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Researchers say they have discovered how humans got teeth. The researchers are Uppsala University in Sweden. They say that human teeth "first evolved 400 million years ago". They believe our teeth came an ancient fish called an acanthothoracid. The researchers studied a fossil the fish. It was difficult to study because the fish is encased rock. The researchers had to use the strongest X-ray machine the world to analyse it. They used the X-ray machine to "digitally dissect" the fish. The researchers discovered that the fish's teeth were amazingly similar to human teeth. The researchers also said humans and 60,000 species jawed vertebrates living Earth today come this fish.

The researchers say the acanthothoracid was one the earliest jawed vertebrates teeth ever to live. They were very excited seeing how similar its teeth were to ours. A co-author the study, Professor Per Ahlberg, said: "These findings change our whole understanding the origin teeth." He commented the similarity to the fish, saying: "Their jawbones resemble those bony fish and seem to be directly ancestral to our own. When you grin the bathroom mirror in the morning, the teeth that grin back at you can trace their origins right back to the first jawed vertebrates." Another researcher said: "Nobody expected to find teeth so deep the evolutionary tree."

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