Dino card No. 0563 of 2,027

Ectenosaurus

Say it: ek-ten-oh-SORE-us

Name means: “drawn-out lizard”1

Ate: MeatMosasaursLate CretaceousNot technically a dinosaur

Ectenosaurus was a fast-swimming marine lizard that lived in the Late Cretaceous seas. It had a very long snout and a stiff body, so it moved by wagging its tail like a fish. This rare mosasaur was a top predator in the ancient ocean.1 3

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

Lived

90 to 72 million years ago3

Late Cretaceous

Fossils found in

Kansas, Alabama, and Texas, USA1 3

Food

Meat3

Length

5 to 6 m1

estimated from skull length of 64.5 cm

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

as long as 3 bicycles in a rowas long as 33 bananas end to end

How big was Ectenosaurus compared to YOU?

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cool stuff

Fun facts

Ectenosaurus had tiny scales, only 2.7 by 2.0 millimetres, which were smaller than those of other mosasaurs of similar size.1

Its body was stiff in the front, so it could not slither like a snake. Instead, it used its tail fin to push through the water.1

Scientists have found skin impressions from Ectenosaurus that show a complex mesh of fibers, helping them understand how it swam.1

Ectenosaurus is one of the rarest mosasaurs, but it had at least four different species.2

Stable isotope studies suggest that Ectenosaurus lived in open ocean waters, not just near the shore.1

The first Ectenosaurus fossil was originally thought to be a species of Platecarpus, but later scientists gave it its own genus.1

AI-made picture of Ectenosaurus — An AI-made picture of how Ectenosaurus 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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Myth buster

Myth: Some people think mosasaurs like Ectenosaurus swam by wiggling their whole body like a snake.

Truth: Actually, Ectenosaurus had a stiff front body and used only its tail for swimming, much like modern whales.1

For dino experts

Scientific name: Ectenosaurus
Named by: Russell 19673
Group: Mosasaurs
Family / clade: Mosasauridae3
Classification: Mosasauroidea3
Age of the rocks: 90 to 72 million years (Coniacian / Campanian)3
Rock formations: Niobrara, Pen, Mooreville Chalk3
Countries: USA3
Fossil records: 5 in the Paleobiology Database3
Discovery: The first fossil was found in Logan County, Kansas, and was named Platecarpus clidastoides by John C. Merriam in 1894. Dale Russell renamed it Ectenosaurus in 1967.1
Still debated: Scientists are not sure whether Ectenosaurus belongs in the subfamily Plioplatecarpinae or is more closely related to mosasaurines like Prognathodon.1

Where the facts come from

Ectenosaurus (en.wikipedia.org)
Two new plioplatecarpine mosasaurs (Mosasauridae; Plioplatecarpinae) of the genus Ectenosaurus from the Upper Cretaceous of North America (escholarship.org)
Ectenosaurus 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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