The diagram depicts how the horse’s body has changed over years, with special emphasis on the formation of the feet.
Overall, it is readily apparent that as horses became larger in size, the structure of their feet and legs also increased in size, the legs elongated and broadened until they fused to become a distinctive hoof.
B1: The prehistoric horse from 40 million years ago, known as Eohippus, is specified by its smaller body and paw containing 4 thing phalanges. The next stage of evolution is Mesohippus, which is bigger than it is ancestor (Eohippus) and has a longer fused foot.
B2. By 15 million years ago, the Merychippus had emerged, undoubtedly, it is pictured as a bigger body and an increased size of the middle digit. This leads directly to the modern day horse, which has much larger size than all it is ancestors, has a full mane, longer tail, and and the separate digits had by this time merged into a single hoof, which is capable heavy body of the modern horse.
