LOS ANGELES, CA (Catholic Online) - Some scientists claim that more than 65 million years ago, a huge asteroid plunged into the earth in Mexico. Many species became extinct, including the dinosaurs, thus ending the Cretaceous Period of Earth history.

The food chain at that time was already under tremendous strain before the collision. The ecosystem simply could not cope with the cataclysm, and plant life died off.

Therefore, the continuous exploitation of the Earth's resources could place humankind in the same peril as we stress the planet with mono-crops and hasten the extinction animals, plant life and marine species.

The impact zone of the now-buried Chicxulub crater on the coast of Mexico's Yucatan Peninsula had widespread effect on the world's ecology.

These scientists examined a computer model in order to see what happened up and down the food chain. They found the structure of North American ecosystems made the extinction much worse than it might have been.

"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," Jonathan Mitchell of Chicago's Committee on Evolutionary Biology says.

Reconstructing terrestrial food webs for 17 Cretaceous ecological communities, seven of these food webs existed within two million years of the Chicxulub impact. Ten had come from the preceding 13 million years.

The computer model showed how disturbances spread through the food web and developed the simulation to predict how many animal species would become extinct from a plant die-off.

"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."

Environmental and biological factors meant food webs were already under strain before the asteroid hit. A large scale disturbance was more likely to have an effect on the survival of species.

"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," Mitchell says.

"It is therefore critical that conservation efforts pay attention to ecosystem functioning and the roles of species in their communities as we continue to degrade our modern ecosystems."

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