The discovery of fossils of starfish, sea urchins and snails more than 180 million years old in the Austrian Alps suggest deep oceans played a much bigger role in protecting marine biodiversity than thought.
According to new research, a number of animals evolved in the deep sea before spreading to shallow waters, overturning the widely held belief that deep-sea animals evolved from their shallow water ancestors.
The research by Professor Andy Gale, of the University of Portsmouth, and colleagues in Germany is published in the journal Proceedings of The Royal Society B.
Professor Gale said: “Until now, very little was known about the geological history of deep-sea communities. These findings are controversial, because it has been widely believed that brief but intense periods of oxygen deprivation and warming caused periodic mass extinction of deep sea animals. Our findings contradict this.
“The research sheds light on sea creatures which lived so deep in the ocean that sunlight never reached them. It appears that darkness and depth protected them and played a much greater role in protecting modern deep-sea biodiversity than previously thought.”
The findings also suggest that the deep sea was more successful in sheltering animals against extinction than shallow coastal seas, and that deep sea species might be more resilient to extinction than their shallow water cousins.
The researchers are now calling for a “careful reappraisal” of the impact on marine life of deep-sea trawling and mining.
Professor Gale, from the University’s School of Earth and Environmental Sciences, and colleagues from the Luxembourg Natural History Museum report the discovery of at least 68 different species of echinoderms, molluscs, brachiopods and crustaceans in their research after examining fossils in the Austrian Alps near Salzburg.
Professor Gale said: “The evolutionary processes which shaped the deep-sea are still considered controversial in the scientific world because so little is known about them. However, these new findings provide a unique window into Early Jurassic deep-sea biodiversity.
“It seems that once families of some species had colonised the deep sea, they either remained there or became extinct. Occurrences in shallow water of these same families suggests they have sometimes temporarily expanded into shallow waters.”