Although tracks were first reported in a 1935 newspaper story, detailed and published scientific study did not begin until 1982. Six track layers are present containing some 1,300 footprints. More than 100 animals, mainly sauropods and theropods, are recorded. Martin Lockley is shown here demonstrating brontosaur locomotion. This series of tracks clearly records both the small front foot and larger rear foot of the animal.
Some layers have so many tracks that none are discernable.
Theropods, or two-legged carnivorous dinosaurs, are also represented in the trackways. Occasionally the claw marks of these carnivores are preserved in the Jurassic mud at the margins of what is interpreted as an ancient lake. Trackways reveal information about the animals that fossil bones do not, such as social behavior, stance, gait, and speed of travel, population composition, and ratio of predator to prey. The State Line district lies between Ft. Collins, CO and Laramie, WY and consists of about 40 Early Devonian and Late Proterozoic kimberlite dikes and diatremes.