Ancestral rhinoceroses first diverged from other perissodactyls in the Early Eocene. Rhinocerotoids diverged from other perissodactyls by the early Eocene. Ancestral rhinoceroses are held to have first diverged from other perissodactyls in the Early Eocene. The equids, like other perissodactyls, are hindgut fermenters. A 2014 cladistic analysis places both "Phenacodus" and "Meniscotherium" within stem perissodactyls. Amynodontidae ("threatening tooth") is a family of extinct perissodactyls related to true rhinoceroses. Tapiroidea is a superfamily of perissodactyls which includes the modern tapir. In consequence, there was an alternative name for the perissodactyls the nearly obsolete Mesaxonia. Unlike modern perissodactyls, chalicotheres had long forelimbs and short hind limbs. The amino acid sequences reject a connection between extant paenungulates and perissodactyls (odd-toed ungulates). The rate of increase for artiodactyls (0.74) was about a third that of perissodactyls. Despite their appearance, they have been regarded as related to elephants, not perissodactyls. Newborn perissodactyls are precocial; young horses can follow the mother after a few hours. The closest extant relatives of "Moropus" are other perissodactyls&colon; horses, rhinos, and tapirs. The stomach of perissodactyls is simply built, while the cecum accommodates up to in horses.