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

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

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