File:Inferred Tyrannosaurus rex footprint (Laramie Formation, Upper Cretaceous; Parfet Prehistoric Preserve, Golden, Colorado, USA) 10.jpg

English: Dinosaur footprint in the Cretaceous of Colorado, USA.

Trace fossils are any indirect evidence of ancient life. They refer to features in rocks that do not represent parts of the body of a once-living organism. Traces include footprints, tracks, trails, burrows, borings, and bitemarks. Body fossils provide information about the morphology of ancient organisms, while trace fossils provide information about the behavior of ancient life forms. Interpreting trace fossils and determination of the identity of a trace maker can be straightforward (for example, a dinosaur footprint represents walking behavior) or not. Sediments that have trace fossils are said to be bioturbated. Burrowed textures in sedimentary rocks are referred to as bioturbation. Trace fossils have scientific names assigned to them, in the same style & manner as living organisms or body fossils.

Seen here is a dinosaur footprint on the basal surface of a structurally-tilted sandstone horizon. This is part of Colorado's Laramie Formation, a nonmarine, coastal plain to deltaic succession of mostly mixed siliciclastic sedimentary rocks - sandstones, siltstones, claystones, and coals.

This tridactyl track is interpreted as a possible Tyrannosaurus rex footprint. The individual was walking to the ~west.

Classification of inferred trace maker: Animalia, Chordata, Vertebrata, Reptilia, Archosauria, Dinosauria, Saurischia, Theropoda, Allosauria, Tyannosauridae

Stratigraphy: Laramie Formation, Maastrichtian Stage, upper Upper Cretaceous

Locality: outcrop along Triceratops Trail, Parfet Prehistoric Preserve, southern side of the town of Golden, Colorado, USA (~vicinity of 39° 44' 34.42" North latitude, 105° 13’ 11.71" West longitude)