Gorgosaurus (Greek for "fierce lizard"); pronounced GORE-go-SORE-us
Floodplains of North America
Late Cretaceous (75 million years ago)
Size and Weight:
About 30 feet long and 2-3 tons
Large size; sharp teeth; stunted arms
In many ways, Gorgosaurus was your garden-variety tyrannosaur--not quite as big (or as famous) as Tyrannosaurus Rex, but every bit as dangerous from the point of view of smaller, herbivorous dinosaurs. What really sets Gorgosaurus apart among paleontologists is that this dinosaur has left an unusually large number of well-preserved specimens (from Dinosaur Provincial Park in Alberta, Canada), making it one of the best-represented tyrannosaurs in the fossil record.
Gorgosaurus is believed to have occupied the same North American territory as another fairly generic tyrannosaur, Daspletosaurus--and some experts think it might really have been a species of yet another tyrannosaur genus, Albertosaurus. This confusion can be attributed to the fact that Gorgosaurus was discovered about 100 years ago (by the famous paleontologist Lawrence M. Lambe), at a time when much less was known about the evolutionary relationships and characteristics of theropod dinosaurs.
One interesting analysis of the growth patterns of Gorgosaurus has concluded that this tyrannosaur had an unusually long "juvenile" phase, after which it underwent a sudden growth spurt (in the course of two or three years) and achieved its full adult size. This implies that juvenile and full-grown tyrannosaurs inhabited different ecological niches during the late Cretaceous period, and probably subsisted on different prey as well. (And if you have hungry toddlers at home, imagine what it means for a one-ton dinosaur to go through a "growth spurt!")