To compensate for the immense bulk of the animal, many bones throughout the skeleton were hollow, reducing its weight without significant loss of strength.
Large fenestrae (openings) in the skull reduced weight and provided areas for muscle attachment, as in all carnivorous theropods.
and among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction.
Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail.
Tyrannosaurus had a much wider range than other tyrannosaurids.
Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous Period, 68 to 66 million years ago.
Tyrannosaurus rex was one of the largest land carnivores of all time; the largest complete specimen, located at the Field Museum of Natural History under the name FMNH PR2081 and nicknamed Sue, measured 12.3 meters (40 ft) long, Hutchinson et al.By far the largest carnivore in its environment, Tyrannosaurus rex was most likely an apex predator, preying upon hadrosaurs, armoured herbivores like ceratopsians and ankylosaurs, and possibly sauropods.Some experts have suggested the dinosaur was primarily a scavenger.Its taxonomy is also controversial, as some scientists consider Tarbosaurus bataar from Asia to be a second Tyrannosaurus species while others maintain Tarbosaurus is a separate genus.Several other genera of North American tyrannosaurids have also been synonymized with Tyrannosaurus.(2011) found that the maximum weight of Sue, the largest complete Tyrannosaurus specimen, was between 9.5 and 18.5 metric tons (9.3–18.2 long tons; 10.5–20.4 short tons), though the authors stated that their upper and lower estimates were based on models with wide error bars and that they "consider [them] to be too skinny, too fat, or too disproportionate" and provided a mean estimate at 14 metric tons (15.4 short tons) for this specimen. (2009) tested dinosaur mass estimation procedures on elephants and concluded that those of dinosaurs are flawed and produce over-estimations; thus, the weight of Tyrannosaurus, as well as other dinosaurs, could have been much less.