The identification of a new species belonging to the marine mammal group Desmostylia has intensified the rare animal's brief mysterious journey through prehistoric time, finds a new study.
A big, hippo-sized animal with a long snout and tusks -- the new species, 23 million years old, has a unique tooth and jaw structure that indicates it was not only a vegetarian, but literally sucked vegetation from shorelines like a vacuum cleaner, said vertebrate paleontologist and study co-author Louis L. Jacobs, Southern Methodist University, Dallas.
But unlike other marine mammals alive today -- such as whales, seals and sea cows -- desmostylians went totally extinct. Desmostylians, every single species combined, lived in an interval between 33 million and 10 million years ago.
Their strange columnar teeth and odd style of eating don't occur in any other mammal, The new specimens -- from at least four individuals -- were recovered from Unalaska, an Aleutian island in the North Pacific.
While alive, the creatures lived in what is now Unalaska's Dutch Harbor, where fishing boats depart on Discovery channel's "Deadliest Catch" reality TV show.
"The new animal -- when compared to one of a different species from Japan -- made us realize that desmos do not chew like any other animal," said Jacobs, a professor of earth sciences. "They clench their teeth, root up plants and suck them in."
To eat, the animals buttressed their lower jaw with their teeth against the upper jaw, and used the powerful muscles that attached there, along with the shape of the roof of their mouth, to suction-feed vegetation from coastal bottoms. Big muscles in the neck would help to power their tusks, and big muscles in the throat would help with suction.
"No other mammal eats like that," Jacobs said. "The enamel rings on the teeth show wear and polish, but they don't reveal consistent patterns related to habitual chewing motions."
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