Overview Allosaurus is a genus of theropod dinosaur that lived 155 to 143 million years ago during the late Jurassic period. The first fossil remains that could definitively be ascribed to this genus were described in 1877 by Othniel C. Marsh. The name "Allosaurus" means "different lizard", alluding to its lightweight vertebrae, which Marsh believed were unique. The genus has a very complicated taxonomy and includes at least three valid species, the best known of which is A. fragilis. The bulk of Allosaurus remains come from North America's Morrison Formation, with material also known from the Alcobaça, Bombarral, and Lourinhã formations in Portugal. It was known for over half of the 20th century as Antrodemus, but a study of the abundant remains from the Cleveland-Lloyd Dinosaur Quarry returned the name "Allosaurus" to prominence. As one of the first well-known theropod dinosaurs, it has long attracted attention outside of paleontological circles.
Source: Wikipedia
Why it matters Dozens of individuals at the Cleveland-Lloyd quarry in Utah make it the best-known large Jurassic theropod. 'Big Al', a near-complete juvenile, shows 19 injuries including infected toe bones. Its skull was light and its jaws could gape unusually wide, suggesting it struck like an axe. Classification & discovery
Group Dinosaur · Theropod · NO_FAMILY_SPECIFIED
Parent taxon Allosauroidea
Diet carnivore
Environment terrestrial
Life habit ground-dwelling, solitary
Named by Marsh in 1877 When it lived 161.5 – 137.1 million years ago · Oxfordian to Berriasian · Jurassic, Cretaceous
Permian Triassic Jurassic Cretaceous Paleogene 60 80 100 120 140 160 180 200 220 240 260 280 300 End-Cretaceous extinction, 66 Ma Dimetrodon: 298.9–266.9 Ma · A sail-backed predator that is closer to mammals than to any dinosaur Dimetrodon Herrerasaurus: 237–227.3 Ma · An early predator from the dawn of the dinosaurs, named after the goat herder who found it Herrerasaurus Eoraptor: 233.6–227.3 Ma · One of the very first dinosaurs, a dog-sized omnivore from 231 million years ago Eoraptor Coelophysis: 227.3–192.9 Ma · A slender Triassic predator found by the hundreds at Ghost Ranch Coelophysis Plateosaurus: 227.3–199.5 Ma · The first big plant-eater: a two-legged Triassic forerunner of the sauropods Plateosaurus Megalosaurus: 205.7–66 Ma · The first dinosaur ever named, in 1824, decades before the word 'dinosaur' existed Megalosaurus Plesiosaurus: 205.7–66 Ma · The long-necked sea reptile Mary Anning found, often mistaken for a dinosaur Plesiosaurus Dilophosaurus: 201.4–184.2 Ma · A seven-metre Early Jurassic predator with twin head crests, and no venom or neck frill Dilophosaurus Heterodontosaurus: 201.4–184.2 Ma · A fox-sized dinosaur with tusks, incisors and cheek teeth all in one mouth Heterodontosaurus Cryolophosaurus: 199.5–184.2 Ma · The first dinosaur named from Antarctica, with a pompadour-like crest Cryolophosaurus Mamenchisaurus: 168.2–113.2 Ma · The longest neck of any animal: up to 15 metres, half of its body Mamenchisaurus Kulindadromeus: 168.2–165.3 Ma · A plant-eater with feather-like fuzz, suggesting all dinosaurs could grow feathers Kulindadromeus Anchiornis: 168.2–152.2 Ma · The first dinosaur with its whole colour pattern reconstructed Anchiornis Yi: 165.3–154.8 Ma · A pigeon-sized dinosaur with bat-like membrane wings Yi Stegosaurus: 161.5–93.9 Ma · Plates on its back, spikes on its tail and a famously small head Stegosaurus Allosaurus: 