10.7" Hadrosaur Jaw, Bone & Tendons In Sandstone - Wyoming

Hadrosaurs are frequently referred to as duck-billed dinosaurs and are members of the Ornithischian family Hadrosauridae. They were fairly common herbivores which roamed Asia, Europe, and North America during the Upper Cretaceous Period. Many species of Hadrosaurs had distinctive crests on their heads, some of which had air-filled chambers that may have produced a distinct sound. These crests may have been used for both audio and visual display purposes.

The Lance Formation of Wyoming, which dates back to the Late Cretaceous period between 66 and 69 million years ago, is home to a wide variety of both dinosaur fossils and assorted small vertebrates. During the Cretaceous, this midwestern formation would have been comprised of streams connected to the large Western Interior Seaway which split continental North America in half down the midwest. As a result of the subtropical climate and frequent rainfall, life flourished both on land and in the sea. The frequent deposition of sediment caused by the stream environment is what allows the Lance Formation to be such a fertile fossil site.

Perhaps the most famous Lance resident would be Tyrannosaurus rex, the largest North American carnivore to ever live. However, other smaller theropods also roamed the American midwest in this subtropical coastal stream system. These included the beaked Ornithomimus, a lanky running theropod with a build similar to a modern ostrich, as well as several small predatory troodonts, such as Paronychodon and Pectinodon.

Herbivorous dinosaurs also took advantage of the abundance offered by their community. Armored ankylosaurs dwelt in herds, their safety assured by their numbers, their heavy bone plating protecting most of their bodies, including their eyelids, and huge bone clubs on the ends of their tails providing them with powerful offensive capabilities. Ceratopsians like the famous Triceratops also formed protective herds, gaurding their necks with frills and horns. Their smaller relatives, the dome-headed pachycephalosaurs, were also well represented in the area. Hadrosaurs, duck-billed titans with huge batteries of plant-grinding teeth in elongated snouts, are also well known from the region.

In addition to dinosaurs, a wide variety of fishes, amphibians, lizards, snakes, turtles, champsosaurs, crocodilians, and pterosaurs have been found in the formation.