This period was directly preceded by the eruption of the Siberian Traps, which may have caused the great extinction at the end of the Permian.
Fossils from this geologic period are found in the Chinle Formation in Arizona. The notable non-dinosaur Lystrosaurus was a ubiquitous herbivore during the early part of this period and may have been fed on by Cynognathus. Sauropterygians were marine reptiles that first evolved during this period, which also saw the first ichthyosaurs. Synapsids and mammal-like reptiles declined in importance during this period, which was marked by the diversification of diapsid reptiles and saw the first ornithischians and theropods. This period was directly preceded by the eruption of the Siberian Traps, which may have caused the great extinction at the end of the Permian. For 10 points, name this first period of the Mesozoic Era, during which dinosaurs evolved.
Fossils from this geologic period are found in the Chinle Formation in Arizona.
Triassic Period 