English: Eubrontes giganteus Hitchcock, 1845 - theropod dinosaur footprint (~30-35 cm across at its widest) in fine-grained sandstone from the Mesozoic of Massachusetts, 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.

The dinosaur footprint shown here is in an outcrop of terrestrial siliciclastic sedimentary rocks of Late Triassic to Early Jurassic age that fill old rift valleys in Pennsylvania and adjacent states in eastern America. The rift basins formed when the ancient Pangaea supercontinent attempted to break apart, but failed. A successful breakup of Pangaea occurred during the Jurassic.

Stratigraphy: Longmeadow Formation, Newark Supergroup, Upper Triassic to Lower Jurassic

Locality: Mt. Tom Dinosaur Tracksite, north of Holyoke, Connecticut River Valley of Massachusetts, USA