A new U.S. study has examined how terrestrial vertebrates were affected at the end of the Permian Period about 252 million years ago when up to 90 percent of ocean creatures went extinct.
A small number of genera, known as “disaster taxa,” survived the mass extinction, and ecosystems are believed to have taken up to eight million years to recover.
The researchers looked at almost 8,600 fossils, originating from Russia and South Africa, from the late Permian to the middle Triassic about 260 million to 242 million years ago.
Based on their analysis, approximately 78 percent of land-based vertebrates appear to have gone extinct. Among the survivors was the taxon Lystrosaurus, comprising reptiles about the size of a large dog, which was scarce before the extinction event, but abundant in the Triassic.
Procolophonids were another group of reptiles that showed a similar pattern of rarity and then dominance.
“It means the (terrestrial ecosystems) were more subject to greater risk of collapse because there were fewer links [in the food web],” said study co-author Jessica Whiteside at Brown University in a press release.
The researchers propose that boom-and-bust cycles followed the mass extinctions like “mini-extinction events and recoveries,” said co-author Randall Irmis at the Natural History Museum of Utah, according to the release.
The team believes that it took millions of years for enough species to build up and restore the food web to stability, both on land and in the oceans. They looked at data from previous research on carbon isotopes from that period to understand the carbon cycle as a measure of stability.
“It really is the same pattern [with land-based ecosystems as marine environments],” Whiteside said, adding that the same seems to hold true for plants.
The researchers say there is no physical evidence that environmental factors, such as ongoing volcanism, slowed down the recovery of ecosystems after the extinction event.
“Comparison with previous food-web modeling studies suggests this low diversity and prevalence of just a few taxa meant that links in the food web were few, causing instability in the ecosystem and making it susceptible to boom-bust cycles and further extinction,” Whiteside said.
“These results are consistent with the idea that the fluctuating carbon cycle reflects the unstable ecosystems in the aftermath of the extinction event.”
The findings were published in the journal Proceedings of the Royal Society B.
A small number of genera, known as “disaster taxa,” survived the mass extinction, and ecosystems are believed to have taken up to eight million years to recover.
The researchers looked at almost 8,600 fossils, originating from Russia and South Africa, from the late Permian to the middle Triassic about 260 million to 242 million years ago.
Based on their analysis, approximately 78 percent of land-based vertebrates appear to have gone extinct. Among the survivors was the taxon Lystrosaurus, comprising reptiles about the size of a large dog, which was scarce before the extinction event, but abundant in the Triassic.
Procolophonids were another group of reptiles that showed a similar pattern of rarity and then dominance.
“It means the (terrestrial ecosystems) were more subject to greater risk of collapse because there were fewer links [in the food web],” said study co-author Jessica Whiteside at Brown University in a press release.
The researchers propose that boom-and-bust cycles followed the mass extinctions like “mini-extinction events and recoveries,” said co-author Randall Irmis at the Natural History Museum of Utah, according to the release.
The team believes that it took millions of years for enough species to build up and restore the food web to stability, both on land and in the oceans. They looked at data from previous research on carbon isotopes from that period to understand the carbon cycle as a measure of stability.
“It really is the same pattern [with land-based ecosystems as marine environments],” Whiteside said, adding that the same seems to hold true for plants.
The researchers say there is no physical evidence that environmental factors, such as ongoing volcanism, slowed down the recovery of ecosystems after the extinction event.
“Comparison with previous food-web modeling studies suggests this low diversity and prevalence of just a few taxa meant that links in the food web were few, causing instability in the ecosystem and making it susceptible to boom-bust cycles and further extinction,” Whiteside said.
“These results are consistent with the idea that the fluctuating carbon cycle reflects the unstable ecosystems in the aftermath of the extinction event.”
The findings were published in the journal Proceedings of the Royal Society B.
