Washington, Oct 30: The biggest mass extinction during the Cretaceous Period 65 million years ago that wiped out the dinosaurs along with other species, holds stark lessons for the modern world, according to a study.
The structure of North American ecosystems made the extinction worse than it might have been, said the study conducted by researchers from the University of Chicago, the California Academy of Sciences and the Field Museum of Natural History.
The mountain-sized asteroid that left the now-buried Chicxulub impact crater on the coast of Mexico's Yucatan peninsula is almost certainly the ultimate cause of the end-Cretaceous mass extinction, which occurred 65 million years ago, the journal Proceedings of the National Academy of Sciences reported.
Nevertheless, “Our study suggests that the severity of the mass extinction in North America was greater because of the ecological structure of communities at the time,” said Jonathan Mitchell, doctoral student of University of Chicago's Committee on Evolutionary Biology, who led the study.
Mitchell and co-authors Peter Roopnarine of the California Academy and Kenneth Angielczyk of the Field Museum, reconstructed terrestrial food webs for 17 Cretaceous ecological communities.
Seven of these food webs existed within two million years of the Chicxulub impact and 10 came from the preceding 13 million years, according to a Chicago statement.
“Besides shedding light on this ancient extinction, our findings imply that seemingly innocuous changes to ecosystems caused by humans might reduce the ecosystems' abilities to withstand unexpected disturbances,” Roopnarine said.
The findings are based on a computer model showing how disturbances spread through the food web.
Roopnarine developed the simulation to predict how many animal species would become extinct from a plant die-off, a likely consequence of the impact.
“Our analyses show that more species became extinct for a given plant die-off in the youngest communities,” Mitchell said.
“We can trace this difference in response to changes in a number of key ecological groups such as plant-eating dinosaurs like Triceratops and small mammals.”
In one run, T. Rex might eat only Triceratops, while in another it eats only duck-billed dinosaurs, and in a third it might eat a more varied diet.
This stems from the uncertainty regarding exactly what Cretaceous animals ate, but this uncertainty actually worked to the study's benefit.
