Ancient armored fish revises early history of jaws

Science News ^ | 10/20/16 | Meghan Rosen

[JimSEA]

A freaky fish with a head like a dolphin and a body like a tank may be to thank for human jaws.

The discovery of a 423-million-year-old armored fish from China suggests that the jaws of all modern land vertebrates and bony fish originated in a bizarre group of animals called placoderms, researchers report in the Oct. 21 Science.

“We’ve suddenly realized we had it all wrong,” he says.

The jaws of humans — and dogs, salmon, lizards and all other bony vertebrates — contain three key bones: the maxilla and premaxilla of the upper jaw, and the dentary of the lower jaw.

“Anything from a human being to a cod has recognizably the same set of bones in the head,” says study coauthor Per Ahlberg, a paleontologist at Uppsala University in Sweden. The big question, he says, is “Where did these bony jaws come from?”

More than a hundred million years before dinosaurs walked the Earth, fishes called placoderms thrived under water. Scientists knew that these armored fishes were early jawed animals, but their jaws were unusual: “They look like sheet metal cutters,” Ahlberg says. “They’re these horrible bony blades that slice together.”

[BroJoeK]

Amendment10: "The 'laws' of evolution are evidently as politically correct as global warming 'science.'
This is evidenced by evolution laws being revised every time a dog digs up a strange bone in the backyard."

Are you joking?
There are no "laws" of evolution, or global warming for that matter.
Science proper is basically about three things:

1. confirmed observations = facts, i.e., descent with modifications and natural selection.

2. testable explanations = hypotheses, i.e., various abiogenetic origin of life proposals.

3. confirmed hypothesis = theory, i.e., Darwin's basic evolution theory.

Yes, some scientific ideas are honored as "laws" -- formulas found to work consistently.
Newton's "laws" of motion come to mind, even though Einstein's relativity theory shows they don't always apply.

But science, especially evolution, is all about searching for new data to confirm or help modify previous hypotheses & theories.

Evolution of jaws: