Angolasaurus bocagei: New Mosasaur Species Uncovered in Kansas

Tuesday, August 31, 2021

A life reconstruction of the plioplatecarpine mosasaur Angolasaurus bocagei, alongside the turtle Angolachelys mbaxi. Image credit: Henry Sharpe / CC BY-SA 4.0.

A new species of the mosasaur genus Ectenosaurus has been identified from the fossilized remains found in western Kansas, the United States.

The newly-identified mosasaur species lived during the Late Cretaceous epoch, some 80 million years ago.

The ancient creature inhabited the Western Interior Seaway, a shallow body of marine water that divided the North American continent into two distinct landmasses.

Named Ectenosaurus everhartorum, it is only the second species in the Ectenosaurus genus.

The marine animal was about 5.5 m (18 feet) long, and resembled the false gharial (Tomistoma schlegelii).

“If Ectenosaurus clidastoides with its long, slender jaws resembles a gharial crocodile, the new species is closer to a false gharial crocodile with notably blunter jaws,” said Dr. Takuya Konishi, a paleontologist in the Department of Biological Sciences at the University of Cincinnati.

Willman et al. made scientific drawings of Ectenosaurus everhartorum’s jawbone to help understand its taxonomy and to compare it with the jawbone of a similar species, Ectenosaurus clidastoides (labeled D). Image credit: Willman et al., doi: 10.1139/cjes-2020-0175.

The fossilized jaw of Ectenosaurus everhartorum was collected in the 1970s in Logan County, western Kansas.

“Mosasaurs in western Kansas have been well sampled and well researched,” Dr. Konishi said.

“Those two factors create tall odds when you try to find something new.”

Ectenosaurus mosasaurs are unusual for how few specimens have been found in the genus compared to other mosasaurs.

“In western Kansas we have over 1,500 mosasaur specimens,” Dr. Konishi said.

“Out of those we can only find one specimen each representing these two species of Ectenosaurus. That’s sort of crazy.”

The discovery is reported in a paper in the Canadian Journal of Earth Sciences.


Alexander J. Willman et al. A new species of Ectenosaurus (Mosasauridae: Plioplatecarpinae) from western Kansas, USA, reveals a novel suite of osteological characters for the genus. Canadian Journal of Earth Sciences, published online August 26, 2021; doi: 10.1139/cjes-2020-0175