Males are often more than five times heavier than the females, making them among the most sexually dimorphic of all mammal groups.

Like most Mesozoic mammal groups, early trechnotherians are known mainly from their teeth.

Primates are one of the oldest of all surviving placental mammal groups.

Most mammal groups are represented in the Collection.

Tillenius continued to study museum methods, diorama construction and mammal groups.

Laurasiatheria is a mammal group, with species put together based on DNA analysis.

As with many mammal groups, even-toed ungulates first appeared during the Early Eocene (about 54 million years ago).

At the beginning of the Eocene, several new mammal groups arrived in North America.

The only omitted extant mammal group is the egg-laying monotremes.

The colubrids, one of the more common snake groups, became particularly diverse due to preying on rodents, an especially successful mammal group.