Extinct Hippo-Sized Marine Animals Were Diverse And Ate Like Vacuum Cleaners, Say Researchers

Unlike most other marine animals, every single member of the Desmostylia species lived and died within a brief time – between 33 million and 10 million years ago – before going extinct. While scientists have not determined the cause of the hippo-sized animals' mass exit, their unusual feeding technique may have had something to do with it. To get to the bottom of that question, researchers are poring over recently discovered fossils – 23 million-years-old – that are already proving how diverse the species was.

Compared to its large relatives, these "little guys" had powerful neck, throat and mouth muscles and a unique tooth and jaw structure that all worked together to help them suction-feed vegetation from coastal bottoms like a vacuum cleaner, an odd eating style is not found in any other mammals.

"The new animal -- when compared to one of a different species from Japan -- made us realize that desmos (Desmostylia) do not chew like any other animal," Louis L. Jacobs, study co-author and a vertebrate paleontologist from the Southern Methodist University, Dallas, said in a news release. "They clench their teeth, root up plants and suck them in."

"No other mammal eats like that," Jacobs added. "The enamel rings on the teeth show wear and polish, but they don't reveal consistent patterns related to habitual chewing motions."

The fossils excavated from Unalaska, an Aleutian island in the North Pacific, also represent a new genus, meaning members of the Desmostylia evolved with different tooth and jaw characteristics. This suggests that the Desmostylia family is larger and more diverse than researchers previously thought.

"Our new study shows that though this group of strange and extinct mammals was short-lived, it was a successful group with greater biodiversity than had been previously realized," Anthony Fiorillo, co-author and vice president of research and collections and chief curator at the Perot Museum of Nature and Science, said in a statement.

Their findings were recently published in the journal Historical Biology.

A video detailing their findings can be found online, courtesy of YouTube.

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