously mentioned, the Eohippus was a small creature with short, but sturdy limbs with four toes …show more content…
Another example of change over time in this specific family is observed in the skulls of its members. The oldest skull found that has been classified as an Equus skull was discovered in Southern California. Before this specimen was found, many scientists could not be certain of how far in history the Equus caballus appeared or if any significant changes had evolved. When compared to Equus skull structures, the skull structures of the Eohippus appear entirely unrelated. Both skulls are consist of a cranium, the space where the brain is located and protected, a muzzle, the face and nose of the Equidae, and the mouth and jaws. When observing the Eohippus skull, the eyes are located at a nearly equal distance between the end of the cranium and the end of the muzzle and the mouth had very few gaps between teeth. However, as evolution progressed to the Mesohippus, the distance between the eyes and the end of the muzzle had increased and as a result, larger gaps were observed between the front and back sets of teeth. The nasal bone between the two nostrils became thinner and no longer reached the muzzle. The length of the muzzle continued to increase from the Meryohippus to the Equus. Many scientists have proposed explanations for these changes based on gathered evidence. The most commonly accepted hypothesis states that due to the shape and position of the head …show more content…
Teeth can be used to identify the age and gender by the number and size present. On average, male horses possess forty teeth when fully mature while females possess thirty-six. The most highly studied characteristic of any member of the Equidae family are the sets of teeth and the different types of teeth: the incisors, the cheek teeth (the molars and premolars), and in some cases, the canines or wolf teeth. Many people have proposed that the evolution of equine’s teeth and mouths was due to a change in diet from browsing to grazing as forests were gradually replaced by grasslands. Although most evidence has supported that proposal, it is important to note that other factors would also have played a part. Scientists who have studied the teeth of the Eohippus have agreed that its most likely diet was small seeds and fruits based on its small premolars and low crowned molars. The molars were small and triangular in shape, but were used to chew the soft food before it was digested. However as the descendants of the Eohippus moved into the Oligocene, the molars and premolars on the upper and lower jaws showed increases in size and the premolars slowly began to resemble molars. The most remarkable change took place during the Miocene when the teeth experienced rapid modification in tooth height, pattern, and protection. Around this era, the spacing and fusing of the teeth changed to