The tracks were made from about 200 to 205 million years ago during the early Jurassic period. At this time southern Utah and Arizona were much nearer to the equator and were close to sea level. There were numerous streams and lakes throughout the area. It was a perfect habitat for the carnivorous Eubrontes dinosaurs such as the Dilophosaurus. The Dilophosaurus was the largest dinosaur of the early Jurassic period measuring 19 feet long and 6 1/2 feet tall. It had crests on each side of its head. It stood on two legs with three-toe clawed feet measuring 13 to 18 inches long. From the back of the foot protruded a dew claw or hallux. A fully grown Dilophosaurus weighed around 900 pounds.
Smaller 4 to 8 inch tracks were made by the ichnogenus Grallator such as the slender meat eating Megapnosaurus. Additional small one-inch Batrachopus dinosaur tracks of an early crocodilian have been found. Other unique features include swimming tracks, tail drags and rippled surfaces. A number of fossils have been identified in the area including those of fish, water lilies, stromatolites, ostracods, conchostracans, and conifer branches with needles still attached.
The Johnson farms dinosaur tracks lie within the Moenave formation which includes layers of sandstone, mudstone, and shale. The tracks were found at the bottom of a three-foot thick layer of sandstone overlaying mudstone. The fossil evidence indicates that the Johnson farm was located along the margins of a shallow saline lake 200 million years ago. As the water receded, dinosaurs walking through the leftover clay left impressions of their feet including scales of their skin and prints of their toes. As the mud hardened, cracks around the tracks formed. Eventually the lake level rose and buried the tracks with sand and silt. Over time the sand hardened and became sandstone thus preserving the dinosaur tracks. Within the three-foot sandstone blocks are several track-forming layers.
Enjoy exploring the galleries of Johnson farm dinosaur tracks including the 3D photo gallery.