Ancient Armored Fish May Have Given Humans Jaws

The news about the discovery of an ancient armored fish fossil in China turned out the be much more interesting than considered. This particular placoderm (extinct species of fish) lived in one of tropical sees about 423 million years ago. It was covered with a bony armor and had three plates that were used for cutting food and eating it. The latter characteristic was what made scientists interested in the finding, as the jaws of this species may be connected to the development of human jaws.ancient

The first study on the ancient armored fish was published in the Science journal a couple of days ago. The finding was considered to be Quilinyu rostrata of placoderms, which were the first fish, as well as the first ever vertebrate, which used jaws to hunt and eat.

The first kinds of vertebrates that appeared more than 500 million years ago had tiny mouths which they used to suck smaller creatures. Placoderms turned out to be a major breakthrough in the evolution of life on Earth, having three bones that are also featured in the jaw structures of most modern vertebrates, including humans.

The three bones are the maxilla and premaxilla that create the upper jaw, and the dentary that completes the structure with the lower jaw. The scientists who are working on the study are almost sure these bones in modern structures are the result of evolving from the three plates the ancient armored fish had.

Earlier it was considered that the jaw development began with the first species of bony fish. They appeared later than placoderms, and the new study may change the situation by making 500 million years ago the starting point of the future human jaws development.

The Qilinyu rostrate isn’t the first placoderm fossil to be found. The first one was the Entelognathus that was discovered back in 2013 and was dated a 419-million-year old ancient armored fish. By far there are the only two fossils and both were found near China. They are considered the golden mean between the ancient placoderms and bony fish that developed later.

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With the first fossil finding the scientists were not completely sure about the origins of the fish. The Entelognathus looked like a placoderm, but it had the three-bone jaw that wasn’t a characteristic feature of ancient fish that were not bony fish.

After the second finding – the Quilinyu – the scientists placed both species closer to the placoderm group, but in fact, they are a missing part of a jaw-developing chain between placoderms’ gnathal plates and bony fish jaws.

The Quilinyu rostrata fossil is 5’’ long, and the whole body must be about 8’’. After it was compared to other 372 species of ancient fish, the scientists decided to put in near the Entelognathus, which strengthened the theory about their value in the development of modern vertebrates’ jaws.

The study continues, so it’s not 100% clear whether the theory is true or not. The scientists search for new fossils and investigate the two that were found within recent years, as they may complete the history of human jaws.

http://www.techtimes.com/articles/183158/20161021/armored-prehistoric-fish-in-china-holds-clue-to-where-our-jaws-came-from.htm

http://www.sci-news.com/paleontology/qilinyu-rostrata-silurian-fish-china-jaw-evolution-04297.html

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