According to researchers, a large haul of fossilized fish teeth in southern China includes the oldest teeth ever discovered. The findings may assist researchers in determining how our aquatic ancestors acquired their bite.
The fossils provide new insights into a crucial period of evolution that has been difficult to understand due to the scarcity of fossils from that time period. In a series of four studies published on Wednesday in the journal Nature, researchers describe some of their discoveries, including ancient teeth and previously unknown species.
The fossils date back to the Silurian period, which was significant for life on Earth from 443 to 419 million years ago. Scientists believe that around this time, our ancestors with backbones who were still swimming around on a watery planet began to develop teeth and jaws.
This allowed the fish to hunt for prey instead of filtering food from the muck as bottom feeders. According to Philip Donoghue, a paleontologist at the University of Bristol and co-author of one of the studies, it also triggered a series of other changes in their anatomy, including the development of different types of fins.
Donoghue stated, “It is precisely at this interface between the Old World and the New World.”
A 40-times-magnified model of prehistoric fish teeth is displayed at a press conference on September 28, 2022 in Beijing. WANG ZHAO/AFP courtesy of Getty Images
Matt Friedman, a paleontologist from the University of Michigan who was not involved in the study, noted that in the past, scientists have not found many fossils that demonstrate this shift. They have relied on remnants from the period, such as a piece of spine here and a piece of scale there.
The fossils from China are anticipated to fill in some of these gaps as they are examined by scientists from around the world.
In 2019, a field team discovered the fossil trove, according to an email from Min Zhu, a paleontologist at the Chinese Academy of Sciences who led the research. Researchers explored a pile of rocks near a roadside cliff on a rainy day, following a disappointing expedition that yielded no fossils. When they cracked open a rock, they discovered fossilized fish heads staring back at them.
After transporting additional rocks back to the lab for examination, the research team obtained a vast assortment of fossils in excellent condition for their age.
Per Erik Ahlberg, an author on one of the studies and a professor at Sweden’s Uppsala University, stated that the most common species was a small boomerang-shaped fish that likely used its jaws to snag worms.
A second fossil depicts a shark-like creature with frontal osseous armor, an unusual combination. A well-preserved jawless fish provides insight into the evolution of ancient fins into arms and legs. While heads of these fish are commonly discovered as fossils, Donoghue explained that this specimen included the entire body.
The teeth are also present. The researchers found what they call tooth whorls, which contain multiple teeth. According to Zhu, the fossils are 14 million years older than any other teeth discovered from any species, making them the earliest solid evidence of jaws to date.
Alice Clement, an evolutionary biologist at Australia’s Flinders University who was not involved in the study, described the fossil discovery as “remarkable” and as having the potential to rewrite scientists’ understanding of this time period.
Even though the following evolutionary epoch is known as the “Age of Fishes,” a wide variety of fossils suggests there were plenty of toothy creatures swimming around at this time, according to Clement’s email.