Late Cretaceous

Hell Creek Formation

Harding County, South Dakota, USA

Excellent 0.7 inch tooth.

Reptile, Crocodilian.

Crocodilians date back to the Triassic Period and were quite diverse across the Mesozoic and Early Cenozoic Eras.  Most of the Cretaceous forms were small to medium-sized as indicated by this tooth but there was a 50-foot crocodile, Deinosuchus, living around this time from Texas east to North Carolina.  There were giant crocodiles from earlier in the period in northern Africa (Sarcosuchus) as well.