Horses have interesting anatomy especially their hooves. This article does not mention horse feathers, but those are nothing like Pegasus.
Modern horses evolved to have a single, weight-bearing toe enclosed in a hoof, but their ancestors had multiple toes, and vestigial remains of those side toes can still be found on their bones. [1, 2, 3, 4, 5, 6]
Here’s a more detailed explanation: [4, 7]
Evolution of the Single Toe:
Early equids (the ancestors of horses) had multiple toes, with four on the front feet and three on the hind feet. Over millions of years, the side toes gradually reduced in size and eventually disappeared, leaving only the middle toe, which became the sole weight-bearing digit. [1, 3, 4, 5, 7]
Vestigial Toes:
While the side toes are gone, the bones that once supported them remain as small splint bones, located above the hoof. [2, 3, 6]
Why a Single Toe?
The evolution of a single toe likely helped horses become faster and more efficient runners, as having one large, robust toe was more advantageous for their large size and speed. [5, 6]
Other Animals with Single Toes:
Horses, donkeys, and zebras are all odd-toed ungulates, meaning they walk on a single toe per foot. [8]
The Frog:
The triangular frog on the sole of the horse’s foot is a unique structure that evolved independently of the side toes and provides shock absorption and traction. [9, 10, 11]
Generative AI is experimental.
[1] https://www.theguardian.com/science/2017/aug/23/how-the-horse-became-the-only-living-animal-with-a-single-toe[2] https://www.science.org/content/article/why-modern-horses-have-only-one-toe[3] https://www.amnh.org/exhibitions/horse/the-evolution-of-horses/on-your-toes[4] https://academic.oup.com/icb/article/59/3/638/5498567[5] https://www.nytimes.com/2017/08/28/science/horses-hooves-evolution.html[6] https://thehorse.com/194132/how-the-horses-hoof-functions/[7] https://www.smithsonianmag.com/smart-news/study-shows-how-horses-ended-only-one-toe-180964618/[8] https://www.ifaw.org/journal/amazing-animals-with-hooves[9] https://pmc.ncbi.nlm.nih.gov/articles/PMC10282582/[10] https://www.earth.com/news/experts-confirm-that-modern-horses-lost-their-additional-toes/[11] Where did those 'extra' toes go? - Equus Magazine