Dating of the triassic period
Archosauromorph reptiles – especially archosaurs – progressively replaced the synapsids that had dominated the Permian.
Although Cynognathus was a characteristic top predator in earlier Triassic ( Olenekian and Anisian) Gondwana, and both Kannemeyeriid dicynodonts and gomphodont cynodonts remained important herbivores during much of the period, by the end of the Triassic, synapsids played only bit parts.
In marine environments new, modern types of corals appeared in the Early Triassic, forming small patches of reefs of modest extent compared to the great reef systems of Devonian times or modern reefs.
The shelled cephalopods called Ammonites recovered, diversifying from a single line that survived the Permian extinction.
The remains of fish, and various marine reptiles (including the common pachypleurosaur Neusticosaurus, and the bizarre long-necked archosauromorph Tanystropheus), along with some terrestrial forms like Ticinosuchus and Macrocnemus, have been recovered from this locality.
All these fossils date from the Anisian/ Ladinian transition (about 237 million years ago).
Pangea's large size limited the moderating effect of the global ocean; its continental climate was highly seasonal, with very hot summers and cold winters.(Stanley, 452-3) It probably had strong, cross- equatorial monsoons.(Stanley, 452-3) In the Triassic, three categories of organisms can be distinguished: holdovers from the Permian-Triassic extinction, some new groups which flourished briefly, and new groups which went on to dominate the Mesozoic world.During the Carnian (early part of the Late Triassic), some advanced cynodont gave rise to the first mammals.At the same time the Ornithodira, which until then had been small and insignificant, evolved into pterosaurs and a variety of dinosaurs.Among other reptiles, the earliest turtles, like Proganochelys and Proterochersis, appeared during the Norian (middle of the Late Triassic).The Lepidosauromorpha - specifically the Sphenodontia, are first known in the fossil record a little earlier (during the Carnian).