During the Permian Period the area that is now Palo Duro Canyon State Park, was a nearly-flat land surface along the edge of a restricted sea. The scarcity of fossils in the Quartermaster Formation indicates that plant and animal life was sparse. The environment was probably unsuited for plant life. It is thought that groundwater near the surface evaporated, leaving large amounts of salt as a residue. Since plants could not grow, animals would not have frequented the area either.
Figure 6. Headward erosion by the Pecos, Colorado, Brazos, Red and Canadian Rivers isolate the High Plains by the end of the Pleistocene (10,000 years ago) and cut Palo Duro Canyon.
Fossils and rocks of the Tecovas Formation indicate that the sediments were deposited in a swamp and stream environment ([Figure 7]). As time went on and the land continued rising, the climate became drier and some of the earlier life forms disappeared.
Remains of Metoposaurus (‘Buettneria’), the last of a long line of giant amphibians, are found here. These animals lived in large ponds. Metoposaurus buried themselves in the bottom of a pond and waited for fish to pass. With the aid of a third eye in the middle of its head, the animal could direct its huge mouth to its prey. Metoposaurus was so bulky that it is thought that it did not leave the water because its weak legs could not support its weight on land.
Living in shallower areas of the swamp were a group of semiaquatic reptiles known as phytosaurs. Phytosaurs looked very much like giant crocodiles with a nostril on the top of their heads, which permitted them to lie submerged just below the surface of the water. They probably fed on fish and smaller reptiles. Phytosaurs reached a length of 50 feet.
A heavily armored aetosaur, Desmatosuchus also lived in the Park area during the Triassic. They attained a length of about 10 feet. These reptiles probably were herbivorous (plant eating). A unique feature of Desmatosuchus was a fringe of backward-pointing horns around their necks. These possibly served to protect them from the carnivorous (meat eating) phytosaurs.
Figure 7. Life of Late Triassic time, showing restorations of the animals and plants that are now found as fossils in the Chinle beds of New Mexico and Arizona. In the water is the gigantic labyrinthodont amphibian, Eupelor, an animal some six feet or more in length. Lying on the bank is the crocodile-like thecodont reptile, Phytosaurus, large individuals of which may be twenty or thirty feet long. Behind the phytosaur, in the distance, is the armored thecodont, Desmatosuchus, ten feet long, and in the foreground is the small, bipedal thecodont, Hesperosuchus. In the left background are two individuals of the early saurischian dinosaur, Coelophysis, reptiles about ten feet in length. These animals lived in a tropical environment of moderate topography, crossed by many sluggish rivers and dotted with lakes. Numerous volcanoes rose above the general level of the land. Large, araucarian trees were abundant, stout scouring rushes or horsetails ten or fifteen feet high were everywhere, and the ground was covered with abundant ferns.
Also found in the Tecovas and Trujillo formations are fossil lung-fish teeth. Lung-fish are a type of fish that can breathe air, enabling them to move from pond to pond. Footprints of a chicken-sized dinosaur have also been found. The Middle Triassic flora was dominated by giant palm-like trees. Also found are remains of a few large ferns and horsetails. As the climate became drier and the swamps began to disappear, coniferous (evergreen) trees such as Araucarioxylon became plentiful. These trees can be found in the canyon today as petrified wood.