The diagram depicts information about development of horses including distinct accent on their feet changing during forty million years.In general,over the years horses had transpormed four times becoming stronger and taller year for year.These transformations also apply on their feet, toes combined into one whole.
The prehistoric horses which lived 40 million years ago called Eohippuses were radically different from nowaday horses.They did not had any hair despite tail and was short height without muscles.Their feet were like a chiken toe with four digits.The next stage of evolution was after another ten years, horses became bigger and more muscular.They were more understandable in head thone, their ears turned into sharper ones.Regarding to their feet,middle toes merged into big one.
The penultimate stage,almost same horses of now named Merychippuses already had mane and longer tail, phalanges grew length.The last step of evolution is the modern horse which drows into the tallest one.They have enough mane and a thick tail.In this stage they have not got toes,it turned to one sturdy hoof.