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Acrocanthosaurus

Say it: ah-kroh-kan-tho-SORE-us

Name means: “high-spined lizard”1

Ate: MeatMeat-eating dinosEarly Cretaceous to Late Cretaceous

Acrocanthosaurus was a huge meat-eating dinosaur that lived in North America about 110 million years ago. It had a row of tall spines along its back, neck and tail that made it look like a giant lizard with a fin. It was the biggest predator in its time, even before T. rex appeared.1 2

Lived

121 to 94 million years ago4

Early Cretaceous to Late Cretaceous

Fossils found in

Oklahoma, Texas, Maryland, and possibly other southeastern states, USA2 4

Food

Meat2

Length

up to 12 m1

Weight

up to 2.6 tonnes2

Height

up to 4 m2

at the hips

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

How long was it?

How tall was it?

at the hips

How heavy was it?

as heavy as 1.5 cars

as long as 2.5 cars parked in a rowas long as 67 bananas end to endas heavy as 87 big dogsas heavy as 520 watermelonsas tall as 2 doors stacked up

How big was Acrocanthosaurus compared to YOU?

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cool stuff

Fun facts

Acrocanthosaurus had 68 thin, knife-like teeth in its 1.4 metre long skull.2

Its arms were each about 0.9 metres long and ended in three sharp, curved claws used to grip and tear prey.2

Fossilized footprints show that Acrocanthosaurus ran alongside its prey and then lunged, attacking like a modern lion but slower.2

Only four skeletons of Acrocanthosaurus have ever been found, making it a very rare dinosaur.2

Acrocanthosaurus lived about 110 million years ago, which is 45 million years before T. rex walked the Earth.2

Its eyes faced sideways, so it had to tilt its head to look at prey with one eye.2

AI-made picture of Acrocanthosaurus — An AI-made picture of how Acrocanthosaurus might have looked, made by a computer from what scientists know. It is a guess: the real animal may have looked different, and nobody knows its true colours.

you asked

Most asked questions about Acrocanthosaurus

?How big was Acrocanthosaurus?

Acrocanthosaurus was about 11 to 11.5 metres (36 to 38 ft) long and weighed between 4.4 and 8.4 metric tons (4.9 and 9.3 short tons).3 1

?Was Acrocanthosaurus bigger than T. rex?

No, T. rex was generally heavier and more robust. While length estimates are similar, T. rex was typically bulkier than Acrocanthosaurus.2

?What did Acrocanthosaurus eat?

Acrocanthosaurus was a meat-eater that preyed on dinosaurs larger than itself, like the sauropod Pleurocoelus, as well as ornithopods and ankylosaurs.2 3

?When did Acrocanthosaurus live?

Acrocanthosaurus lived during the Early Cretaceous Period, about 110 million years ago, which is 45 million years before T. rex appeared.2 1

?Why did Acrocanthosaurus have a fin on its back?

Scientists are unsure what the tall spines on its back were for. They might have helped control body temperature, store fat, or communicate with others.2 3

?How fast could Acrocanthosaurus run?

Acrocanthosaurus probably could not run very fast. Its leg bones suggest it was not a fast runner, and it attacked like a modern lion but at a slower pace.3 2

?Where was Acrocanthosaurus found?

Acrocanthosaurus fossils have been found in Oklahoma, Texas, Wyoming, and Maryland in the United States. It lived across much of North America.3 1

?Is Acrocanthosaurus related to T. rex?

No, Acrocanthosaurus belonged to a different family of dinosaurs. It was more closely related to Allosaurus than to T. rex.2

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Myth buster

Myth: Acrocanthosaurus is a type of tyrannosaur, related to T. rex.

Truth: Acrocanthosaurus belonged to a different family called Carcharodontosauridae, more closely related to Allosaurus. Tyrannosaurs had two fingers on each hand, while Acrocanthosaurus had three.2

For dino experts

Scientific name: Acrocanthosaurus
Named by: Stovall and Langston 19504
Group: Meat-eating dinos
Family / clade: Carcharodontosauridae4
Classification: Theropoda > Allosauroidea > Carcharodontosauridae4
Age of the rocks: 121 to 94 million years (Aptian / Cenomanian)4
Rock formations: Antlers, Cloverly, Arundel Clay4
Countries: USA4
Fossil records: 14 in the Paleobiology Database4
Discovery: Acrocanthosaurus was named in 1950 by paleontologists J. Willis Stovall and Wann Langston, Jr. The first fossils were found in Atoka County, Oklahoma, which gave the species its name atokensis.1 2
Still debated: Scientists are not sure what the tall spines on Acrocanthosaurus's back were used for. They might have helped control body temperature or been used for display.2

Where the facts come from

Acrocanthosaurus | Natural History Museum (nhm.ac.uk)
Frequently Asked Questions (naturalsciences.org)
Acrocanthosaurus (en.wikipedia.org)
Acrocanthosaurus in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.

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