Carbonemys cofrinii is a genus of extinct turtle from the Late Cretaceous period. The only known species is C. cofrinii, which was discovered in 2005 in the Maastrichtian-age Hell Creek Formation of Montana, United States. It is one of the largest turtles ever to have lived, with an estimated shell length of 1.5 m (4.9 ft) and a weight of up to 1,000 kg (2,200 lb).
The turtle’s large size and robust build suggest that it was well-adapted to life in its aquatic environment. Its remains have been found in close association with those of other large reptiles such as crocodiles, dinosaurs, and fish. These animals would have formed part of its diet, along with smaller prey items such as molluscs and crustaceans.
Carbonemys cofrinii provides valuable insights into the ecology and evolution of Late Cretaceous turtles. Its large size indicates that some turtles were able to adapt to new niches opened up by the mass extinction at the end of the Mesozoic Era. This ability to evolve and occupy new ecological roles played an important role in their survival into the present day.