One cannot discuss dinosaur royalty without paying homage to Tyrannosaurus rex, often abbreviated as T. rex. This colossal carnivore not only ranks among the largest known dinosaurs but also stands as an emblem of prehistoric might and majesty. Immortalized in blockbuster films like the “Jurassic Park” series and prominently featured in exhibitions such as the revered showcase at the American Museum of Natural History in New York City, T. rex undeniably holds court as the undisputed king of the dinosaurs.

The very name “Tyrannosaurus rex” embodies its supremacy, translating to “king of the tyrant lizards” from Greek and Latin roots. Coined in 1905 by Henry Fairfield Osborn, then-president of the American Museum of Natural History, this moniker underscores T. rex’s dominance in the ancient ecosystem.

Belonging to the Tyrannosauroidea family, characterized by massive predatory dinosaurs sporting diminutive arms and two-fingered hands, T. rex shares its lineage with an array of formidable counterparts. These include Albertosaurus, Alectrosaurus, Alioramus, and others, each contributing to the tapestry of Tyrannosaurid diversity.

Fossils of T. rex predominantly emerge from the expanse of western North America, spanning from Alberta to Texas. However, recent studies suggest a tantalizing possibility: T. rex may have originated from Asia and migrated to North America around 67 million years ago. Skeletal analyses reveal striking similarities between T. rex and its Asian relatives, Tarbosaurus and Zhuchengtyrannus, fueling speculation about its transcontinental journey.

Yet, the debate over T. rex’s origins persists. While some scholars advocate for its North American evolution, others entertain the notion of an Asian ancestry. The narrative of Tyrannosaurus rex continues to evolve, enticing paleontologists and captivating the public imagination with its enigmatic legacy.

T. rex fossils reveal that the animals could grow to 40 feet (12.2 m) in length. (Image credit: Kirstin Brink)


The most comprehensive T. rex skeleton ever unearthed, affectionately dubbed Sue after its finder, paleontologist Sue Hendrickson, provides invaluable insight into the dimensions of this legendary predator. Sue’s measurements reveal T. rex’s imposing stature, standing up to 13 feet (4 meters) tall at the hips and stretching an impressive 40 feet (12.3 meters) in length. A meticulous analysis, featured in a 2011 publication in the journal PLOS ONE, estimates T. rex’s weight at a staggering 9 tons (approximately 8,160 kilograms).

However, in 2019, researchers unveiled a new contender for T. rex supremacy: “Scotty,” another fossil specimen that surpasses Sue in mass. With an estimated weight of 19,555 lbs. (8,870 kilograms), Scotty claims the title of the heaviest T. rex ever discovered. Notably, Scotty’s longevity sets it apart, enduring beyond the typical lifespan of its kin to reach an impressive 30 years of age, surpassing Sue’s tenure by two years.

T. rex boasted formidable features, with robust thighs and a muscular tail that facilitated agile movement, effectively counterbalancing its imposing head, exemplified by Sue’s colossal 5-foot-long skull. Insights from a 2011 study, which delved into T. rex’s muscle structure and center of gravity, propose that this behemoth could sprint at speeds ranging from 10 to 25 mph (17 to 40 km/h), aligning with earlier estimations.

Despite its massive frame, T. rex sported diminutive forearms, raising questions about their utility in hunting or feeding. Research by Michael Habib of the University of Southern California suggests that these puny appendages may have been a trade-off for the dinosaur’s powerful bite, with neck muscles taking precedence to support the weighty skull and enhance biting force. This adaptation likely conferred evolutionary advantages, as shorter arms minimized the risk of injury and conserved energy.

Central to T. rex’s predatory prowess was its formidable skull, equipped with the strongest bite force ever recorded in a terrestrial animal. As revealed by a 2012 study in Biology Letters, T. rex could exert a staggering bite force of up to 12,814 pounds-force (57,000 Newtons), rivaling the impact of a medium-sized elephant’s seated position. In the relentless pursuit of prey, T. rex relied on the sheer might of its jaws to secure its status as the apex predator of its era.

