Modern horses (family Equidae) are represented by just one large-bodied and single-toed genus, yet their earliest ancestors were dog-sized animals with three or four toes on each foot. Reducing the number of toes, or digit reduction, can be found in lineages as distantly related as theropod dinosaurs and hopping desert rodents. But why? Through their evolutionary history, different species of horses can be found far-flung in geography, living in habitats from open grassland to forested hills, increasing or decreasing in body size, grazing or browsing, reducing digits or not reducing...
Read more about Exploring digit reduction in fossil horses