Hyopsodontidae

Hyopsodontidae is an extinct family of hoofed mammals that lived during the Paleocene and Eocene epochs. These small, primitive ungulates are considered to be among the earliest and most basal members of the Perissodactyla, the order that includes horses, rhinoceroses, and tapirs. Hyopsodontids were generally small, with most species no larger than a modern fox or badger. They possessed plantigrade or semi-plantigrade feet, meaning they walked on the soles of their feet, unlike modern ungulates which are digitigrade (walking on their toes). Their teeth were relatively simple, adapted for grinding plant material, suggesting a herbivorous or omnivorous diet.

The fossil record of hyopsodontids is found primarily in North America and Europe. Early members of the family, such as those from the genus *Hyopsodus*, exhibit traits that link them to earlier insectivorous or omnivorous mammals, suggesting a transition towards herbivory. Later hyopsodontids show a greater degree of specialization for herbivory. While their exact evolutionary relationships are still debated, hyopsodontids represent an important step in the diversification of hoofed mammals, demonstrating early adaptations that would eventually lead to the more specialized ungulates seen today. Their extinction is thought to be related to changing environmental conditions and competition from more derived ungulate groups.