Section 5: Mesozoic Era
After the Paleozoic Era ended about 248 million years ago, the Mesozoic (mez-a-zoe-ik) Era began and lasted until about 65 million years ago, a length of about 183 million years. The Mesozoic Era is sometimes called the “Age of Reptiles” because during the millions of years of this era, many kinds of reptiles developed. Some were fish-like creatures that swam in the ocean waters, some were flying reptiles, and some lived on the land.
The most famous reptiles of all time were the dinosaurs. Fossils from more than a dozen different kinds of dinosaurs have been found in North Dakota.
An example of a large sea reptile that lived in the area was the mosasaur (mos-a-sor). This giant lizard was a carnivore that hunted other marine (sea) animals.
One of the flying reptiles that lived in this area was the carnivorous Pteranodon (ter-an-a-don). It had a long neck, a long beak, and a wing-span of about 20 feet from tip to tip.
The most common dinosaur found in North Dakota was Triceratops (try-sair-a-tops). This strange-looking reptile had a huge head with a big horn above each eye and a smaller horn on its nose. It also had a bony plate at the back of its skull that looked like a high collar sticking up from its neck. It was an herbivore that could weigh as much as five tons (10,000 pounds).
Most of the dinosaurs that lived in North Dakota were herbivores, but one of the best-known carnivores was Tyrannosaurus (ty-ran-a-sor-us) rex, a huge dinosaur that walked on two powerful legs. A full-grown Tyrannosaurus rex was about 40 feet long, stood about 20 feet tall, and weighed about six tons (12,000 pounds). Its arms were only about three feet long.
Tyrannosaurus rex had very strong jaws about four feet long, and it had 50 to 60 sharp teeth. Some of the teeth were about six to 10 inches long, and if teeth would break, new teeth would replace them. In one bite, the Tyrannosaurus rex could eat up to 500 pounds of meat.
Although not a dinosaur, one of the latest ancient reptiles to be dug up in North Dakota was at a site near Linton, North Dakota. It was a champsosaur (champ-sa-sor) which lived in swamps and looked something like a crocodile.
North Dakota Heritage Center & State Museum
Adaption Gallery: Geologic Time
Examples and exhibits of the mosasaur, Pteranodon, Triceratops, and champsosaur are on display in the Adaption Gallery: Geologic Time at the North Dakota Heritage Center & State Museum in Bismarck, North Dakota.
To learn more about the story of geology and early life in North Dakota, visit https://statemuseum.nd.gov/exhibits/adaptation-gallery. The Adaption Gallery: Geologic Time introduces visitors to North Dakota as it was in the geologic past.