Dating of the triassic period
This took the form of a giant "Pac-Man" with an East-facing "mouth" constituting the Tethys sea, a vast gulf that opened farther westwards in the mid-Triassic, at the expense of the shrinking Paleo-Tethys Ocean, an ocean that existed during the Paleozoic.
The remainder was the world-ocean known as Panthalassa ("all the sea").
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).
The shelled cephalopods called Ammonites recovered, diversifying from a single line that survived the Permian extinction.
Thus Triassic stratigraphy is mostly based on organisms living in lagoons and hypersaline environments, such as Estheria crustaceans.
The Triassic climate was generally hot and dry, forming typical red bed sandstones and evaporites.
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.