It happens all the time with habitat change. The Early Eocene in Utah and Wyoming was a much wetter and forested habitat. Hence lots of trees, water and variety. The dominant tree-dwelling Perissodactyls (later horses and such) and the Primates ere all tree-dwelling mammals until the climate changed and vast grasslands filled the area. Early tree-dwelling Perissodactylans strongly resemble one another in limb and toes and manus).

Patrice Showers Corneli I had to look up your term, "tree-dwelling Perissodactyls" since I knew of only terrestrial perissodactyls. I came up with one: tree-dwelling hyrax. Can you name a few "tree-dwelling Perissodactyls" by genus? Perhaps list only those known from more or less complete skeletons. No dental taxa, please.