AverostraAvetheropodaCoelurosauriaDinosauriaEusaurischiaEutyrannosauriaLate CretaceousNeotheropodaNorth AmericaOrionidesPantyrannosauriaSaurischiaTetanuraeTheropodaTyrannoraptoraTyrannosauridaeTyrannosaurinaeTyrannosauroidea

Tyrannosaurus rex

Dinosaur: Tyrannosaurus rex

Cretaceous: 72.7–66 Ma
Type: Theropod

Length*:12.6 m41.3 ft
Weight*:11 tons24,251 lb
Speed:23 km/h14 mph
ESR: 4 / 4 (estimated size reliability)
*The largest known specimen



Description

Tyrannosaurus rex

Tyrannosaurus rex, often known simply as T. rex, is perhaps the most famous and iconic dinosaur. This massive carnivore lived approximately 72.7 to 66 million years ago during the Late Cretaceous period, just before the mass extinction that ended the age of the dinosaurs. The name Tyrannosaurus rex means “tyrant lizard king,” reflecting its status as one of the largest and most formidable predators of its time. Fossils of T. rex have been found primarily in North America, particularly in the Hell Creek and Lance Formations.

Physical Characteristics

Tyrannosaurus rex was a giant theropod dinosaur, reaching up to 12–13 meters (39–43 feet) in length and standing about 4 meters (13 feet) tall at the hips. The estimated weight of an adult T. rex ranges from 8 to 14 metric tons. It had a massive skull, measuring up to 1.5 meters (5 feet) in length, with large, robust jaws equipped with around 60 thick, serrated teeth, some of which were up to 30 cm (12 inches) long. The powerful bite force of T. rex is estimated to have been between 35,000 to 57,000 Newtons (7,870 to 12,800 pounds-force), among the strongest of any known terrestrial animal. The dinosaur had short, muscular arms with two-fingered hands, which may have been used for grasping prey or aiding in getting up from a prone position. Its legs were long and strong, suggesting that T. rex was capable of moving relatively quickly for its size, with estimated speeds of up to 23 km/h (14 mph).

Diet and Feeding Habits

Tyrannosaurus rex was a carnivore at the top of the food chain, likely preying on a variety of large herbivorous dinosaurs, such as Triceratops and Edmontosaurus. Its powerful bite, combined with its serrated teeth, allowed it to crush bones and consume entire carcasses, including bones, which provided essential nutrients like calcium. Evidence from bite marks on fossil bones, as well as tooth wear patterns, suggests that T. rex was both an active predator and a scavenger, feeding opportunistically on carcasses. Recent studies also indicate that T. rex had an extremely keen sense of smell, vision, and hearing, which would have made it a highly effective hunter.

Habitat and Distribution

Tyrannosaurus rex lived in what is now North America, in environments ranging from coastal floodplains to forested regions and river valleys. The Hell Creek Formation, where many T. rex fossils have been found, was a warm, humid environment with a mixture of coniferous and deciduous trees, flowering plants, and diverse animal life. This habitat would have provided abundant food sources for a large predator like T. rex.

Behavior and Social Structure

The social behavior of Tyrannosaurus rex remains a subject of scientific debate. Some evidence, such as the discovery of multiple T. rex specimens in the same area, suggests the possibility of social or pack-like behavior, although other researchers argue that these gatherings could have been caused by environmental factors, such as waterholes attracting prey and predators alike. Injuries and pathologies on T. rex bones, including bite marks and healed fractures, suggest that these dinosaurs may have engaged in intraspecific combat, possibly over territory, mates, or food. There is also evidence that T. rex juveniles had different hunting strategies from adults, possibly filling different ecological niches to reduce competition within the species.

Discovery and Research

Tyrannosaurus rex was first discovered in 1902 by fossil hunter Barnum Brown and was later described and named by Henry Fairfield Osborn in 1905. The first complete skeleton was discovered in Montana, USA, and remains one of the most famous dinosaur discoveries in history. Since then, dozens of T. rex specimens have been found, including several nearly complete skeletons. The most famous of these is “Sue,” discovered in South Dakota in 1990, which is the largest and most complete T. rex skeleton ever found. Ongoing research on T. rex continues to reveal new insights about its growth, metabolism, sensory abilities, and behavior, making it one of the most studied dinosaurs.

Significance and Interesting Facts

Tyrannosaurus rex holds a significant place in both paleontology and popular culture as one of the largest and most fearsome predators to have ever lived. Recent studies have shown that T. rex grew rapidly during its teenage years, reaching its full size in about 20 years and potentially living up to 30 years. Research into its sensory capabilities suggests that it had binocular vision, which would have given it excellent depth perception, and an olfactory bulb that suggests a keen sense of smell, similar to modern birds of prey. Its role as a top predator in its ecosystem, combined with its distinctive anatomy and adaptations, makes T. rex an enduring symbol of prehistoric life.


Locations


Sources

Material: At least more than 60 individuals (include skulls and almost complete skeletons).
References: Paul GS, Persons WS, Van Raalte J (2022). "The Tyrant Lizard King, Queen and Emperor: Multiple Lines of Morphological and Stratigraphic Evidence Support Subtle Evolution and Probable Speciation Within the North American Genus Tyrannosaurus".
J. P. Hunter and D. A. Pearson. 1996. First record of Lancian (Late Cretaceous) mammals from the Hell Creek Formation of southwestern North Dakota, USA. Cretaceous Research

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