USA, Montana, Two Medicine Formation, ca. 71,000,000 million years ago. A beautiful, huge right ulna (thinner and longer forearm bone) from a member of the hadrosaur family (Hadrosauridae). The Hadrosaurids are also known as the duck-billed dinosaurs, a herbivorous type of animal known as facultative bipeds, meaning that they walked on two legs when young and four when adults. They had large jaws with multiple rows of teeth for grinding plants. They had large noses; some of them also had crests atop their heads whose use is still unknown: maybe to attract mates, scare away predators by appearing large, or make trumpeting sounds. Hadrosaurs were scaled, not feathered, based on skin impressions; based on mass reconstructions, we think that they were muscular animals who could have outrun contemporary predators, like Tyrannosaurus Rex. This ulna shows how large these animals were - roughly 30 feet long (9.2 m) and weighed up to three tons. Well shown on this example is the olecranon process, the hook-like structure that fits into the humerus, and the styloid process, for attaching the ulnar ligament to the wrist. Size: 28.25" L x 6" W (71.8 cm x 15.2 cm)

The Two Medicine Formation is a geologic formation from 83.5 to 70.6 mya found in northwestern Montana and southern Alberta, east of the Rocky Mountains. It consists of deposits from the western shoreline of the Late Cretaceous Interior Seaway, mostly of sandstone. This interstitial zone between the nascent Rockies and the Seaway, where dinosaurs grazed and hunted along the shoreline, is one of our most fertile fossil-finding grounds, and many of our beloved dinosaur species originated in discoveries from this area. This location is famous for its hadrosaur finds, including the discovery of baby hadrosaurs and nesting sites in the early 1990s. These helped revolutionize thinking about dinosaurs, shifting them away from the old view as uncaring lizards to the currently accepted view of more bird-like creatures who lived in family units.

Provenance: Ex-Arizona collection acquired on leased land in Montana

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#117485

Stabilized/repaired, but virtually complete.