This is a solid, 7.8" long Hadrosaur (Duck-Billed Dinosaur) caudal vertebra from the Two Medicine Formation of Montana. The preservation of this vertebra is excellent with very little to no weathering. There are several repaired cracks through the process, however there is no restoration and all of the bone is from the same Hadrosaur.
This vertebra measures 7.8 x 6.8" (box measurement). The centrum is 3 x 2.8 x 2.6" and the process (including anterior points of articulation) is 8.3" long (straightline).
Hypacrosaurus is a very large, Lambeosaurini Hadrsosaur that would have been almost as large as the Tyrannosaurs that it lived alongside. Like Corythosaurus, it had a tall, hollow rounded crest, although not as large and straight. It is known from the remains of two species that spanned 75 to 67 million years ago, in the Late Cretaceous of Alberta, Canada, and Montana, United States, and is the latest hollow-crested duckbill known from good remains in North America. It is estimated to have been around 9.1 meters (30 feet) long and to have weighed up to 4-5 tons.
Hypacrosaurus drawing by wikipedia user debivort. Creative Commons License