Mill Canyon Dinosaur Trailhead, UT
The Mill Canyon Dinosaur Trail is a bold experiment; there are no guards or fences here. You, the visitor, are the protector of this valuable resource. It is illegal to remove, deface, or destroy improvements, rocks, and fossils.
To reach the Mill Canyon Dinosaur Trailhead, drive 15 miles north of Moab on U.S. 191, then turn left at an intersection just north of highway mile marker 141. Cross the railroad tracks and continue 2 miles on a bladed dirt road to the Dinosaur Trailhead. The road is impassable when wet.
An essential requirement for the formation of a fossil is rapid burial by sediment after the organism dies and the soft tissue rots away, leaving the bony skeleton. This burial normally occurs in rivers, lakes, or the sea into which the carcasses of land-living animals may be washed. Two processes may then occur: (1) permineralization, where organic matter in the bones may decay and be replaced by minerals from water percolating through the sedimentary rocks; or (2) petrifaction, the bony structure may be replaced entirely by minerals. Alternatively, the bones may dissolve, leaving a hollow mold that may be filled by minerals that form a solid replica of the bone, a natural cast. Land movement and erosion may then lead to exposure of the fossil.
The BLM had a box at the trailhead containing the Mill Canyon: Dinosaur Trail (158 KB) brochure with descriptions and trail guide. The brochure file is in Adobe Acrobat .pdf format and can be printed.
Allosaurus was a large, bipedal, saurischian (lizard-hipped), meat-eating dinosaur. Heavily built, Allosaurus had powerful hind legs, relatively short but strong forelimbs, and a very large head. A massive tail must have aided in balance. The animal grew to a length of nearly 39 feet. The huge jaws were lined with large serrated, stabbing, and cutting teeth. Both hands and feet were equipped with large claws.
Stegosaurus was a moderately large four-footed, ornithischian (bird-hipped), plant eating dinosaur, which is characterized by a double row of large, alternately spaced plates that ran down its back and large spikes at the end of its tail. The animal grew to a length of 25 feet and may have weighed 1.5 tons. Stegosaurus had an extraordinarily small brain, which weighed no more than 2.5 to 2.8 ounces.
Camarasaurus was a very large, heavy bodied, four-footed saurischian (lizard-hipped), plant-eating dinosaur. It had a short skull with a blunt snout and a fairly long neck and tail. Camarasaurus grew to a length of 59 feet and the four pillar-like legs may have supported a weight of nearly 20 tons.
Camptosaurus was a moderately sized, ornithischian (bird-hipped), plant eating dinosaur, which was presumably quite nimble and fast, but otherwise quite defenseless. The animal grew to a length of around 20 feet. Hoof-like claws on both fingers and toes suggest that it often walked on all fours.