MEANING: Lizard crest
PERIOD: Late Cretaceous
CONTINENT: North America, Asia
Saurolophus is a large hadrosaurid dinosaur from the Late Cretaceous. It is one of the few genera of dinosaurs known from multiple continents. The type species, S. osborni, was described from Canadian fossils, and a second valid species, S. angustirostris, is represented by numerous specimens from Mongolia. Saurolophus is distinguished by a spike-like crest which projects up and back from the skull. It was a herbivorous dinosaur which could move about either bipedally or quadrupedally.
Saurolophus is from the Cretaceous. The Cretaceous is a geological period that lasted from about 145 to 66 million years ago. It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin creta, "chalk", which is abundant in the latter half of the period.
The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct flora and fauna, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth by the end of the Cretaceous, coincident with the decline and extinction of previously widespread gymnosperm groups.
The Cretaceous (along with the Mesozoic) ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary (K–Pg boundary), a geologic signature associated with the mass extinction that lies between the Mesozoic and Cenozoic Eras.
Saurolophus is a hadrosaur. Hadrosaurs, casually known as duck-billed dinosaurs, are ornithischian dinosaurs that were common in the Late Cretaceous period. Hadrosaurs were among the most dominant herbivores in Asia and North America, and toward the end of the Cretaceous several lineages dispersed into Europe, Africa, and South America.
Hadrosaurs are known for the flat duck-bill appearance of their snouts. They also had teeth in the back of their mouths that were stacked into complex structures known as dental batteries. Some derived species had large impressive crests on their heads, likely used for sexual display and communication. They were facultative bipeds, meaning they could choose to locomote using only their hind legs, or on all fours, depending on the activity and speed with which they needed to move. The young of some species walked mostly on two legs, and the adults on four.