Dramatic climate change was previously proposed to be responsible for the disappearance of turtles 71-million-years ago, because they were considered to be "climate-sensitive" animals. Results of this research, however, show that the disappearance of turtles came before the climate cooled and instead closely corresponds to habitat disturbances, which was the disappearance of wetlands.

Source: Dinosaur-era climate change study suggests reasons for turtle disappearance