161.5–137.1 Ma · The top predator of the Jurassic plains of North America Allosaurus Brachiosaurus: 157.9–143.1 Ma · The giraffe of the dinosaur world, with front legs longer than its hind legs Brachiosaurus Diplodocus: 157.9–143.1 Ma · A 26-metre whip-tailed giant known from some of the most complete sauropod skeletons Diplodocus Apatosaurus: 157.9–143.1 Ma · A stockier cousin of Diplodocus with an extraordinarily thick neck Apatosaurus Brontosaurus: 154.8–143.1 Ma · The dinosaur that was declared a mistake in 1903 and resurrected in 2015 Brontosaurus Iguanodon: 154.8–66 Ma · The second dinosaur ever named, whose thumb spike was first mistaken for a nose horn Iguanodon Compsognathus: 154.8–145.1 Ma · A chicken-sized hunter and the first dinosaur known from a complete skeleton Compsognathus Supersaurus: 154.8–143.1 Ma · Possibly the longest dinosaur known from reasonably complete remains Supersaurus Europasaurus: 152.2–149.2 Ma · A sauropod shrunk to the size of a cow by life on a small island Europasaurus Archaeopteryx: 149.2–121.4 Ma · The feathered 'first bird' that tied birds to dinosaurs two years after Darwin's Origin Archaeopteryx Maraapunisaurus: 149.2–143.1 Ma · The lost vertebra that may have belonged to the largest dinosaur of all Maraapunisaurus Deinonychus: 143.1–93.9 Ma · The claw that launched the Dinosaur Renaissance Deinonychus Carcharodontosaurus: 143.1–72.2 Ma · An African giant with serrated, shark-like teeth, rediscovered after its bones were bombed Carcharodontosaurus Baryonyx: 139.1–110.1 Ma · A crocodile-snouted fish-eater found by an amateur in a Surrey clay pit Baryonyx Psittacosaurus: 137.1–100.5 Ma · The best-understood dinosaur: colour, skin, bristles and even its cloaca are known Psittacosaurus Utahraptor: 137.1–132.6 Ma · The largest raptor, with a 24-centimetre killing claw Utahraptor Spinosaurus: 125.8–72.2 Ma · The longest predatory dinosaur, a sail-backed river hunter with a paddle tail Spinosaurus Sinosauropteryx: 125.8–119.6 Ma · The first non-bird dinosaur found with feathers, and the first with a known colour Sinosauropteryx Yutyrannus: 125.8–119.6 Ma · A nine-metre tyrannosaur relative covered in shaggy feathers Yutyrannus Amargasaurus: 125.8–121.4 Ma · A small sauropod with a double row of spines down its neck Amargasaurus Concavenator: 125.8–121.4 Ma · A Spanish predator with a strange hump before the hips and possible quill knobs Concavenator Microraptor: 121.4–113.2 Ma · A crow-sized dinosaur with four wings and glossy black feathers Microraptor Borealopelta: 121.4–113.2 Ma · An armoured dinosaur so well preserved it looks like it is sleeping Borealopelta Ouranosaurus: 121.4–66 Ma · A sail-backed plant-eater from the Sahara, when it was a river delta Ouranosaurus Nigersaurus: 121.4–100.5 Ma · The 'Mesozoic cow' whose vacuum-cleaner mouth held 500 teeth Nigersaurus Patagotitan: 113.2–100.5 Ma · The best-known of the super-giants: six individuals from one Patagonian ranch Patagotitan Giganotosaurus: 113.2–106.3 Ma · A South American predator that rivalled Tyrannosaurus in size Giganotosaurus Leaellynasaura: 113.2–110.1 Ma · A small polar dinosaur that lived through months of winter darkness Leaellynasaura Argentinosaurus: 110.1–106.3 Ma · Possibly the heaviest land animal ever, known from a handful of enormous bones Argentinosaurus Deinocheirus: 100.5–66 Ma · For 50 years only a pair of 2.4-metre arms were known; the rest was a hump-backed, duck-billed