Do all these carnivores fit together?

Do all these carnivores fit together?

	Tyrannosaurus rex Height: 12 to 15 meters Weight: 6 tons Fear factor: fangs up to 40 cm long Lived: 65 million years ago Where: North America
	Gigantosaurus Height: approx. 14 meters Weight: 8 tons Fear factor: teeth up to 20 cm long Lived: 95 million years ago Where: present-day Argentina
	Spinosaurus Height: up to 17 meters Weight: 8 tons Fear Factor: Long, crocodile-like jaw Lived: 100 million years ago Where: present-day Argentina, Morocco, Tunisia and Algeria

Illustrations by Joe Tucciarone

However, among the longest dinosaurs, a vegetarian emerged victorious. Herbivorous sauropods eclipsed carnivorous theropods; today, most scientists believe that the longest dinosaur was the Argentinosaurus.

Length: up to 37 meters Weight: 100 tons Fear Factor: ???? Lived: 65 million years ago Where: South America

Paleontologists only have fossils to determine dinosaur size, and these are often damaged or incomplete. Bones are often missing from numerous specimens, so scientists must estimate the animal's total size based on partial skeletons, such as fragments of the Spinosaurus skull.

Greg Erickson of Florida State University (USA) believes that mass, not length, is the best standard for comparing dinosaur size, as this isn't a problem with differently shaped animals. He believes mass can best be estimated by measuring the circumference of the femur, which bore the largest portion of the animal's weight.

Reevaluating Spinosaurus's size is "important ," Erickson told the LiveScience authors. Spinosaurus was likely much longer, and perhaps heavier, than Tyrannosaurus rex and other large theropods.