WHERE IT ALL STARTED.
This page gives only a general overview of the evoulution of the Shetland Pony and is far from complete. Sources of more detailed works will be given in due course.
Hyracotherium ( The Dawn Horse ) & Eohippus
The very earliest ancestor of the horse lived in the Eocene Epoch between 33.9 and 55.8 million years ago. It was 30 to 60 cms high, in some of the species the face was long and with more of a snout than muzzle. It also had a long tail. The legs were slender with the hind legs longer than the forelegs so it was well adapted for running, there were four hooved toes on the front legs and three hoofed toes on the hind legs. The size and shape of their teeth indicates that they were browsers that fed on leaves and possible berries rather than grass. Many complete fossils have been found in North America (Eohippus) and Europe (Hyracotherium) although the populations in Europe seem to have died out.. Eohippus developed into :-
Around 50 million years ago Orohippus had developed. The main difference between Hyracotherlium & Eohippus, and Orohippus was the shape of their teeth, which were now adapted to a more specialized diet of a certain type of leaf. Although they were around the same size the body and legs were slimmer, the head slightly elongated.
Epihippus evolved about 47 million years ago, and the trend of increasingly efficient grinding teeth was continued. Epihippus was around 60 cms tall.
Between 38 and 24 million years ago North America became drier, the forests began to give way to flatlands where the earliest grasses began to evolve. This was in response to relativly sudden climate change. Mesohippus evolved in response to the changing environment, becoming slightly larger with longer legs, this allowed for faster running speeds in the open areas in order to evade predators. Also six grinding teeth (one more than Epihippus ) were developed for grinding down tough vegetation. Mesohippus became one of the most widespread animals in North America. Mesohippus neck and face were slightly longer and began to show signs of a muzzle, walked on three hooved toes of each foot, the other toes were no longer used for walking having diminised use.
There is evindence to suggest Miohippus co-exsisted with Mesohippus for around 4 millon years, after part of the population of the former split with the later and evolved seperately. Then gradually Mesohippus was replaced with Miohippus who contiued to thrive, branching out into two major groups, one group adjusted to life in the wooded areas, the other remained suited to the open areas.
Kalobatippus & Anchitherium
The forest suited group of Miohippus were Kalobatippus who in turn gave rise to Anchitherium which spread from North America to Asia then Europe where they developed larger bodies. From Anchitherium, Sinohippus evolved in Asia and Europe, and Hypochippus and Megahippus in North America, although Hypohippus became extict around 5 million years ago.
The Miohippus group that remained in the more open areas of North America, it is believed evolved into Parahippus, who was about the size of a small pony. Parahippus had a prolonged skull and the structure of the face resembled the face of todays horse.
Merychippus & Hipparion
Merychippus was a grazer who had developed wider molars for eating hard grasses in the open prairie like areas of North America, around 26 millon years ago. Among three lineages believed to have descended from Merychippus, Hipparion was the most different. They were the size of small ponies but slim and having three hooved toes on each foot although the side toes did not touch the ground. The middle toes had become larger in oreder to take the weight of the rebalaced body, enabling faster running speeds in order to out run pedators in the open areas. Many species of Hipparion flourished and at least one or more migrated to Asia and Europe. American Hipparion was larger in body than the Asian/European Hipparion.
Pliohippus had evolved by around 12 million years ago. Pliohippus was regarded to be the last stage of evolution from Eohippus to the true horse. The single toe had developed into the strong hoof, although the smaller toes were still visible as stubs, the teeth have developed becoming larger with higher crowns, (although slightly curved) making them even more efficient grazers.
Equus includes all extant equines, it is believed to have evolved from Dinohippus via Plesippus. Dinohippus was at one time the most common species of Equidae in North America. Plesippus migrated to Asia/Europe from North America about 2.5 million years ago, where they diverged into many different types as they adapted into varying habitats. Although larger in body, and their grinding teeth had become straight making them superbly adapted to grazing, they looked little different to Phiohippus. Most experts seem to agree that three distict lines emerged from a common Equus ancestor, the Horse, the Zebra and the Asses.
Different tpyes of horse then adapted to suit the various conditions in which they lived one of these types was the type which had adapted to life in areas of hills and mountains, and another the Tundra type known to have adapted to life along latitudes 45 t0 50 degrees.
Maurice C Cox in his book The Shetland Pony. States that in light of present knowledge (1965) the Shetland Pony has it’s origin in two types of horses. The 13.2 hands Cob type Tundra, and the 12.2 Mountain Pony type. This was then crossed centuries later by the Celtic people with the Oriental horse. and after a few more centuries the horses introduced be the Vikings.
( to be continued ).
Reccommended Reading :-
The Shetland Pony by Maurice C Cox, Published by Adam & Charles Black
Survival of the Fittest, A Natural History By Sue Baker, Published by Exmoor Books
The Shetland Pony by Charles & Anne Douglas, Published byWilliam Blackwood & Sons