Tyrannosaurus rex

Tyrannosaurus was a large theropod dinosaur from the late Cretaceous period. It is probably the most famous dinosaur.

Facts
Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to the large and powerful hindlimbs, Tyrannosaurus forelimbs were small, though unusually powerful for their size, and bore two clawed digits. Although other theropods rivaled or exceeded Tyrannosaurus rex in size, it was the largest known tyrannosaurid and one of the largest known land predators, the most complete specimen measuring up to 12.3 metres in length, up to 4 metres tall at the hips, and up to 6.8 metric tons in weight. By far the largest carnivore in its environment, Tyrannosaurus rex may have been an apex predator, preying upon hadrosaurs, ceratopsians, and possibly sauropods, although some experts have suggested it was primarily a scavenger. The debate over Tyrannosaurus as apex predator or scavenger is among the longest running in paleontology.

More than 30 specimens of Tyrannosaurus rex have been identified, some of which are nearly complete skeletons. Soft tissue and proteins have been reported in at least one of these specimens. The abundance of fossil material has allowed significant research into many aspects of its biology, including life history and biomechanics. The feeding habits, physiology and potential speed of Tyrannosaurus rex are a few subjects of debate. Its taxonomy is also controversial, with some scientists considering Tarbosaurus bataar from Asia to represent a second species of Tyrannosaurus and others maintaining Tarbosaurus as a separate genus. Several other genera of North American tyrannosaurids have also been synonymized with Tyrannosaurus.

Description
Tyrannosaurus rex was one of the largest land carnivores of all time; the largest complete specimen, FMNH PR2081 ("Sue") measured 12.3 metres long, and was 4 metres tall at the hips. Mass estimates have varied widely over the years, from more than 7.2 metric tons, to less than 4.5 metric tons, with most modern estimates ranging between 5.4 and 6.8 metric tons. Packard et al. (2009) tested dinosaur mass estimation procedures on elephants and concluded that dinosaur estimations are flawed and produce over-estimations; thus, the weight of Tyrannosaurus could be much less than usually estimated. Other estimations have concluded that the largest known Tyrannosaurus specimens had masses approaching or exceeding 9 tonnes. The neck of Tyrannosaurus rex formed a natural S-shaped curve like that of other theropods, but was short and muscular to support the massive head. The forelimbs had only two clawed fingers, along with an additional small metacarpal representing the remnant of a third digit. In contrast the hind limbs were among the longest in proportion to body size of any theropod. The tail was heavy and long, sometimes containing over forty vertebrae, in order to balance the massive head and torso. To compensate for the immense bulk of the animal, many bones throughout the skeleton were hollow, reducing its weight without significant loss of strength.

The largest known Tyrannosaurus rex skulls measure up to 5ft in length. Large fenestrae (openings) in the skull reduced weight and provided areas for muscle attachment, as in all carnivorous theropods. But in other respects Tyrannosaurus '  skull was significantly different from those of large non-tyrannosauroid theropods. It was extremely wide at the rear but had a narrow snout, allowing unusually good binocular vision. The skull bones were massive and the nasals and some other bones were fused, preventing movement between them; but many were pneumatized (contained a "honeycomb" of tiny air spaces) which may have made the bones more flexible as well as lighter. These and other skull-strengthening features are part of the tyrannosaurid trend towards an increasingly powerful bite, which easily surpassed that of all non-tyrannosaurids. The tip of the upper jaw was U-shaped (most non-tyrannosauroid carnivores had V-shaped upper jaws), which increased the amount of tissue and bone a tyrannosaur could rip out with one bite, although it also increased the stresses on the front teeth. A 2012 study performed by scientists Karl Bates and Peter Falkingham of the University of Liverpool suggested that the bite force of Tyrannosaurus could have been the strongest bite force of any terrestrial animal that has ever lived. The calculations suggested that adult T. rex could have generated from 35000 to 57000 Newtons of force in the back teeth, or the equivalent of three times the force estimated for a great white shark, 15 times the force of an African lion, 3 and a half times the force of an Australian saltwater crocodile and around 7 times the estimated force for Allosaurus. However, even higher estimates were made by professor Mason B. Meers of the University of Tampa in 2003. In his study, Meers estimated a possible bite force of around 183000 to 235000 Newtons or 18.3 to 23.5 metric tons; a bite force equivalent to that of the largest Megalodon shark specimens.

The teeth of Tyrannosaurus rex displayed marked heterodonty (differences in shape). The premaxillary teeth at the front of the upper jaw were closely packed, D-shaped in cross-section, had reinforcing ridges on the rear surface, were incisiform (their tips were chisel-like blades) and curved backwards. The D-shaped cross-section, reinforcing ridges and backwards curve reduced the risk that the teeth would snap when Tyrannosaurus bit and pulled. The remaining teeth were robust, like "lethal bananas" rather than daggers; more widely spaced and also had reinforcing ridges. Those in the upper jaw were larger than those in all but the rear of the lower jaw. The largest found so far is estimated to have been 30 centimetres long including the root when the animal was alive, making it the largest tooth of any carnivorous dinosaur yet found.

Death of a Dynasty
A female Tyrannosaurus has failed to have a healthy clutch of eggs (The babies inside them have been choked by volcanic ash). She almost immediately comes back into season. Her mating call is heard by a male Tyrannosaurus, who kills a Triceratops to attract her. It works, and they mate. After this, the female chases the male out of her territory. She later lays twelve eggs, protecting them from Didelphodons and Dromeosaurs. She does not eat during this period. Only three eggs manage to hatch. She later kills an Anatotitan (by injuring the flanks and crushing the neck vertebrae) and brings back a piece of Anatotitan meat for her hatchlings, were two picks on a third one. These two hatchlings kill the third hatchling during the night. Meanwhile, an Ankylosaurus severely injures the mother by smacking its tail club into her hip, breaking her femur, and rupturing some of her internal organs. The sister limps away in agony. She later dies. The next day, the asteroid crashes into the earth.

The Most Deadliest Sea
Tyrannosaurus made a large cameo roaring at the sea.

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