T. rex balanced a huge skull on tiny, strong arms
Tyrannosaurus rex—Latin rex for king—is among the best-represented large theropods, a bipedal carnivore whose massive skull rode opposite a heavy tail. Hind limbs dwarfed short yet powerfully built forelimbs. Nearly complete skeletons, and even reported soft tissue in at least one specimen, fuel museums and research alike.
Tyrannosaurus roamed Laramidia, then an island continent covering today's western North America, between roughly 69 and 66 million years ago, making it one of the last non-avian dinosaurs before the Cretaceous–Paleogene extinction. Its two-fingered arms were short beside the massive hind legs yet strong for their size. Most modern estimates allow for animals over 13 m long, about 4 m tall at the hip and around 8.8 tonnes, with the strongest estimated bite of any land animal. The long argument over whether it hunted or merely scavenged has largely closed: most paleontologists now treat it as an apex predator of hadrosaurs and young horned and armoured dinosaurs.
Its discovery was piecemeal. A tooth turned up in July 1874 on South Table Mountain near Golden, Colorado, and in 1892 Edward Drinker Cope named two vertebra fragments Manospondylus gigas, taking them for a horned dinosaur. Barnum Brown dug the first partial skeleton in Wyoming in 1900 and a second in Montana's Hell Creek beds in 1902. Henry Fairfield Osborn named it in 1905, pairing Greek words for "tyrant lizard" with Latin rex, "king." That type specimen later went to Pittsburgh's Carnegie Museum for $7,000 in 1941.
Brown's bones were the only known specimens until the 1960s, when renewed digging produced 42 skeletons. The most famous, Sue, about 85% complete, was found in Hell Creek on 12 August 1990; after a court fight over ownership, the Field Museum paid $7.6 million for it. Bone study shows Sue reached adult size at 19 and died at 28. Stan, with 199 bones, sold for $31.8 million in 2020 and bears healed breaks and a tooth-sized hole in its skull.
Fresh finds keep refining the picture. Bucky, found in 1998 by a 20-year-old, preserved the first T. rex wishbone. Soft tissue and proteins have been reported from at least one skeleton, and the boundaries of the genus stay contested, with Asia's Tarbosaurus sometimes folded in and proposed species such as T. mcraeensis disputed.
Source: Tyrannosaurus
