Dinosaur Tracks

Eubrontes giganteus is the name of a fossil track, not a dinosaur species. A large meat-eating dinosaur pressed these prints into muddy lakeshores in what is now western Massachusetts during the Early Jurassic period. The Connecticut River Valley holds one of the densest Early Jurassic track records in North America.

Each Eubrontes giganteus track is three-toed and up to 15 inches long. That foot size suggests the animal was roughly 20 feet from nose to tail. Paleontologists believe the track-maker was a large bipedal theropod, possibly close to Dilophosaurus — a carnivore that hunted and scavenged smaller animals.

The tracks were pressed into soft mud along the shores of a shallow rift-valley lake. The Connecticut River Valley formed as the supercontinent Pangaea began to split apart about 200 million years ago, leaving long chains of lakes edged with mudflats perfect for preserving footprints.

Edward Hitchcock, president of Amherst College, began studying Connecticut Valley tracks in 1835. He catalogued hundreds of trackways and built one of the world's largest fossil track collections, now housed at the Beneski Museum of Natural History at Amherst College. Hitchcock believed the prints were made by giant prehistoric birds rather than reptiles — an idea later overturned when dinosaurs were better understood.

Massachusetts designated Eubrontes giganteus as its state fossil in 1980. The choice recognized both the scientific depth of the Valley's trackways and Hitchcock's foundational role in vertebrate ichnology.

The Dinosaur Footprints Reservation in Holyoke, managed by The Trustees of Reservations, is the easiest place to see the tracks. Hundreds of prints are exposed on a flat red sandstone shelf along the Connecticut River bank, and visitors can walk among them.

Tracks appear throughout the Valley wherever the Early Jurassic Portland Formation and Sugarloaf Arkose are exposed — in quarry walls, stream cuts, and road outcrops from Northampton south to the Connecticut border.

The Beneski Museum in Amherst holds thousands of track slabs from across the Valley, making it the best place to see the full range of Early Jurassic Massachusetts trackways in one collection.