NEW YORK (AP) – A large haul of fish fossils in southern China includes the oldest teeth ever found – and may help scientists learn how our aquatic ancestors got their bite.
The discoveries provide new clues about a key period of evolution that was difficult to see because until now scientists had found few fossils from that era. In a series of four studies, published Wednesday in the journal Nature, researchers detail some of their discoveries, from ancient teeth to species never seen before.
The fossils date back to the Silurian period, an important era for life on earth from 443 million years ago to 419 million years ago. Scientists believe that our vertebrate ancestors, who were still floating around on a watery planet, may have started developing teeth and jaws around this time.
This enabled the fish to hunt for prey instead of “grafting around” as bottom feeders, filtering food out of the hull. paleontologist and author of one of the studies.
“It’s right at this interface between the Old World and the New World,” Donoghue said.
But in the past, scientists haven’t found enough fossils to show this change, said Matt Friedman, a University of Michigan paleontologist who was not involved in the research. They rely on fragments from time – a chunk of spine here, a bit of scale there.
It is hoped that the fossils from China will fill some of those gaps as researchers around the world look at them.
A field team found the fossil in 2019, Min Zhu, a paleontologist at the Chinese Academy of Sciences who led the research, said in an email. On a rainy day, after a frustrating trip that turned up no fossils, the researchers explored a pile of rocks near a roadside cliff. When they split one rock open, they found fossilized fish heads staring back at them.
After hauling more rocks back to the lab for examination, the research team ended up with a huge array of fossils in amazing condition for their age.
The most common species in the cruise is a small boomerang-shaped fish that probably used its jaws to scoop up worms, said Per Erik Ahlberg of Sweden’s Uppsala University, an author of one of the studies.
Another fossil shows a shark-like creature with bony armor on its side – an unusual combination. Well-preserved jawless fish provide clues as to how ancient fins evolved into arms and legs. Although fossil heads for these fish are commonly found, this fossil included the entire body, Donoghue said.
And then there are the teeth. The researchers found bones called toothpicks with multiple teeth growing on them. The fossils are 14 million years older than any other teeth found from any species — and provide the earliest solid evidence to date, Zhu said.
Alice Clement, an evolutionary biologist at Flinders University in Australia who was not involved in the research, said the fossil discovery is “significant” and could rewrite our understanding of this period.
The wide variety of fossils suggests there were plenty of toothy creatures swimming around at this time, Clement said in an email, although the next evolutionary era is considered the “Age of Fish.”
The Associated Press Department of Health and Science is supported by the Department of Science Education of the Howard Hughes Medical Institute. The AP is solely responsible for all matters.