illions of years after its lifetime, Tyrannosaurus rex has become a legend, but just over a century ago nobody even realised such a creature ever walked the Earth. About the size of a double-decker bus, with a bite eight times greater than a lion's, a T-rex, if alive today, could easily swallow an adult human whole. Fortunately for us, it became extinct before humans ever evolved.
Although dinosaurs had been known about since the 1820s, as palaeontologists extracted fossils from age-old rock around the world, it wasn't until 1905 that this most fearsome beast was officially identified.
T-rex was the largest of the tyrannosaurs, a group of flesh-eating reptiles which inhabited forest and swampland in what is now North America. They were also one of the last dinosaur species to exist, during the final stages of the Cretaceous period, just before the great extinction some 65 million years ago.
The story of the discovery, excavation and identification of T-rex is complex and took place during a period of intense competition between the American Museum of Natural History in New York and the Carnegie Museum in Pittsburgh, which each wanted to be first to publish the authoritative account of life during the Cretaceous period. The first significant finds - a fossilised jaw and section of neck vertebrae - were made in 1900 by American Museum palaeontologist, Barnum Brown.
The specimens were recovered from a bank of clay near Seven Mile Creek, a few miles from the Cheyenne river in the western state of Wyoming. Brown's superior, curator Henry Fairfield Osborn, confirmed these fossils belonged to a new species and he identified them at first as Dynamosaurus imperiosus. In the next few years, Brown made further discoveries of leg and skull pieces in Hell Creek, Montana. Having examined these, Osborn wrote to Brown in 1905: "I have just described the big dinosaur under the name Tyran(n)osaurus rex."
He was using the convention of creating a new Latin name, based on mostly Greek words, in this instance "tyrant lizard king". A peculiarly small humerus (arm bone) had also been found at Hell Creek. "I hardly believed it possible that the humerus you have found belongs to this animal. It will upset absolutely all that is known of the osteology of these carnivorous animals."
Osborn quickly accepted this bone was indeed part of the T-rex; he also realised that Brown's 1900 jaw and neck specimens belonged to this new species, and he renamed them accordingly. Barnum Brown's most successful find came in 1908. One day on his way back to camp, he spotted four weathered tail vertebrae protruding from a sandstone hillside and was excited to see they belonged to another T-rex skeleton. Using a plough, then dynamite, he gradually exposed more vertebrae, a pelvis, a set of articulated ribs and, finally, a complete skull.
All his findings were crated up and sent across country to New York, where painstaking preservation and analysis were undertaken, lasting several years, before a virtually complete skeleton could be mounted. The first T-rex went on public display in the American Museum in 1915, where it still stands today. Perhaps surprisingly, since these early discoveries fewer than 30 fossilised T-rex skeletons have surfaced, predominantly in North America, including a close relative in Mongolia sometimes called the Tarbosaurus, thought by many palaeontologists to belong to the Tyrannosaurus family. Our knowledge changes all the time as new evidence is uncovered. Until 10 years ago, T-rex was established as the biggest carnivorous dinosaur, then a creature two tonnes heavier was identified in South America - the Giganotosaurus. It is possible that a larger T-rex specimen will surface one day, allowing the species to regain its lead position.
In the 100 years since its discovery, T-rex has been the subject of thorough study. Reconstructions indicate that an average adult weighed about seven tonnes, stood up to 4m tall and was 12m long, making it able to make eye-contact with passengers on the top deck of a double-decker bus.
Its tail was stiff and pointed and probably served to counterbalance the enormous head, aid agility and negotiate swift turns. It has been established that T-rex was a meat-eater living in a warm forested habitat alongside the three-horned Triceratops and duckbilled Hadrosaurs, on which it no doubt fed; some skeletal remains of these herbivores clearly bear the imprint of T-rex teeth. The jaws contained 50 to 60 dagger-like teeth which were replaced when broken and had tiny serrated edges. They could slice through meat like a steak knife. Yet experts remain divided on whether T-rex was a flesh-tearing predator or a bone-crunching scavenger of carcasses. One argument is that its small eyes and feeble arms which did not reach its mouth, would have been ineffectual for hunting live prey. It is also thought to have been a slow lumbering creature at 10mph, which many potential victims could outrun.
Analysis of the skull, however, has revealed that T-rex possessed an extremely powerful sense of smell. The olfactory bulb in its brain was huge. A human's is the size of a pea, whereas T-rex's bulb was the size of an orange. Further proof of the creature's diet arose in 1998 when a huge coprolite (fossilised faeces) was excavated in Canada. Palaeontologists from the Royal Saskatchewan Museum discovered that the whitish-green rock (44cm x 15cm x 13cm) contained semi-digested bone fragments, perhaps from the head frill of a Triceratops. This is the only example of T-rex dung that has ever been found. Another unique find, by American geologist Chuck Pillmore, was a T-rex footprint in an undisclosed location in the state of New Mexico. Fossilised skin is extremely rare but small specimens from T-rex have been found, described as rough, scaly and pebbled like an alligator's. Scientists believe that all dinosaurs had tough flexible skin protected by bony plates embedded in the surface, but there is nothing to indicate the original colour when living. Probably, they developed camouflage like modern animals to increase the chances of survival. Experts at the Carnegie Museum in Pittsburgh are preparing a T-rex called Samson, whose skull may be the finest ever collected since it appears to have survived fossilisation complete and without any distortion. But a complete T-rex skeleton has yet to be unearthed, so no one can say exactly how many bones they had. A 70 per cent intact fossil of a young T-rex was found recently in South Dakota. Given the nickname Tinker, it was five-years-old when it died, nearly 6m long and may have weighed 1,200 pounds, about two-thirds the size of its parents.
