A new study suggests that the same asteroid that killed the dinosaurs a long time ago might have also wiped out the ancient molluscs.
An earlier study suggests that ocean acidification triggered by volcanic eruptions wiped out 90 percent of the ancient marine species some 252 million years ago. However, the ammonites, coincidentally, disappeared along with the dinosaurs when the asteroid hit Earth. The ammonites are the extinct group of molluscs that are related to the existing coleoids such as the octopus, squid, and cuttlefish.
Researchers at the University of Southampton set out to determine whether the extinction of the molluscs was caused by the asteroid impact or the ocean acidification. They created different simulations using other environmental causes of ocean acidification such as the wildfires that emit carbon dioxide into the atmosphere and the vaporization of the gypsum rocks that causes acid rain.
The simulations showed that the acidification levels produced by the wildfires and the gypsum rocks weren't strong enough to affect the ammonites.
Based on their findings, the researchers settled that ocean acidification wasn't the main driver of extinction of the ancient molluscs.
"While the consequences of the various impact mechanisms could have made the surface ocean more acidic, our results do not point to enough ocean acidification to cause global extinctions. Out of several factors we considered in our model simulation, only one (sulphuric acid) could have made the surface ocean severely corrosive to calcite, but even then the amounts of sulphur required are unfeasibly large," Professor Toby Tyrrell, from Ocean and Earth Science at the University of Southampton and co-author of the study, said in a press release.
The researchers said that the possible cause could be the prolonged darkness because of the soot and aerosols deposited the atmosphere after the asteroid impact. However, this notion is yet to be explored.
The study was published in the May 11 issue of the Proceedings of the National Academy of Sciences (PNAS).
