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Selmasaurus

Say it: sel-muh-SORE-us
Name means: “Selma lizard, after the Selma Group of rocks in Alabama”1
Ate: MeatMosasaursLate CretaceousNot technically a dinosaur

Selmasaurus was a small, fierce marine lizard that lived in the shallow seas of North America during the time of the dinosaurs. It had a stiff skull that could not stretch like other mosasaurs, so it ate smaller prey. Two species are known, one from Alabama and one from Kansas.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
86 to 72 million years ago2
Late Cretaceous
Fossils found in
Alabama and Kansas, USA21
Food
Meat21
Length
3 to 5 m1
estimated

When did it live?

Triassic
Jurassic
Cretaceous
252 million years ago20114566, the asteroid

How big was it?

How long was it?

Selmasaurus about 5 m longA bicycle about 1.8 mA car about 4.5 mAn elephant, the biggest land animal today about 6.5 mA house about 10 m
as long as 5 dogs nose to tailas long as 28 bananas end to end

How big was Selmasaurus compared to YOU?

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cool stuff

Fun facts

1

Selmasaurus had the fewest teeth of any known mosasaur, making it unusual among its relatives.1

2

Unlike most mosasaurs, Selmasaurus could not widen its jaws to swallow big prey. Its skull was stiff and did not have the flexible joints that other mosasaurs used to eat large animals.1

3

The first Selmasaurus fossil was a skull found in Alabama, but for many years no one knew exactly which rock layer it came from. In 1998, scientists used tiny fossils from the skull to figure out its age.1

4

One species, Selmasaurus johnsoni, was discovered by a family in Kansas in 1996 and donated to a museum. Its skull is one of the most complete mosasaur skulls ever found.1

5

Selmasaurus lived about 86 to 80 million years ago, during the Late Cretaceous period.1

6

Stable isotope studies suggest that Selmasaurus johnsoni sometimes swam in deeper, open ocean waters, not just near the shore like many other plioplatecarpines.1

AI-madeAI-made picture of Selmasaurus
An AI-made picture of how Selmasaurus 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 Selmasaurus

?How big was Selmasaurus?

Selmasaurus was a small mosasaur, about 3 to 5 metres (10 to 16 feet) long.1

?What did Selmasaurus eat?

Selmasaurus was a predator that ate smaller prey. Because its skull could not stretch open wide, it could not swallow large animals like other mosasaurs.1

?Is Selmasaurus a dinosaur?

No, Selmasaurus is not a dinosaur. It is a marine lizard called a mosasaur that lived in the sea during the time of the dinosaurs.1

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Scientific name
Selmasaurus
Named by
Wright and Shannon 19882
Group
Mosasaurs
Family / clade
Mosasauridae2
Classification
Mosasauroidea2
Age of the rocks
86 to 72 million years (Santonian / Campanian)2
Rock formations
Mooreville Chalk, Niobrara2
Countries
USA2
Fossil records
2 in the Paleobiology Database2
Discovery
Selmasaurus was first named in 1988 by Kenneth Wright and Samuel Shannon, based on a skull found in Alabama. The species S. russelli was named after paleontologist Dale Russell. A second species, S. johnsoni, was discovered in Kansas in 1996 and named in 2008.1
Still debated
Scientists are still debating exactly how Selmasaurus is related to other mosasaurs. Some think it is closely related to Ectenosaurus, while others place it in a group called Selmasaurini with Gavialimimus and Goronyosaurus.1

Where the facts come from

  1. Selmasaurus (en.wikipedia.org)
  2. Selmasaurus in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.

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More from the same group: Mosasaurs

Also from the same time: Late Cretaceous

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