WELLINGTON, March 4 (Xinhua) -- Russian and New Zealand scientists are working together to find the cause of the Earth's biggest ever mass extinction, which wiped out 96 percent of marine species and 70 percent inland animals in an unknown event 252 million years ago.
Two scientists from the Far East branch of the Russian Academy of Sciences had arrived in New Zealand to study what is claimed to be the Southern Hemisphere's best collection of fossilized bivalves clams and mussels for clues to the cause of the Permian-Triassic extinction event, New Zealand's Institute of Geological and Nuclear Sciences (GNS Science) said Tuesday.
Bivalve molluscs rose to prominence as a hugely successful group of marine organisms in the Permian era, and limestone formations in the South Island up to 500 meters thick were comprised almost entirely of shell remains of mussels known as Atomodesma, said a statement from GNS Science.
The Russian scientists would compare the New Zealand fossils with Russian collections found in similar Permian limestone formations.
"What's amazing is that we have many genera in common with Russia, which underlines the fact that they were a dominant bipolar group of clams in the Permian era," GNS senior paleontologist Hamish Campbell said in the statement.
Distinctive Permian bivalves, including Atomodesma, became extinct in the Permian-Triassic extinction event, but the cause of the mass extinction remained uncertain.
Scientists had been exploring the possibility of a volcanic event, but lacked convincing evidence.
An extra-terrestrial cause seemed more probable, but a meteorite appeared unlikely and a comet strike was difficult to prove.
The Russian scientists would collect New Zealand Permian rocks and fossils to take back to Russia for comparative research and further collaboration.