surprise Deinocheirus Shantungosaurus: 100.5–66 Ma · The largest duck-bill and the biggest non-sauropod dinosaur known Shantungosaurus Mosasaurus: 100.5–61.7 Ma · A giant marine lizard from the Maastricht chalk, the fossil that launched the idea of extinction Mosasaurus Gallimimus: 93.9–66 Ma · The largest ostrich dinosaur, built for speed on the Gobi plains Gallimimus Velociraptor: 89.8–66 Ma · A turkey-sized, feathered hunter, not the man-sized monster of the movies Velociraptor Oviraptor: 89.8–72.2 Ma · Named an egg thief for a crime it did not commit: it was brooding its own nest Oviraptor Edmontosaurus: 89.8–66 Ma · The duck-bill known from 'mummies' with skin, hooves and a fleshy crest Edmontosaurus Pteranodon: 89.8–72.2 Ma · Not a dinosaur at all: a flying reptile with a seven-metre wingspan and a toothless beak Pteranodon Hadrosaurus: 85.7–66 Ma · The first dinosaur skeleton ever mounted for the public, in Philadelphia in 1868 Hadrosaurus Tyrannosaurus: 83.6–66 Ma · The tyrant king: the most studied predator that ever walked the Earth Tyrannosaurus Triceratops: 83.6–66 Ma · Three horns, a bony frill and the most common large herbivore of the final dinosaur age Triceratops Ankylosaurus: 83.6–66 Ma · A living tank with a bone-crushing tail club Ankylosaurus Parasaurolophus: 83.6–72.2 Ma · A duck-billed dinosaur whose metre-long crest worked like a trombone Parasaurolophus Pachycephalosaurus: 83.6–66 Ma · A dome of solid bone 25 centimetres thick, probably for ramming rivals Pachycephalosaurus Dreadnoughtus: 83.6–72.2 Ma · A giant named after battleships, known from an unusually complete skeleton Dreadnoughtus Maiasaura: 83.6–72.2 Ma · The dinosaur that proved parents cared for their young Maiasaura Troodon: 83.6–66 Ma · The 'smartest dinosaur', with big eyes and a big brain, now a name in trouble Troodon Zuul: 83.6–72.2 Ma · An ankylosaur named after a movie demon, with skin and armour still in place Zuul Carnotaurus: 72.2–66 Ma · A horned predator with the smallest arms of any large theropod Carnotaurus Therizinosaurus: 72.2–66 Ma · A pot-bellied, long-necked theropod with metre-long claws, the longest of any animal Therizinosaurus Nanotyrannus: 72.2–66 Ma · A small tyrannosaur or a teenage T. rex? One of palaeontology's longest arguments Nanotyrannus Majungasaurus: 72.2–66 Ma · The only dinosaur with direct evidence of cannibalism Majungasaurus Austroraptor: 72.2–66 Ma · The largest raptor of the southern hemisphere, with a long snout and short arms Austroraptor Where it was found North America, Portugal · Countries with fossils: DE, FR, PT, US
147 fossil occurrences in the Paleobiology Database · Rock formations: Alcobaça, Lepidotus Beds, Lourinhã, Morrison
Today When alive
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Size Human, 1.8 m Allosaurus · Height 3 m 0 2 4 6 8
Length 9 m · Mass 2 t · Size estimates are editorial, from the literature; silhouettes from PhyloPic.
Length 9 m
Height 3 m
Mass 2 t2,000 kg
First appearance 161.5 MaOxfordian
Last appearance 137.1 MaBerriasian
Span of the fossil record 24.4 million years
Fossil occurrences 147DE, FR, PT, US
Year named 1877Marsh Sources Image: The_Wookies, CC BY 2.5 · CC BY 2.5 · image page
Life restoration: Fred Wierum, CC BY-SA 4.0 · CC BY-SA 4.0 · image page
Silhouette: Scott Hartman (PhyloPic) · license
Text: Wikipedia (CC BY-SA 4.0). Taglines, highlights and size estimates are editorial.
Artist's reconstructionFred Wierum, CC BY-SA 4.0