Early evidence of aquatic jaws
A BIG catch of fish fossils in southern China includes the oldest teeth ever found — and may help scientists learn how our aquatic ancestors got their bite.
In a series of four studies, published Wednesday in the journal Nature, researchers detail some of their finds.
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 our backboned ancestors, who were still swimming around on a watery planet, may have started evolving teeth and jaws around this time.
This lets the fish hunt for prey instead of “grubbing around” as bottom feeders. It also sparked a series of other changes in their anatomy, including different kinds of fins, said Philip Donoghue, a University of Bristol palaeontology and an author on one of the studies. “It’s just at this interface between the Old World and the New World,” Donoghue said.
But in the past, scientists haven’t found many fossils to show this shift, said Matt Friedman, a University of Michigan palaeontologist who was not involved in the research.
A field team discovered the fossil trove in 2019, Min Zhu, a palaeontologist at the Chinese Academy of Sciences who led the research, said in an email. On a rainy day, after a frustrating trip that hadn’t revealed any fossils, researchers explored a pile of rocks near a roadside cliff. When they split one rock open, they found fossilised fish heads.
After hauling more rocks back to the lab, the research team wound up with a huge range of fossils that were in great condition for their age. The most common species in the bunch is a little boomerang-shaped fish that likely used its jaws to scoop up worms, said Per Erik Ahlberg of Sweden’s Uppsala University, an author on one of the studies.
Another fossil shows a shark-like creature with bony armour on its front — an unusual combination. A wellpreserved jawless fish offers clues to how ancient fins evolved into arms and legs. While fossil heads for these fish are commonly found, this fossil included the whole body, Donoghue said.
And then there are the teeth. The researchers found bones called tooth whorls 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 of jaws to date, Zhu said. | AP