Dino card No. 0215 of 2,027

Avisaurus

Say it: AV-ih-SORE-us

Name means: “bird lizard”1

Ate: MeatEarly birdsLate Cretaceous

Avisaurus was a bird-like dinosaur that lived near the end of the age of dinosaurs. It was a fierce hunter with sharp claws, kind of like a tiny raptor. But it was actually an ancient bird, not a dinosaur!1

Lived

72 to 66 million years ago4

Late Cretaceous

Fossils found in

Montana and North Dakota, USA4 1

Food

Meat1 4

Weight

1.2 kg to 1.7 kg1

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

How heavy was it?

as heavy as 14 bananas

lighter than a house catas heavy as 14 bananas

How big was Avisaurus compared to YOU?

Just maths in your browser. Nothing is saved or sent anywhere.

cool stuff

Fun facts

Avisaurus lived about 68 to 66 million years ago, right before the dinosaurs went extinct.1

It was one of the largest enantiornithine birds, weighing up to 1.7 kilograms (3.7 pounds).1

The first fossil of Avisaurus was a single foot bone called a tarsometatarsus, found in Montana in 1975.1

Scientists first thought Avisaurus was a non-avian dinosaur, but later realized it was an ancient bird.1

Avisaurus had curved claws on its feet, similar to those of raptor dinosaurs, which helped it catch prey.1

It lived in swamps and river basins along the western shore of a huge sea that split North America.1

AI-made picture of Avisaurus — An AI-made picture of how Avisaurus 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 Avisaurus

?Was Avisaurus a dinosaur?

Yes, Avisaurus was a dinosaur. All birds are members of the dinosaur group, and Avisaurus was an enantiornithine bird.1

?How big was Avisaurus?

Avisaurus was a large enantiornithine bird. Avisaurus darwini weighed up to 1.2 kilograms (2.6 pounds), and Avisaurus archibaldi weighed up to 1.7 kilograms (3.7 pounds).1

?What did Avisaurus eat?

Avisaurus was a predator that likely ate other vertebrates. Its curved claws and foot bones suggest it could catch and carry prey, similar to modern hawks and owls.1 2

?When did Avisaurus live?

Avisaurus lived about 68 to 66 million years ago, during the Late Cretaceous period. It was one of the last enantiornithine birds before the non avian dinosaurs went extinct.1

?Where was Avisaurus found?

Avisaurus fossils have been found in the Hell Creek Formation of Montana, USA. The first fossil was a single foot bone collected in 1975 in Garfield County.1

?Could Avisaurus fly?

Yes, Avisaurus was a bird and could fly. Its foot bones show it was a skilled predator that could catch prey, similar to modern birds of prey.2 3

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Myth buster

Myth: Avisaurus was a dinosaur.

Truth: Avisaurus was actually an ancient bird, part of a group called enantiornithines. It was a bird-like dinosaur, but not a non-avian dinosaur.1

For dino experts

Scientific name: Avisaurus
Named by: Brett-Surman and Paul 19854
Group: Early birds
Family / clade: Avisauridae4
Classification: Theropoda > Avialae4
Age of the rocks: 72 to 66 million years (Maastrichtian)4
Rock formations: Hell Creek4
Countries: USA4
Fossil records: 2 in the Paleobiology Database4
Discovery: Avisaurus was named in 1985 by paleontologists Brett-Surman and Paul. The first fossil, a foot bone, was found in 1975 by J. David Archibald in the Hell Creek Formation of Montana.1 4
Still debated: Scientists are not sure exactly how Avisaurus used its claws, whether for hunting or climbing.1

Where the facts come from

Avisaurus (en.wikipedia.org)
Predatory birds from the same fossil formation as SUE the T. rex - Field Museum (fieldmuseum.org)
New enantiornithine diversity in the Hell Creek Formation and the functional morphology of the avisaurid tarsometatarsus (pmc.ncbi.nlm.nih.gov)
Avisaurus in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.

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