ERA PERIOD AGE (of start) Cenozoic Quaternary 1.6 my Tertiary 65 my Mesozoic Cretaceous 140 my Jurassic 205 my Triassic 250 my Paleozoic Permian 290 my Carboniferous 355 my Devonian 410 my Silurian 438 my Ordovician 510 my Cambrian 540 my

Triassic 250 - 205 million years ago Life Dominant life includes: Dinosaurs, early mammals (small, rat-like), gymnosperm forests First dinosaurs and mammals Dinosaurs quickly diversify Climate The climate was mainly dry with monsoons in some areas, accompanied by a low sea level. Monsoons are winds that shift directions, causing rainy periods and dry periods. Southeastern Asia currently has a monsoon season. Geology The supercontinent, Pangea, was sectioned into two major land masses, Gondwana in the north (Africa, South America, India, Antarctica, Australia) and Laurasia in the south (North America and Europe). The main rock types/ deposits in PA are sandstone, diabase and shale. Major erosion of the Appalachians was occuring during this time.