Fossil Tracks In The Moenave

A rare occurrence of running dinosaurs has recently been documented in the Moenave Formation near Cameron, Arizona, dating from the Early Jurassic, about 180 million years ago The tracks show strides of 16 feet and an estimated speed of 20 miles per hour. These tracks probably belonged to Dilophosaurus, which is the first large carnivorous dinosaur known to appear anywhere in the fossil record, and may be closely related to the generalized megalosaurs found worldwide.



There are at least 34 dinosaur trails
(over 300 tracks) in this location with a total of three other running dinosaur tracks. The speeds of the three small trackways are estimated to be from 8-14 miles per hour. All of the footprints are thought to be made by small theropods (meat-eating dinosaurs), possibly including Syntarsus, Coelophysis and Segisaurus. This amazing tracksite was actually first discovered in the 1930's by the famed Roland T. Bird, who was told about it by an elderly Navajo man describing giant "bird" tracks in the desert. Bird made no map of the site but did have a photograph taken of himself kneeling next to the tracks. The site was lost for the ensuing 50 years until Scott Madsen, working as a preparator at the Museum of Northern Arizona, studied the photo and went out into the general area east of Cameron on the Navajo reservation in 1986. After driving around for several days, he recognized the landmarks from the photo and indeed the site was found. The Cameron site is one of six documented Early Jurassic track sites that are known to exist in northeast Arizona. Permission from the Navajo Nation is always required before accessing their land.




The environment of the Wingate Sandstone phase of the Moenave Formation was probably hot and dry with occasional period of river deposition to form the Moenave. Various tracks found over the years in the Kayenta have been given dinosaurs name such as Coelophysis, Dilophosaurus, Eubrontes, Anchisauripus, Grallator, Kayentapus, Hopiichnus, Navahopus, Megalosaurus, Syntarsus and Scutellosaurus though some of these names, based on tracks, may not be entirely valid. (http://www.t-rat.com/Pages/JurassicPeriodAz.html)