Dino card No. 1452 of 2,027

Plesiotylosaurus

Say it: PLEE-see-oh-TIE-loh-SORE-us

Name means: “near Tylosaurus”1

Ate: MeatMosasaursLate CretaceousNot technically a dinosaur

Plesiotylosaurus was a giant marine lizard that swam in the warm seas of the Late Cretaceous. It was not a dinosaur, but a fierce predator with a long, powerful body and a skull full of sharp teeth.1

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

Lived

72 to 66 million years ago3

Late Cretaceous

Fossils found in

Moreno Formation in California, USA1 3

Food

Meat3 1

Length

6 m1

estimated from the lower jaw length of the holotype

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

How long was it?

as long as 6 dogs nose to tailas long as 33 bananas end to end

How big was Plesiotylosaurus compared to YOU?

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cool stuff

Fun facts

Plesiotylosaurus had a bony rostrum (a kind of snout tip) that stuck out in front of its teeth, which is unusual among mosasaurs.1

Its lower jaw alone was nearly 1 meter (3.2 feet) long, about the height of a 3-year-old child.1

Plesiotylosaurus had teeth on the roof of its mouth (pterygoid teeth) that were almost as big as its regular teeth.1

Even though its name means 'near Tylosaurus', Plesiotylosaurus is not closely related to Tylosaurus. They just evolved similar skull features separately.1

The holotype skull of Plesiotylosaurus was found in the Panoche Hills of California, and it is a bit squashed but still mostly complete.1

Plesiotylosaurus lived about 70 to 66 million years ago, right at the end of the Age of Dinosaurs.1

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

?How big was Plesiotylosaurus?

About 6 metres (20 feet) long, based on its 98 cm (3.22 feet) lower jaw. Some estimates suggest around 6.5 metres.1 2

?What did Plesiotylosaurus eat?

It was a carnivore and probably ate tough prey like marine turtles, which are found in the same rocks. Its robust skull and strong jaws suggest it could handle hard-shelled animals.1 2

?Was Plesiotylosaurus a dinosaur?

No, it was a marine lizard belonging to the mosasaur family, not a dinosaur. It swam in the sea during the Late Cretaceous.1

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For dino experts

Scientific name: Plesiotylosaurus
Named by: Camp 19423
Group: Mosasaurs
Family / clade: Mosasauridae3
Classification: Mosasauroidea3
Age of the rocks: 72 to 66 million years (Maastrichtian)3
Rock formations: Moreno3
Countries: USA3
Fossil records: 2 in the Paleobiology Database3
Discovery: Plesiotylosaurus was named by C. L. Camp in 1942 based on a skull and jaws found in the Moreno Formation of California.1 3
Still debated: Scientists still debate whether Plesiotylosaurus should be considered a separate genus or if it is actually a species of Prognathodon, because their skulls are so similar.1

Where the facts come from

Plesiotylosaurus (en.wikipedia.org)
Plesiotylosaurus (prehistoric-wildlife.com)
Plesiotylosaurus 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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