Tyrannosaurus rex is perhaps one of the best-known, and one of the largest of all carnivore dinosaurs. It lived during the Late Cretaceous Period, 70 million years ago. Tyrannosaurus rex was a fierce predator that walked on two powerful legs. This carnivore had a huge head with large, pointed, replaceable teeth and well developed jaw muscles. It had small arms, each with two fingers. Each bird-like foot had three large toes, all equipped with claws (plus a little dew claw on a vestigial fourth toe). Tyrannosaurus rex had a slim, stiff, pointed tail that provided balance and allowed the animal to make quick turns while running. Tyrannosaurus neck was short and muscular. It was a strongly-built theropod with a stiff, pointed tail which was used as a counterbalance for its enormous head. The rear part of the tail was stiffened by interlocking vertebral zygopophyses (interlocking bony structures projecting forwards and backwards from the neural arches, interlocking one vertebra into another). Tyrannosaurus jaws were up to 4 feet (1.2 meters) long and had 50 to 60 thick, conical, bone-crunching teeth that ranged in size from very small to over 9 inches (23 cm) long. Adults had a variety of sizes of teeth in their jaws at one time, as teeth were broken off new ones grew in to replace them.
Class Order: Saurischia
Name Meaning: Tyrant Lizard King
Period: Late Cretaceous 70 -65 million years ago
Location: North America
Length: 40 feet (12.20meters)
Weight: 6- 7 Tons
One Tyrannosaurus rex was found with some teeth up to 13 inch (33 cm) long. It could eat up to 500 pounds (230 kg's) of meat and bones in one bite! Tyrannosaurus rex had a wrap-around overbite; when it closed its mouth, the upper parts of the lower jaw's teeth fit inside the upper teeth. Tyrannosaurus rex was one of the largest terrestrial carnivores of all time. It stood approximately 15 feet high and was about 40 feet in length, roughly six tons in weight.
Good Tyrannosaurus rex specimens, however, are hard to come by, Berkeley's mount is 90% complete, one of the best specimens found to date. Other specimens around the country range from about 10% to 80% complete; missing ribs and tail bones are common. Tyrannosaurus teeth were massive, resembling a railroad spike. Tyrannosaurus teeth were designed to crush bone and tear flesh. Its jaws were 16 times stronger than today’s alligator. Its teeth were solidly anchored to withstand pressures from every direction during an attack. Tyrannosaurus had excellent eye sight, supported by its large visual lobes on its skull. Tyrannosaurus rex also had depth perception (since both eyes faced forwards on the front of its skull, and not placed on the sides. Predators in general have evolved depth perception to easily track their prey. Tyrannosaurus rex had excellent olfactory receptors and was able to detect a possible meal from far away. Like many modern predators in the wild such as lions, Tyrannosaurus rex probably didn’t eat every day. Instead after killing an animal, it gorged itself on the flesh and this would have hold the dinosaur for a few days before returning to the carcass or go in the hunt for a new kill. It is possible that Tyrannosaurus was also a scavenger, feeding on animals killed by other predators. Tyrannosaurus rex fossils have been found in western North America and Mongolia. Approximately 30 incomplete Tyrannosaurus rex specimens have been recovered. The first Tyrannosaurus rex was first discovered by Barnum Brown in 1902, in Hell Creek, Montana, USA, North America.