Fictional renditions of the T-rex have always been popular, from the nightmarish creations of Steven Spielberg to the cuddly, purple children's favourite, Barney. Arthur Conan Doyle did not include them in The Lost World (1912), his seminal man-meets-dinosaurs adventure story, although many subsequent film and TV adaptations felt free to shoehorn the creatures in. In 1933, King Kong fended off a hostile T-rex - a match made in movie heaven, soon to be restaged in a remake by Peter Jackson, the director of The Lord of the Rings. In Jurassic Park (both Michael Crichton's book and Spielberg's 1993 film adaptation), a scientist and his family come under attack when a power cut deactivates barriers around a tyrannosaur paddock.
The special effects were startlingly convincing, and what dinosaur movie would feel complete without a star turn from a ferocious T-rex?
The fact that, strictly speaking, T-rex was not from the Jurassic period seemed not to deter the storytellers; its Cretaceous contemporaries, Triceratops and Velociraptor, were allowed to make similar anachronistic appearances. The Natural History Museum in London has long been a must-see for anyone interested in prehistoric life. The Central Hall famously displays a gigantic plastercast of a Diplodocus skeleton, first unveiled in 1905. A small exhibition on the landing above acknowledges the centenary.
Around the hall are casts and fossils of other extinct creatures, including a dolphin-like Ophthalmosaurus found in Oxford clay. Visitors can also admire Britain's only complete mammoth skull (with tusks) dug from the River Roding near Ilford in 1864. Mammoths lived in relatively recent times and are not dinosaurs. Gallery 21 is devoted to the extensive dinosaur exhibition with full-size skeleton casts of a Triceratops, Iguanodon and Stegosaurus. Also on display is an arm section from an Edmontosaurus clearly showing preserved skin folds and wrinkles. The star attraction here, though, is a lifelike animatronic reconstruction of T-rex. An improvement on an earlier model, this one apparently uses its senses to spot prey (including museum visitors) and is therefore kept in a constant state of frenzy by passing school parties. It's the centrepiece of a mini-exhibition detailing all that we now know about the T-rex, together with the actual jaw and dagger-like teeth discovered by Barnum Brown in Wyoming way back in 1900.
Meet the relatives
Megalosaurus (great lizard)
Period: Jurassic (164-160 mya - million years ago) Fossils: England and northern Europe, Asia, Argentina Measurements: 3m x 9-10m
Allosaurus (different lizard)
Period: Late Jurassic (155-145 mya) Fossils: US, Portugal, Tanzania, Australia Measurements: 5m x 12m
Tyrannosaurus (tyrant lizard)
Period: Late Cretaceous (85-65mya) Fossils: North America, Mongolia Measurements: 4-6 x 12m
Velociraptor (fast thief)
Period: Late Cretaceous Fossils: Mongolia, Russia, China Measurements: 1m x 1.5-2m
Iguanodon (iguana tooth) Period: Early Cretaceous (135-125mya) Fossils: England, Belgium, Germany, Africa, US Measurements: 3m x 6-10m
Diplodocus (double beam)
Period: Late Jurassic Fossils: US Measurements: 4m x 27m
Stegosaurus (plated lizard)
Period: Late Jurassic Fossils: US, Europe, China Measurements: 3m x 12m
Triceratops (three-horned face)
Period: Late Cretaceous Fossils: North America Measurements: 2m x 9m
Although not every fledgling palaeontologist will find the remains of dinosaurs, it is relatively easy and rewarding to find fossils of smaller early lifeforms such as ammonites and echinoids.
The coastlines of Sussex and Dorset (especially at Lyme Regis) are famous for yielding relics from the Jurassic period. The Charmouth Heritage Coast Centre organises fossil walks throughout the summer. There are also good sites in Yorkshire (the cliffs at Port Mulgrave and Kettleness) and at quarries in the central counties.
Ardley Quarry in Oxfordshire recently revealed hundreds of dinosaur footprints preserved in a layer of limestone. These tracks were made 168 million years ago by creatures such as the Megalosaurus, providing incontrovertible evidence at last that the large theropods could indeed run. Permission is required before visiting this site.
Dinosaurs lived between 230 and 65 million years ago during the Mesozoic Era, which is itself subdivided in to three long periods of time: Triassic, Jurassic and Cretaceous. The term "dinosauri" (meaning "terrible lizards") was coined in 1842 by Richard Owen, the Victorian scientist who originally conceived the Natural History Museum.
Dinosaurs are classified into groups according to their hip design: the bird hipped ornithischians and lizard-hipped saurischians. The latter are subdivided into theropods (two-legged carnivores) and sauropods (four-legged herbivores).
Dinosaurs were entirely land-based; the flying animals of the time were pterosaurs, while aquatic creatures were ichthyosaurs, pliosaurs or plesiosaurs. Dinosaurs became extinct at the end of the Mesozoic Era and the cause is still debated, but global catastrophe is a popular theory, perhaps a meteor strike in Mexico or a volcanic eruption in India.
* Fossil-hunting websites: www.discoveringfossils.co.uklocations.htm