Petrified Forest National Park is one of the best places on earth to study all kinds of fossils from the Triassic Period. The Triassic is a time when giant reptiles including the earliest dinosaurs and other crocodile like creatures were vying to become the world’s dominant land animals. Lots of other creatures originated during this time as well including frogs, turtles, pterosaurs, true mammals, and ichthyosaurs.
Postosuchus
- Petrified Forest has fossil wood from nine different geologic layers
- Petrified Forest has some of the earliest “dated” dinosaurs in the fossil record of North America, at 223 million years ago.
- Petrified Forest has over 90 species of fossil plants and animals that were first named from our rocks.
- Petrified Forest preserves fossils of everything from microscopic plant pollen to 20 foot long crocodile-like animals called phytosaurs.
- The largest carnivorous land animals from Petrified Forest are not dinosaurs; instead they are armored “dinosaur-like” crocodile ancestors including one called Postosuchus.
- Triassic dinosaurs were small and probably preyed upon by animals like Postosuchus
All these fossils are contained in about 20 million years of rock layers deposited by ancient river systems 225 to 205 million years ago, which is about a third of the entire Triassic time period. These fossils and other clues provide direct evidence of ecosystem changes through time, which are responses to ancient global climate changes.
