Skull 360 View See the skeleton Gorgosaurus Kingdom Animalia (animals) Phylum Chordata (animals with spinal nerve cords) Subphylum Vertebrata (chordates with backbones) Class Archosauria ("ruling reptiles") Subclass Dinosauria (extinct reptiles, "terrible lizards") Order Saurischia (lizard-hipped) Suborder Theropoda (beast-footed) Family Tyrannosauridae Carnosauria (meat-eating lizard) Genus Gorgosaurus (fearsome lizard)

Meet the Gorgosaur

Gorgosaurus means "fearsome lizard."

Gorgosaurus lived in the Late Cretaceous Period, about 70 to 80 million years ago in the western United States.

Gorgosaurus looks like its cousin T. rex. The two have a lot in common. Both were fierce carnivores, which means they ate meat instead of plants, with dozens of sharp teeth designed for biting and swallowing prey. Both were bipeds, which means they walked on two legs, and had small, muscular arms and long tails that they used to balance themselves. They both had eyes on the front of their heads which helped them look in the distance for prey, and they had a strong sense of smell, which also helped them find prey.

Gorgosaurus and Tyrannosaurus rex weren't exactly alike, however. Gorgosaurus lived several million years before T. rex, had a bony plate over its eyes and was slightly smaller than T. rex.

An adult gorgosaur was approximately 25 feet long and 10 feet tall at the hip. Gorgosaurs had strong, powerful legs, which helped them to run more than 20 miles per hour when they were chasing prey. They had three-toed feet with sharp claws.

A gorgosaur had a strong, muscular neck to support its huge head and jaws. It had more than 60 teeth 4 to 5 inches long. The teeth were serrated, which means they had notched edges like a steak knife. The teeth were not well suited for chewing, so the gorgosaur may have swallowed large chunks of flesh whole.

Interesting Things About the Gorgosaur

We can tell by the injuries found on this gorgosaur that she lived a very rough life. Her injuries included broken bones, bad teeth and a brain tumor.

The gorgosaur's injured bones included:

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A broken fibula. Instead of being strong and straight, this twisted and bumpy lower leg bone healed poorly.

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Crushed caudal vertebrae. These tail bones began to grow together as they were healing.

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A broken femur. This leg bone was so badly injured that a section of the bone tore away from the rest.

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Broken gastralia. These belly ribs helped protect the gorgosaur's vital organs. Some of the ribs healed.

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Broken scapula. This gorgosaur had a shattered scapula, or shoulder blade. A huge growth formed around the bone to stabilize it as it healed.

The gorgosaur's brain tumor may be the first one ever discovered in a dinosaur. It may have contributed to the gorgosaur's other injuries, and may even have caused her death.

Almost all the fossilized teeth of the gorgosaur are intact and attached to her jaw, but she had a bad infection in her mouth that caused her to lose some teeth.

Because of all her injuries, scientists believe this gorgosaur walked with pain and most likely had help from others in her pack to survive.

There are several things about this gorgosaur which make scientists think this may be a new species of dinosaur previously unknown to science. These include a manus claw, a sharp, curved claw similar to that of a T. rex; a furcula which leads some scientists to suggest that dinosaurs may be related to birds; and a rugose, which means bumpy, lacrimal.

Preparators working on the gorgosaur skull also found delicate structures in her nose. These structures, which are unusually well preserved, are called vestibular bulae. They may help scientists learn more about the anatomy of dinosaurs.

The Gorgosaur's Discovery

What do you do on your summer vacation? The Linsters — Cliff, Sandy, and their seven children — are a family of amateur paleontologists who hunted dinosaurs on their summer vacations. They found the gorgosaur in 1997 in Teton County, Montana.

Finding a gorgosaur is more rare than finding a T. rex. There have been only 20 gorgosaurs ever found and this one is the most complete.

The body of this gorgosaur is about 75 percent complete and her skull is about 90 percent complete. No dinosaur is discovered 100 percent complete. Due to erosion and other factors, some fossilized bones are always missing. The people who prepare the dinosaurs for exhibits create casts of the missing bones, usually from other dinosaurs that have been discovered, to fill in the missing pieces.

A Maiasaura and a Bambiraptor were found with the gorgosaur. Was the gorgosaur feasting on the Maiasaura while the Bambiraptor waited its turn?