toxodontids

Toxodontids were a family of extinct South American ungulates that lived from the early Miocene to the end of the Pleistocene epoch. They were part of the notoungulate order, a diverse group of hoofed mammals endemic to South America. Toxodontids are characterized by their robust build, large size, and peculiar skull morphology. The most famous genus, Toxodon, was comparable in size to a modern rhinoceros.

These animals possessed broad, flattened heads with eyes positioned high on the skull, suggesting an adaptation for grazing in open environments, possibly with their heads low to the ground to avoid predators. Their teeth were hypsodont, meaning they had high crowns, indicating a diet of tough, abrasive vegetation. The dental formula and arrangement were unique, with large, continuously growing incisors and canines, and molars that had a distinctive trilobate pattern in unworn specimens.

Toxodontids were herbivores and likely played a significant role in their ecosystems. Their evolutionary history is deeply intertwined with the isolation of South America, where they diversified in the absence of large placental mammals like elephants and rhinos. Fossil evidence suggests a wide distribution across various South American habitats, from grasslands to more wooded areas. The extinction of toxodontids coincides with the arrival of humans in the Americas during the late Pleistocene, and while direct evidence of predation is scarce, human hunting is considered a potential contributing factor to their demise, alongside climate change.