Climate - Extinctions

The climate of the Triassic world appears to have been much more uniform than today. There was no polar ice. The temperature difference between the equator and the poles appears to have been much smaller than today.

At the end of the Triassic period there were mass extinctions. Especially primitive molluscs called ammonoids were important fossil indicators for determining the relative age of Triassic strata.

Periodic large-scale mass extinctions in the history of life triggered the establishment of geologic age distinctions. The mass extinction of the dinosaurs at the end of the Cretaceous is the most famous of the five great mass extinctions. However, the third mass extinction at the end of the Paleozoic, between the Permian and Triassic, was the largest of all extinction events and had the greatest impact on Triassic life. The fourth mass extinction at the end of the Triassic caused a sharp decline in some marine and terrestrial groups, such as ammonoids, mammal-like reptiles and primitive amphibians, but had no impact on other groups.