Saurolophus was a Cretaceous Ornithopod
One of the last dinosaurs to walk the Earth, Saurolophus became extinct around 65 million years ago in the late Cretaceous Era. The fossil remains of this two-ton plant eater have been found in North America and Asia, making it one of the few dinosaurs that lived on more than one continent. All of the species were wiped out by the K-T mass extinction.
|Prehistoric Era||Late Cretaceous|
|Weight||About 2 short tons (1.8 metric tonnes)|
|Length||30-40 feet (9-12 meters)|
|Height||15 feet (4.5 meters)|
|Maximum Speed||Approximately 15-20 mph|
|Territory||North America & Asia|
Greek for “lizard crest”, Saurolophus received its name because of the 5” long crest that projected at a 45 degree angle away from the snout. These dinosaurs were foragers of the daytime. Comparisons between the skeletal remains of Saurolophus and today’s birds and reptiles suggest that Saurolophus might have been cathemeral—active during the day for short amounts of time.
What Did Saurolophus Look Like?
Paleontologists can get a good glimpse of what Saurolophus looked like 65 million years ago because there are a number of nearly complete skeletal systems on record. The most distinguishing characteristic of Saurolophus is the crest that protruded from the skull. The cranial crest was hollow and researchers only have a number of guesses as to what its primary function was. Some paleontologists believe it was a respiratory organ that could have created sounds. Others say it was for thermoregulation. Other experts contend that it was either primarily a sexual characteristic or it was a starting support for a back frill. There are a lot of possibilities when considering the function of this feature, but it was probably a combination of some of these theories.
The rest of the dinosaur wasn’t so hollow. Saurolophus weighed in at about 4,000 pounds and most of that weight was in its hindquarters and back limbs. Its hind limbs anchored it to the ground. Three-toed hoof tracks were left behind wherever it roamed. The forearms of Saurolophus were puny in comparison to the back legs, but they did allow it to forage on all fours. While walking upright, Saurolphus’s pointy long tail helped maintain balance.
What did Saurolophus eat?
By reviewing fossil records of the mouth and teeth of Saurolophus, paleontologists can say with great certainty that it was completely herbivorous. The beak for which Saurolophus and other duck-billed dinosaurs are known for had one main purpose—shearing plant material. Behind the powerful beak was a set of teeth that were continually replaced. The endless supply of teeth was an adaptation that was necessary because of the wear and tear associated with grinding fibrous plants. Examinations of Saurolophus’s skull show that it permitted a grinding motion. Saurolophus also had organs that held food in its mouth, much like the cheeks of humans, that allowed for prolonged grinding of tough material. All of these adaptations are evidence that Saurolophus was able to consume a wide variety of plants such as: conifer needles, twigs, seeds, and any other plant material. Since Saurolophus could move low to the ground on all fours, the feeding range of mature adults was from ground level to 15 feet high.
How did Saurolophus Move and Migrate?
Saurolophus was one of a handful of dinosaurs that were able to move around either on two or four limbs. It spent most of its time moving around as a bipedal on its robust legs. Saurolophus could reach its maximum speed and agility while on two limbs. Paleontological research cites evidence that suggests these dinosaurs could run as fast as 20 miles per hour. They probably travelled in herds for protection like modern-day grazing animals.
When Saurolophus needed to get its beak near the ground to graze, it would bend down and support itself with its short forelimbs. The forelimbs were ossified, which allowed them to support the dinosaur’s weight while it crawled around feeding. This ability to move around on all fours was vital because without this feeding method, Saurolophus would have had a much smaller supply of food.
Where did Saurolophus live?
Saurolophus is one of the few dinosaur genera that are known to have inhabited multiple continents and discoveries suggest that Saurolophus species covered a wide range. Fossils have been uncovered in Alberta, California, China, and Mongolia. Asian species that have been discovered are slightly larger than those of America. The species discovered in North America were only limited in range by the Pacific Ocean and the Western Interior Seaway that stretched from the Gulf of Mexico to the Arctic Ocean during the Late Cretaceous period. The divided landmass that Saurolophus inhabited is now known as Laramidia, which stretched from Mexico to Alaska. The eastern side of the Western Interior Seaway, Appalachia, is believed to have been void of Saurolophus since there haven’t been any discoveries as of yet.
The first species of Saurolophus, S. osborni, was discovered by Barnum Brown in 1911 in Alberta, Canada. The skeleton was nearly complete, making it the first Canadian discovery to supply such a large percentage of bones. It was found in the Upper Cretaceous Horseshoe Canyon Formation (Edmonton Formation at the time of discovery) on the Red Deer River. It was the first duck-bill dinosaur to be found that had sclerotic rings, which are rings of bones that surround the eye. Barnum Brown’s discovery can be seen today in the American Museum of National History.
More than thirty years after Brown’s discovery, scientists in China dug up what they believed were new species of Saurolophus. When their findings were verified, two new species were added to the genus. Then in 2010, partial skeletons were discovered in California and attributed to Saurolophus. One skull was instead deemed an Edmontosaurus, but the remaining fossils are thought to be part of the Saurolophus genus and have been named S. “morrisi”. The name isn’t official yet, though, because the study hasn’t been published.
The Importance of Saurolophus
Since fossils are plentiful and they were discovered early on in the hunt for dinosaurs, Saurolophus is an important reference for other hadrosaurs. In fact, one of the most abundant hadrosaurids in all of Asia is S. angustirostris, a large Saurolophus. Dozens of new discoveries have been compared and contrasted with Saurolophus for classification purposes.
Saurolophus is also an important genus for dinosaur research because it was one of the genera that became extinct at the end of the Cretaceous period. Scientists are always seeking to know more about the event that caused the mass extinction of dinosaurs, so remains like those of Saurolophus that were fossilized during the extinction event may hold important clues.