Pentaxodontomorpha

Pentaxodontomorpha is an extinct infraorder of neoplagiaulacoid multituberculate mammals. These animals are known from the Late Cretaceous to the Paleogene periods. Fossil evidence suggests they were widespread in North America and Europe. Pentaxodontomorphs were characterized by their distinctive dentition, particularly a large, ridged lower premolar, a common trait among multituberculates but often proportionally larger and more robust in this group. Their teeth indicate a diet likely consisting of seeds, nuts, and possibly tough plant material, suggesting they were herbivores or omnivores. The group includes families such as the Pentacodontidae and possibly the Cimolodontidae, though the precise phylogenetic placement of some multituberculate families within or outside of Pentaxodontomorpha is subject to ongoing research and debate. Fossil discoveries, primarily consisting of jaw fragments and isolated teeth, have provided insights into their morphology and evolutionary relationships within the broader multituberculate radiation. Pentaxodontomorphs represent an important component of early mammalian ecosystems, filling ecological niches that were later occupied by a more diverse range of placental mammals following their extinction.