|Similar Eodelphis, Didelphodon, Deltatheroida, Alphadon, Deltatheridium|
Stagodontidae is an extinct family of carnivorous metatherian mammals that inhabited North America during the late Cretaceous.
Currently, the family includes four genera, Eodelphis, Didelphodon, Fumodelphodon and Hoodootherium, which together include some seven different species. In addition, the Cenomanian species Pariadens kirklandi might be a member of the family. Stagodontids were some of the largest known Cretaceous mammals, ranging from 0.4 to 2.0 kilograms (0.88–4.41 lb) in mass. One of the most unusual features of stagodontids are their robust, bulbous premolars, which are thought to have been used to crush freshwater mollusks. Postcranial remains suggest that stagodontids may have been semi-aquatic. The most well described forms are found in Laramidia, but they are also present on Appalachian sites, further leading credence to their aquatic habits.
The evolution of Didelphodon and other large stagodontids (as well as large deltatheroideans like Nanocuris) occurs after the local extinction of eutriconodont mammals, suggesting passive or direct ecological replacement.
Stagodontids were once thought to be closely related to the Sparassodonta, but later studies suggest they belong to a more ancient branch of the metatherian family tree, possibly closely related to pediomyids, being in particular closest to Pariadens, which forms the immediate outgroup to Stagodontidae. Stagodontids are last known from the Maastrichtian, and are thought to have gone extinct in the K-T Extinction.