wELCOME TO THE MILL CANYON DINOSAUR TRACKSITE
The Mill Canyon Dinosaur Tracksite contains a diverse assemblage of fossilized tracks. More than 300 individual tracks have been discovered, including tracks from long-necked herbivores, several types of carnivorous dinosaurs (including sickle-clawed "raptors") and crocodiles.
This site is one of the largest and most diverse tracksites known from the Early Cretaceous time period in North America.
Environment
Approximately 112 million years ago, this area was a mud flat where a shallow lake was drying up. The mud flat was covered by a 1-foot-thick layer of lime mud, and the mud was covered by a mat of algae. The algae formed when the mud flat was still under water. The bumps on the surface of the track layer are petrified colonies of algae. Slide marks on the track layer show that animals sometimes slid on the soft mud of the flat. A dinosaur coprolite (fossilized dung) with pieces of leaves in it was found on the track layer. From this discovery, we know that land plants grew near the lake. Seed ferns and conifers were common land plants at this time in geologic history. Fossilized tracks and traces show that this area was visited by a diverse array of dinosaurs, reptiles, birds, and mammals.
how is this site unique?
Many of the dinosaur tracksites in the Moab region are preserved in the Jurassic sandstones exposed in the area. At these other sites, only one or two types of tracks often are found preserved at any single location. The Mill Canyon Dinosaur Tracksite is Lower Cretaceous in age and represents a different environmental setting than the nearby Jurassic Period sites. This site also contains as many as 10 different kinds of tracks, or "ichnotaxa" representing dinosaurian, crocodilian, and avian track makers. Several of these tracks are either new to North America or are from animals not currently known to science from skeletal fossils in this area.
why is this site important?
This site is the largest and most diverse tracksite known in the Cedar Mountain Formation. Collaborative research efforts indicate that the Mill Canyon Dinosaur Tracksite is one of the most significant Early Cretaceous tracksites in the world. As research continues at this and other sites, new interpretations will come to light to help us better understand the life and times of the Early Cretaceous dinosaurs of eastern Utah.
large theropod tracks
The large, well-preserved tracks in front of you are the beginning of a 17-step trackway of a very large, carnivorous dinosaur. Tracks of a similar dinosaur have also been found in central Texas. The tracks here are about 16-20 inches long and are from a dinosaur that was at least 8 feet tall at the hip. The intriguing thing about these tracks is that they indicate the presence of a very large dinosaur for which we currently have no skeletal evidence. A very large meat-eater remains to be found out there.
Name of Track: Irenesauripus / Early Cretaceous (~142 million years ago)
medium theropod tracks
The trackway in front of you is that of a medium-sized carnivorous dinosaur. Similar tracks have also been found in Wyoming. The tracks here are about 7-14 inches long and are from a dinosaur that was about 6 feet tall at the hip. We do not know exactly what kind of dinosaur made these tracks (there are several of this size and foot morphology in the Cedar Mountain Formation), but one possibility is the relatively mid-sized theropods like Ornithomimids.
Name of Track: Carmelopodus-like / Early Cretaceous (~112 million years ago)
dromaeosaur tracks
The tracks in front of you are the first dromaeosaur tracks that have been found in North America! This short trackway was made by a dromaeosaurid theropod, probably a large Deinonychus. Notice that there are only two toes preserved in each track; this is because the inner toe on each foot (digit II) possessed a huge sickle claw and was held up off the ground as the animal walked. This dromaeosaur's tracks are 8.7 inches long and indicate an animal just under 4 feet tall at the hip.
Name of Track: Dromaeosauripus / Early Cretaceous (~112 million years ago)
The landscape you see here represents over 200 million years of geologic history here in Southeast Utah!
