Earth's Triassic Period

The Triassic Period followed the Permian Period and lasted from around 251 to 199 million years ago. The Triassic begins the three-stage Mesozoic Era which is most known for the evolution and proliferation of the dinosaurs. The beginning of the Triassic was marked by a series of major extinctions as have been previously described in the discussion of the Permian Period.

Continental drift was continuing into the Triassic and the major continents were still fused into one giant landmass called Pangaea. However, the westward encroachment of a large body of water called the Tethys Sea began to widen the coastline of Pangaea and reduce some of the desert conditions at its interior. The rest of the Earth continued to be covered by the vast Panthalassa Ocean. Although the deserts began to shrink during the Triassic, the climate was still relatively hot and dry due to the distance between shorelines and continental interiors. The continental climate became more seasonal, as it had during the early Permian Period, with hot summers alternating with cold winters. There is little evidence for glaciation at the poles during the Triassic Period, which meant that sea levels would have been higher than they were during the Permian Period.

As in the Permian Period, tree-ferns and other plants that reproduced through spores and required moist habitats did not fare well in the hot and dry Triassic climate. As in the late Permian, forests were now dominated by conifers and other gymnosperms: plants that use seeds in order to reproduce. Regional diversity was able to progress much more than in the Permian due to the encroachment of the Tethys Sea to the interior of Pangaea as well as a more active storm cycle. With the comeback of widespread vegetation and forest over once desert areas came the resurgence of large herbivores.