About 66 million years ago, a giant asteroid crashed into Earth, causing one of the most devastating events in Earth’s history. This impact sparked global fires, caused dramatic climate change, and wiped out the dinosaurs along with countless other species. But new research also suggests that this catastrophe may have opened the door for life to recover much sooner than scientists once thought.
Led by researchers at the University of Texas at Austin, geologynew species of plankton emerged less than 2,000 years after the impact.
The pace of evolution is unusually fast compared to what scientists typically see in the fossil record, said Chris Lowery, lead author of the study and associate professor at the Jackson School of Geosciences at the University of Texas Geophysical Institute (UTIG). The formation of new species typically occurs over millions of years.
“It’s unbelievably fast,” Lowry said. “This study helps us understand how quickly new species evolve after extreme events and how quickly the environment began to recover after the Chicxulub impact.”
Rethinking the timeline of life recovery after the effects of Chicxulub
Previous work by Lowery and colleagues studying the Chicxulub crater in the Gulf of Mexico had already shown that some of the surviving organisms returned to the area fairly quickly after the impact. Still, scientists generally believed that the first new species would not appear until tens of thousands of years later.
This estimate was based on the assumption that post-extinction sediment accumulates at approximately the same rate as before. Researchers are using global geological formations formed from debris thrown into the atmosphere by impacts to define the beginning and end of mass extinctions. This layer is known as the K/Pg boundary.
Lowy and his co-authors point out that this assumption overlooked the major environmental changes that occur when terrestrial and marine ecosystems collapse. Large-scale extinctions have changed the way sediment accumulates in this boundary layer.
How extinctions changed sediment accumulation
Many species of calcareous plankton, which normally sink to the ocean floor, disappeared in this extinction event. At the same time, the loss of most of the land’s vegetation led to increased erosion and additional material was washed into the ocean.
These changes had a major impact on the rate at which sediment was deposited in different regions. This made it difficult to determine the true age of the small fossils preserved in these layers by relying solely on sedimentation rates.
Helium-3 isotope reveals more precise timeline
To refine the timeline, the researchers turned to previously published data on isotopic markers found within the K/Pg boundary. This marker provides a more reliable way to measure the passage of time preserved in the geological record, allowing scientists to pinpoint when different plankton species first appeared in the fossil record.
The isotope known as helium-3 accumulates at a constant rate in marine sediments. As the sediment accumulates more slowly, higher concentrations of helium-3 are present. The faster the sediment accumulates, the lower the concentration. By measuring this isotope, scientists can better estimate how much time passed before the deposit formed.
The research team used helium-3 data from six K/Pg boundary locations in Europe, North Africa, and the Gulf of Mexico to calculate the improvements in sedimentation rates. These measurements helped determine the age of the sediments inhabited by foraminifera, a new species of plankton. parvularglobigerina Yugbina (P. Yugbina), appears for the first time in the fossil record. Scientists often use the word “emergence.” P. Yugbina This is an indicator that the ecosystem is starting to recover after extinction.
New species emerge within a few thousand years
The researchers determined that this plankton species evolved between 35,000 and 11,000 years after the Chicxulub impact, although the exact timing varies depending on where they were studied.
They also identified other plankton species that evolved during the same period. Some of them emerged less than 2,000 years after the asteroid impact, marking the beginning of a long recovery that would gradually restore biodiversity over the next 10 million years.
“The speed of the recovery shows how resilient life is, and it’s truly amazing that complex life can rebuild itself within a geological pulse,” said study co-author Timothy Bralower, a professor in Penn State’s Department of Geosciences. “It may also be reassuring about the resilience of extant species given the threat of human-induced habitat destruction.”
Rapid evolutionary explosion after mass extinction
The study suggests that 10 to 20 new species of foraminifera appeared within about 6,000 years after the impact, although paleontologists are still debating exactly which fossils represent different species.
Overall, the revised timeline shows that evolution can proceed surprisingly quickly under the right conditions. Even after catastrophic mass extinctions, ecosystems can begin to rebuild within just a few thousand years, and new species emerge much faster than scientists previously thought.
