Mesozoic Era Late Cretaceous Period Dinosaurs Tyrannosaurus


Quick Facts
Name Meaning:Tyrant Lizard
Distribution:Mid west U.S. and Canada (Alberta-Texas)
Time Period:Late Cretaceous, 67-65 Ma
Length:40ft (12m)
Weight:7.5 tons
Habitat:Forests, Swamps

Linnaean Classification
Cladistic Classification
  • Dinosauria
    • Saurischia
      • Theropoda
        • Tetanurae
          • Avetheropoda
            • Coelurosauria
              • Tyrannoraptora
                • Tyrannosauroidae
                  • Tyrannosauridae
                    • Tyrannosaurinae
                      • Tyrannosaurus rex


The Tyrannosaurus rex is certainly the most widely known dinosaur in dinosaur history. It was first identified in 1905 by Henry F. Osborn and for almost a century it was the largest carnivore ever discovered. This continued until the discovery of the Spinosaurus and Giganotosaurus in the 1990's. At first it was considered as a carnivore, which carried itself upright, much as a human does, with the tail dragging behind it. The first complete Tyrannosaurus skeleton was unveiled in 1915 as standing upright. However, in the 1970's it was determined that such a posture would have caused serious strains on certain areas of the giant's body. It was then determined that the Tyrannosaurus walked horizontally with the tail held erect to balance the massive head.

Tyrannosaurus Teath
Tyrannosaurus rex teath.


Tyrannosaurus Track
Tyrannosaurus rex track.
The Tyrannosaurus, although it is no longer the largest carnivore known, it was the largest of its time and region. The Spinosaurus and Giganotosaurus are examples of more recently discovered dinosaurs that are larger than the Tyrannosaurus. Its tail was long and thick to balance the head. The legs were exceptionally strong and thick. The most distinguishing feature is the giant head, which is large enough to bite a small human whole. The teeth were on average, 8-16 cm long. The longest known tooth is 12 in long (1ft) making it the longest carnivore tooth ever discovered. It had small eyes and a narrow snout to provide unique binocular eye vision. It had tiny arms with two clawed fingers. The upper jaw was U shaped which is distinct among theropods, most having a V shaped jaw. This allowed the Tyrannosaurus to increase the amount of food he could hold in a bite. Its ears were similar to modern crocodiles, which have excellent hearing.


One of the longest ongoing debates among paleontologists tries to determine whether the Tyrannosaurus was an active predator or a scavenger. While its large head, long teeth, contribute to the idea that it was not just a scavenger, there are many evidences that it may have been. Its legs are thick and strong for traveling long distances as a scavenger would and also has small eyes and hands, and large olfactory lobes. It may have performed both functions as a predator and scavenger. The arms may have had several functions. The arms had many locations for muscle attachment making them extremely strong despite their size. They may have been used for lifting itself, for mating, or for holding struggling prey.

Popular Culture

The Tyrannosaurus rex is the most popular dinosaur to appear in modern culture. Its success may be due partially to the New York Times which stated in 1905 that the Tyrannosaurus was "the most formidable fighting animal of which there is any record whatever," the "king of all kings in the domain of animal life," and other such statements. It has made appearances in countless film and television productions the most influential being 1933's King Kong and Steven Spielberg's Jurassic Park and The Lost World.

ScienceViews Writer: Jason Hamilton.

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