EXHIBIT 01
Tyrannosaurus rex
Bone-crushing jaws left traces of meals in the fossil record.
TWO WAYS TO PICTURE THE PAST
Compare the evidence with the familiar movie image. The illustrations are not to a shared scale.
A reconstruction based on the skeleton of “Black Beauty,” with a deep skull, short arms and a long tail. The open mouth shows teeth. A 2023 study supports lip-like tissues covering theropod teeth when the mouth closed; these tissues are inferred. Another T. rex specimen, Wyrex, preserves scales on parts of the neck, pelvis and tail. Color and the complete skin covering remain uncertain. [1] [8] [9]
Life reconstruction of Tyrannosaurus rex specimen TMP 1981.006.0001 ("Black Beauty") — Connor Ashbridge. CC BY 4.0. Resized and converted to WebP; complete composition retained.
An Original interpretation of the screen-style predator, with rugged skin, prominent ridges and exposed teeth. A 2023 study supports lip-like tissues covering theropod teeth when the mouth closed, but the soft tissues are inferred. The detailed texture, colors, setting and pose are artistic choices. [8] [9]
Original artwork · artistic interpretation.
Scientific view: credited paleoart interpreting fossil evidence. Movie-style view: Original artwork. Colors and many soft tissues are uncertain.
MEET THE ANIMAL
Tyrannosaurus rex lived near the end of the Cretaceous Period in western North America. Fossils from the United States and Canada reveal a large animal that moved on two legs. Its huge skull and strong teeth give it a very different outline from the small arms beneath its shoulders. Those arms are familiar, but their exact jobs remain uncertain. [S1]
Tyrannosaurus was equipped for powerful feeding. Strong jaws and large teeth could tear flesh and crush bone, supporting its role as a meat eater. The museum account also allows scavenging an animal that was already dead. Feeding capability does not establish how every meal was obtained: an animal can hunt and scavenge, and an imposing jaw alone does not preserve the details of a particular kill. [S1]
One individual provides an especially unusual clue about reproduction. Researchers identified bone tissue associated with producing eggs in the specimen called MOR 1125. This gives us information about that animal, rather than a complete picture of every Tyrannosaurus. It does not reveal the number of eggs in a nest or how parents cared for young. Fossils can answer a narrow question while leaving much of an animal's life open. [D3]
PREHISTORIC ANIMAL DOSSIER
The animal, the evidence, and the questions still open.
Tyrannosaurus rex was a large predator from the closing Cretaceous of western North America. Its teeth and feeding traces support bone consumption; reproductive tissue offers a rare window into an individual's biology.
Profile scope: Species — Tyrannosaurus rex
Source supported identifies a description documented by the cited source. Inferred marks a reconstruction or functional estimate. Debated marks competing interpretations. Not established means the sources reviewed for this dossier do not support a firm conclusion; it does not mean a behavior never occurred.
A size reference is an estimate, not a population range. Nesting evidence does not by itself establish courtship, mate choice, or lifelong pairing.
About 12–13 m (museum reference)
The museum gives about 12 m, with large specimens nearing 13 m. These are reconstruction references rather than a complete growth or population range; maturity is not assessed for each estimate. [D1]
About 7 tonnes (museum reference)
The museum's rounded reference is 7,000 kg; larger specimens receive estimates above 8,000 kg. Fossil body mass requires reconstruction rather than weighing. [D1]
Meat; hunting and scavenging
Teeth, bite marks on herbivores and bone fragments in attributed dung support meat and bone consumption. Feeding marks alone do not identify a kill. [D1]
Western North America
Fossils occur in Montana, South Dakota and Alberta. This establishes regional occurrence rather than a single preferred microhabitat. [D2]
Two-legged terrestrial movement
Its hindlimbs supported a bipedal animal. Published maximum-speed estimates depend on biomechanical assumptions. [D1]
Large skull, strong teeth, small arms
Its large skull and bone-crushing teeth contrast with short forelimbs. The forelimbs' precise functions remain uncertain. [D1]
Egg production supported in MOR 1125
Chemical and histological tests identify medullary tissue associated with egg production in this individual. This does not reveal clutch size, nests or parental care. [D3]
Not established here
Reviewed sources do not establish a T. rex courtship sequence or mating posture.
Biting interactions; pack hunting unconfirmed
Marks on tyrannosaur bones document interactions involving bites. Their motives and coordinated hunting are unresolved. [D1]
Sources and inspection notes for the claims in this profile.
THE STORY IN THE FOSSILS
Tyrannosaurus rex lived about 68–66 million years ago. Its fossils come from western North America, including Montana and South Dakota in the United States and Alberta in Canada. The Natural History Museum gives about 12 metres as a reference length and describes large specimens such as Sue and Scotty as nearly 13 metres long. [3] [1] [2]
Its jaws and teeth could break bone. Bite marks attributed to Tyrannosaurus occur on Triceratops and Edmontosaurus fossils, providing evidence of feeding. A bite mark alone does not tell us whether the animal was killed or scavenged. The Natural History Museum describes T. rex as both a hunter and a scavenger. [7] [2]
Barnum Brown recovered the partial skeleton that became the species' name-bearing specimen in Montana's Hell Creek Formation in 1902. Henry Fairfield Osborn named Tyrannosaurus rex in 1905. Even this familiar dinosaur is reconstructed from incomplete evidence: many recovered skeletons lack substantial parts. [1]
Approximate museum reference for adult-sized T. rex, including large known specimens; total body length, not height. This published 12–13 m reference is not a complete biological size range or a population confidence interval. The cited dates are approximately 68–66 million years ago. Unknown does not mean zero.
About 7,000 kg: the Australian Museum's T. rex reference estimate at the same educational scope as its 12–13 m length. A single rounded estimate, not a fixed mass or species-wide mass interval. Life stage and estimation method are not specified by the museum. [4]
Sources and evidence notes for this exhibit.
KEEP EXPLORING
Triceratops horridus
Three horns, a broad frill, and a plant-eater beneath the formidable silhouette.
Stegosaurus stenops
A small head, a skyline of plates, and four spikes at the tail.
Brachiosaurus altithorax
Air-filled ribs, towering shoulders, and a fossil record with big gaps.
