The diagram illustrates the evolutionary trajectory of the horse, with particular emphasis on the significant modifications in its foot structure. From an overall perspective, it is evident that this species underwent significant evolutionary changes, resulting in a larger body size and the development of a single, elongated hoof in place of its ancestral digits.
The available evidence suggests that the Eohippus, an early ancestor of the modern horse, originated approximately 40 million years ago and was characterised by a distinctive paw structure comprising four separate toes. Approximately 30 million years ago, the horse’s evolutionary progression reached the Mesohippus stage, characterised by an increase in body size and the development of three distinct toes.
The Merychippus species emerged approximately 15 million years ago and exhibited a greater degree of similarity to the modern horse, displaying a more substantial increase in bulk and a slight elongation in comparison to its predecessors. This direct line of evolution has culminated in the modern horse, which is distinguished by its larger size, a flowing mane and a single hoof resulting from the merging of ancestral digits.