423-million-year-old Armored Fish
[1.]: Qilinyu Rostrata, A 423-million-year-old fish from China with a dolphin like head and a body like a tank, the armored fish had jaws that resemble those of modern land vertebrates and bony fish. The discovery of the Armored Fish from China researchers report in the Oct. 21 science that the jaws of all modern land vertebrates and bony fish originated in a bizarre group of animals called Placoderms.
Qilinyu Rostrata, I a different Placoderm fossil from 2013, the new find named Qilinyu Rostrata, is helping rewrite the story of early vertebrate evolution, says paleontologist John Maisey of the American Museum of Natural History in New York City “We’ve suddenly realized we had it all wrong”, and as we all know all to well this is common.; He says.
The jaws of humans – and dogs, salmon, lizards and all other bony vertabrates – contain three key bones: the maxilla and premaxilla of the upper jaw, and the dentary of the lower jaw.
Coauthor Per Ahlberg, a paleontologist at Uppsala University, Sweden, said. “Anything from a human being to a cod has recognizably the same set of bones in the head” and he also said. “Where did these bony jaws come from?” More than a hundred million years before dinosaurs walked the earth, a type of fish called Placoderms thrived animals, but their jaws were unusual, Ahlberg said. “They look like sheet metal cutters, they’re these horrible bony blades that slice together.”
The blades were called gnathal plates, they looked so peculiar that most scientists thought that the three part jaws of humans originated in an early bony fish and that Placoderms were just a funny little side branch in the vertebrate family tree.
Placoderms are a highly debated group of animals and no one new were to place them says Martin Brazeau a paleontologist from Imperial Collage London.
In 2013, Ahlberg and his colleagues found a new clue in a 419 million year old fossil that had the body of a Placoderm. An animal called Entelognathus Primordialis. The work bolstered the idea that Placoderms weren’t their own odd group that dead-ended hundreds of million years ago-some were actually the ancestor of the bony fish.
Two animals, though, is a different story. “This is part of our early evolutionary history, it shows where our own jaws came from.”
[2.]: Qilinyu Rostrata: Another interesting relationship is the Entelognathus Primordialis. Now, these Qilinyu fish-ancestors lived 423 million years ago, during the Silurian Period. It was discovered in China’s Yunnan province. Credit: Dinghua Yang / Chinese Academy of Sciences.
An ancient fish called Qilinyu Rostrata is helping re-write early vertebrate evolutionary history, claims an international team of researchers.
Qilinyu Rostrata: They found that the group the fish belongs to, called Placoderms, is responsible for giving jaws to all ancient fish, and later down the evolutionary line humans too.
Qilinyu Rostrata: Previously, scientists thought Placoderms were an odd group of ancient fish which eventually reached an evolutionary dead end.
Qilinyu Rostrata: But in 2013, Per Ahlberg, a paleontologist at Uppsala University in Sweden, discovered a peculiar 419-million-year-old fossil called Entelognathus primordialis that had the body of a Placoderm but showed the familiar three-bone jaw all vertebrates possess today.
These bones are the maxilla and premaxilla of the upper jaw and the dentary of the lower jaw.
Qilinyu Rostrata: Judging from what Ahlberg and colleagues knew from fossil records, this animal should have never existed — but there it was.
“Anything from a human being to a cod has recognizably the same set of bones in the head,” Ahlberg told Science News.
“Where did these bony jaws come from?”
Scientists suspected Placoderms were early-jaw animals given that we’ve seen them in the fossils. Well, sort of.
Qilinyu Rostrata: These looked nothing like the three-boned jaws we’re familiar with and instead resembled cutting blades.
Though still debatable, most people seemed to agree that we have to look elsewhere for jaw ancestors.
Qilinyu Rostrata: Finding Entelognathus .p turned this thinking upside down, but it was only one fossil. Two however — that’s an entirely different story.
The presence of Entelognathus .p and Qilinyu r., which is four million years older, seems to suggest that all later fish owe their jaws to Placoderms.
Qilinyu Rostrata: Moreover, the two species form almost perfect intermediates between Placoderms and bony fish, said., Ahlberg.
“Now we know that one branch of Placoderms evolved into modern jawed vertebrates,” study co-leader Zhu Min, a paleontologist at Chinese Academy of Sciences’ Institute of Vertebrate Paleontology and Paleoanthropology “In this sense, Placoderms are not extinct.”