The evolution of teeth got pushed back farther in time, thanks to analysis of a placoderm fossil.

According to Science Magazine’s Science Shot, “Ancient Jaws Had Real Teeth.”  Live Science headlined, “Evolution’s Bite: Ancient Armored Fish Was Toothy, Too.”  The best graphics are on PhysOrg’s coverage, “Looking for the evolutionary origins of our pretty smile.”

The artist’s rendition of this shark-like fish’s smile is anything but pretty.  Neither is the evolutionary implication, stated on Science Shot: “The evolutionary origin of teeth and jaws has long been shrouded in mystery, but the new findings reveal that even the earliest jawed vertebrates had choppers.”

Placoderms supposedly lived between 360–420 million years ago, far earlier than expected for vertebrate teeth.  The placoderm teeth had no roots, and grew out of the jawbone, but otherwise were clearly adapted for big bites.  What it means is that jaws had teeth from the beginning; teeth were not a later addition.

“It has long been thought that the first jawed vertebrates were gummy— [they had] jaws without teeth, capturing prey by suction-feeding,” researcher Philip Donoghue, a paleontologist at the University of Bristol in England, told LiveScience.

But even though Donoghue claimed this study “solves the debate on the origin of teeth,” it would seem more challenging to explain the origin of both jaws and teeth at the same time.  Live Science said, “This discovery that the earliest jawed vertebrates were toothy suggests teeth evolved along with or soon after jaws did.”…

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