Artwork by Scott Hartman reveals the bone structure of T. rex. (Image credit: © Scott Hartman / All rights reserved)

T. rex possessed a formidable array of serrated teeth, with the largest tooth of any carnivorous dinosaur measuring a remarkable 12 inches (30 centimeters) in length. A 2012 study published in the Canadian Journal of Earth Sciences elucidated the diverse functions of these teeth: the front teeth for gripping and pulling, the side teeth for tearing flesh, and the back teeth for dicing meat and facilitating ingestion. Notably, T. rex’s teeth were broad and somewhat blunt, ensuring durability against the struggles of prey, as revealed by the study.

Despite its colossal size, T. rex’s lineage traces back to much smaller predecessors. The earliest tyrannosaurs, ranging from human to horse size, emerged approximately 170 million years ago during the mid-Jurassic period. Despite their diminutive stature, these early tyrannosaurs possessed advanced brains and sensory capabilities, including keen hearing, as detailed in a 2016 study in the journal Proceedings of the National Academy of Sciences. This discovery, exemplified by the mid-Cretaceous tyrannosaur Timurlengia euotica, suggests that the cognitive sophistication developed by smaller tyrannosaurs facilitated their ascent to apex predator status upon reaching the dimensions of T. rex.

Teenage T. rex were more lightly built and faster than the much larger, lumbering, bone-crushing adults they would grow into. (Image credit: Julius T. Csotonyi)


T. rex, a colossal carnivore, predominantly preyed upon herbivorous dinosaurs like Edmontosaurus and Triceratops. According to University of Kansas paleontologist David Burnham, this apex predator displayed a voracious appetite, rapidly consuming hundreds of pounds of flesh through scavenging and hunting.

While scavenging provided some sustenance, T. rex faced the relentless challenge of securing fresh kills to satiate its hunger. Circumstantial evidence initially supported the notion of T. rex as a hunter, including bite-marked bones, proximity of teeth to carcasses, and fossilized footprints indicative of pursuits. However, a groundbreaking 2013 study in the journal Proceedings of the National Academy of Sciences provided conclusive proof of T. rex’s predatory prowess: a T. rex tooth lodged within the tailbone of a duckbill dinosaur, indicating a failed attack.

Moreover, T. rex’s dietary preferences extended to its own kind, as revealed by a 2010 analysis in PLOS ONE documenting T. rex bones bearing deep gashes from T. rex teeth, hinting at cannibalistic tendencies. Nonetheless, the circumstances surrounding these encounters remain ambiguous.

The social dynamics of T. rex’s hunting behavior remain a subject of debate. In 2014, discoveries of dinosaur track marks in the Canadian Rockies suggested pack behavior among T. rex’s relatives, such as Albertosaurus, Gorgosaurus, or Daspletosaurus, as detailed in a study published in PLOS ONE. Despite these intriguing findings, the solitary or communal hunting habits of T. rex itself continue to elude definitive conclusion.


T. rex thrived during the Maastrichtian age of the upper Cretaceous period, spanning from 67 million to 65 million years ago, marking the twilight of the Mesozoic Era. As one of the final non-avian dinosaurs before the catastrophic Cretaceous-Paleogene extinction event, T. rex left an indelible mark on prehistoric history.

This formidable predator roamed the expanse of western North America, a region then characterized as the island continent of Laramidia. Over 50 T. rex skeletons have been discovered, some remarkably well-preserved with traces of soft tissue and proteins, as documented by National Geographic.

The first partial skeleton of T. rex was unearthed by fossil hunter Barnum Brown in Montana’s Hell Creek Formation in 1902, later showcased at the Carnegie Museum of Natural History in Pittsburgh. Additional discoveries, including specimens showcased in the American Museum of Natural History in New York, underscore T. rex’s enduring legacy.

In 2007, scientists reported a potential T. rex footprint discovery in Hell Creek, documented in the journal Palaios. If confirmed, this would mark only the second verified T. rex footprint ever found, complementing the initial discovery in New Mexico in 1993.

Contributions from Kim Ann Zimmermann and Live Science senior writer Laura Geggel enhance the understanding of T. rex’s ancient habitat, with ongoing updates ensuring the continual exploration of this iconic dinosaur’s story, as evidenced by the work of Live Science Reference Editor Vicky Stein.

Learn about T. rex’s massive teeth, bones, habitat and other dinosaur secrets. (Image credit: Ross Toro, Livescience contributor)

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