Rutherford, NJ Newark Supergroup strata are famous for the large variety of fossils found in strata formed mostly in ephemeral to deep lakes. Some examples are shown in this photo album. At the same time, the convergence of plates on the other side of North America produced a series of gentle but very broad sags in the crust that filled with a relatively thin sequence of continental strata called the Chinle Group. These broad basins extend from western Texas north to Alberta. Triassic Chinle Group outcropping at Petrified Forest National Park.
Red cylinders are segments of petrified logs.
A great many examples of Archosauriformes have been found in the Newark Supergroup and the Chinle Group. A good representative is Euparkeria who you have seen in previous lectures. Almost all of the Archosauriformes from the Newark and Chinle, however, belong to a more advanced sub-group within. Ankle types within the Archosauriformes fall into three broad categories. First the primitive condition in which the ankle beds at several places in a rather flexible and loose way.