Pinhead-sized sea creature was a bag with a mouth | Science News

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Pinhead-sized sea creature was a bag with a mouth

Anus may have been absent in odd new fossils from 540 million years ago

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2:00pm, February 3, 2017
deuterostome fossil

MOUTHING OFF  New fossils show tiny creatures with accordion mouths (one shown) that lived 540 million years ago. The animals are the earliest known deuterostomes, a category so big it includes everything from humans to starfish.

A roughly 540-million-year-old creature that may have once skimmed shorelines was a real oddball.

Dozens of peculiar, roundish fossils discovered in what is now South China represent the earliest known deuterostomes, a gigantic category of creatures that includes everything from humans to sea cucumbers.

No bigger than a pinhead, the fossils have wrinkly, baglike bodies and gaping mouths that are pleated around the edges like an accordion, researchers report January 30 in Nature. Unlike most other deuterostomes, the animals don’t seem to have an anus. Instead, the ancient oddities, named Saccorhytus coronarius, may have leaked waste (and other bodily fluids like mucus and sex cells) out of tiny holes lining their sides. These holes may have later evolved into gill slits.

A tough, flexible skin would have protected Saccorhytus as it wriggled through

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