Selmasaurus
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
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Fun facts
Selmasaurus had the fewest teeth of any known mosasaur, making it unusual among its relatives.1
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
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
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
Selmasaurus lived about 86 to 80 million years ago, during the Late Cretaceous period.1
Stable isotope studies suggest that Selmasaurus johnsoni sometimes swam in deeper, open ocean waters, not just near the shore like many other plioplatecarpines.1

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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For dino experts
- 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
- Selmasaurus (en.wikipedia.org)
- Selmasaurus in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.
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