Paraphrase paragraph: diagram>pictures; show>illustrate; development>evolution
Overview/summary paragraph: 4 stages, mention the first and last stage
Paragraph 3: report on the differences between Eohippus and Mesohippus
Paragraph 4: report on the differences after Mesohippus up to the modern horse
The pictures illustrate the evolution of the horse over a 40 million-year period.
Overall, four stages are shown, beginning with Eohippus and ending with the development of the modern horse.
40 million years ago, the first horse, Eohippus, was comparatively small with a short tail. Its defining characteristic, however, was the structure of its foot, which had 4 digits. Each of the digits was relatively small. 10 million years later, it had evolved into the larger Mesohippus, with a longer tail and a foot structure of 3 digits.
Then, in the next stage of development, Merychippus evolved 15 million years ago. It was a similar size to Mesohippus, and also had 3 digits on its feet, but now the digits on the feet were larger, divided into segments, and the middle digit was very prominent.
Finally, the modern horse evolved. It is bigger than its predecessors, with a large mane and its foot structure is a single, very large digit.