Species: Eubrontes, Grallator, possibly one or two Anchisauripus
Location: Erving, Massachusetts
Size: 35” x 39” largest track is approximately 19” from middle toe to the heel.
Recently and legally collected! This double-sided treasure sports two trackways! There are a mix of species, predominantly Fossil Eubrontes Tracks with a few grallators. These were Jurassic meat-eating theropods! The Eubrontes Tracks are plentiful and average at 17”-18” on each side. The slabs is approximately 39” x 35”. It’s massive!
The raised impressions are definitely the dominant Trackway. While the concave impression are nice and distinct, they don’t quite pop like the convex impressions!
Eubrontes is the name of the large footprints, identified by their shape, and not of the genus or genera that made them, which is as yet unknown. They are most famous for their discovery in the Connecticut River Valley of Massachusetts in the early 19th century. They, among other footprints, were the first known non-avian dinosaur tracks to be discovered in North America, though they were initially thought to have been made by large birds.
The footprints were first described by Edward Hitchcock, a professor of Amherst College, who thought they were made by a large bird. He originally assigned them to ichnotaxon Ornithichnites in 1836, then Ornithoidichnites in 1841, before coining Eubrontes in 1845. The name means "true thunder," probably referring to the supposed weight of the animal impacting on the ground.
in 1858 Hitchcock still described the tracks as those of "a thick-toed bird," since there was no evidence of tail drag marks. But by the time that Richard Swann Lull began working on the tracks in 1904, they were thought to belong to a dinosaur. Lull originally thought they were from a herbivore, but by 1953 he concluded they were from a carnivorous theropod. Many later authors have agreed with this interpretation, but some have suggested that they are from a prosauropod. Regardless, they are almost certainly saurischian.
A typical Eubrontes print is from 25–50 cm long, with three toes that terminate in sharp claws. It belongs to a biped that must have been over one metre high at the hip and from 5–6 metres long. In the 1960s Edwin Colbert and others supposed that a large heavy carnivore like Teratosaurus (then considered to be a dinosaur) made the track, but a possible candidate is Dilophosaurus, a large theropod related to Coelophysis, or a close relative such as Podokesaurus. However no Dilophosaurus fossil material is associated with Eubrontes tracks. The tracks may also be from a plateosaurid.
Grallator is an ichnogenus (form taxon based on footprints) which covers a common type of small, three-toed print made by a variety of bipedal theropod dinosaurs. Grallator-type footprints have been found in formations dating from the Late Triassic through to the early Cretaceous periods. They are found in the United States, Canada, Europe, Australia and China but are most abundant on the east coast of North America, especially the Triassic and Early Jurassic formations of the northern part of the Newark Supergroup. The name Grallator translates into "stilt walker", although the actual length and form of the trackmaking legs varied by species, usually unidentified. The related term "Grallae" is an ancient name for the presumed group of long-legged wading birds, such as storks and herons. These footprints were given this name by their discoverer, Edward Hitchcock, in 1858.
Grallator footprints are characteristically three-toed (tridactyl) and range from 5 to 15 centimeters (or 2 to 6 inches) long. Though the tracks show only three toes, the trackmakers likely had between four and five toes on their feet. While it is usually impossible to match these prints with the exact dinosaur species that left them, it is sometimes possible to narrow down potential trackmakers by comparing the proportions in individual Grallator ichnospecies with known dinosaurs of the same formation. For example, Grallator tracks identified from the Yixian Formation may have been left by Caudipteryx.