Dino card No. 0564 of 2,027

Edgarosaurus

Say it: ed-gar-oh-SORE-us

Name means: “Edgar's lizard”3

Ate: MeatPlesiosaursEarly Cretaceous to Late CretaceousNot technically a dinosaur

Edgarosaurus was a short-necked plesiosaur that swam in the warm, shallow sea that once covered Montana. It used its long snout and sharp teeth to catch fish and other slippery prey.1 2

Fun fact: this sea reptile swam while dinosaurs walked on land. Everyone calls them dinos, but they were a different branch of reptiles.

Lived

106 to 94 million years ago3

Early Cretaceous to Late Cretaceous

Fossils found in

Montana, USA3

Food

Meat2

Length

3.5 m2

estimated

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

How long was it?

as long as 4 dogs nose to tailas long as 19 bananas end to end

How big was Edgarosaurus compared to YOU?

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cool stuff

Fun facts

Edgarosaurus had a short neck and a long snout, unlike the long-necked plesiosaurs like Elasmosaurus.1

Its skull is one of the oldest and best-preserved plesiosaur skulls from the Cretaceous of North America.1

Edgarosaurus had 26 neck bones, which is more than some other short-necked plesiosaurs like Dolichorhynchops (which had 19).2

It had a small opening in the top of its skull called a pineal foramen, which some other plesiosaurs lacked.2

The only known fossil of Edgarosaurus was found in the Thermopolis Shale, which was once the bottom of the Western Interior Seaway.1

Edgarosaurus lived about 106 to 94 million years ago, during the Late Cretaceous period.2

AI-made picture of Edgarosaurus — An AI-made picture of how Edgarosaurus 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.

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For dino experts

Scientific name: Edgarosaurus
Named by: Druckenmiller 20023
Group: Plesiosaurs
Family / clade: Polycotylidae3
Classification: Plesiosauria > Sauropterygia3
Age of the rocks: 106 to 94 million years (Albian / Cenomanian)3
Rock formations: Thermopolis Shale3
Countries: USA3
Fossil records: 1 in the Paleobiology Database3
Discovery: Edgarosaurus was named by Pat S. Druckenmiller in 2002, based on a partial skeleton found in Montana. The type specimen includes a complete skull, many vertebrae, and a forelimb.1 3
Still debated: Scientists are not sure exactly how Edgarosaurus is related to other plesiosaurs. Some place it in the group Polycotylidae, but its exact family tree is still debated.1

Where the facts come from

Osteology of a new plesiosaur from the lower Cretaceous (Albian) Thermopolis Shale of Montana (tandfonline.com)
PBDB Taxon (paleobiodb.org)
Edgarosaurus in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.

Every fact on this page has a number that points to its source. If we got something wrong, sorry, we are dino fans, not a science journal. Tell us at [email protected] and we will fix it.

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