Little is known of Triassic (from 245-208 million years ago) and Jurassic (from 208-146 million years ago) rocks of Oklahoma, because few of these rocks are exposed at the surface. What little is exposed is limited to the western half of the Panhandle, particularly in the area of Black Mesa.
From what is exposed, Triassic rocks are similar to that of the Permian, as most consist of bright red and orange sandstones and shales. This implies that the climatic conditions in Oklahoma during the Triassic Period were about the same as they were during the Permian, probably fairly hot and arid. The only difference is that there was no inland sea covering any part of Oklahoma during the Triassic as there was during much of the Permian. All rocks of Triassic age are what geologists consider being non-marine in origin. Triassic rocks were most likely formed in ancient rivers and flood plains away from the ocean. In fact, unlike the Paleozoic Era (which includes the Cambrian through Permian Periods) the Mesozoic Era (Triassic, Jurassic, and Cretaceous) is represented by relatively low sea-level stands. Ancient oceans rarely covered Oklahoma, except for some brief periods during the Cretaceous. Even though the Mesozoic Period of Oklahoma does not have many rocks of marine origin, rocks of this age do contain a large assortment of vertebrate remains, particularly dinosaurs. This is why the Mesozoic is often called the ‘Age of Dinosaurs’.
As one may gather, non-marine conditions continued from the Triassic into the Jurassic. Differences between these two periods do exist, however, in that there was less hematite deposited during the Jurassic, so that Jurassic sandstones, siltstones, and shales are typically gray in color, rather than red. This may indicate that the Jurassic climate was more humid and wet, compared to the Triassic.
One of the most famous Jurassic sedimentary rock units, the Morrison Formation, is well exposed around Black Mesa, and contains one of the most important assemblages of dinosaur remains found in North America. Besides a vast number of collected dinosaur bones, dinosaur footprints can also be viewed around Black Mesa State Park. Other remains collected from the Morrison Formation include crocodiles, turtles, and fish.
To see what Oklahoma was like during this period go to the Paleogeography of the Triassic-Jurassic.
Reference: Johnson, K. S. 1996. Geology of Oklahoma, p. 1-9. In, K. S. Johnson and N. H. Suneson (eds.), Rockhounding and Earth-Science Activities in Oklahoma. Oklahoma Geological Survey Special Publication 96-5.