investigator studying malformed plankton in the fossil record have revealed that one of the oldest mass extinction in the history of life sentence on Earth may have been spark by O depletion and the increasing presence of harmful metals in the oceans . The findings are published inNature Communicationsthis hebdomad .
Life was thriving in the sea during the Ordovician Period ( more than 440 million year ago ) , until theOrdovician - Silurian experimental extinction eventseliminated an estimated 85 percent of all Ordovician specie . These events were thought to have take place in pulses that correspond to glacial episodes of cooler climes and shrinking habitats . However , late studies have begun to implicate the spread of anoxia ( or scummy oxygen ) in the sea as an additional take force of mass extinction .
To study the effects of paleo - pollution in marine environments , an international squad led by Ghent University’sThijs Vandenbrouckeexamined the geochemical signals of fossil plankton living in what ’s now the Libyan desert during the trigger of a late Silurian ( or mid - Pridoli ) extinction effect . They focused on chitinozoans : 100 - 500 micrometer gauge microfossils that represent fossil ballock example of zooplankton that lived in shallow ocean layer . ( The soft - bodied parent are n’t typically preserve in the fossil disk . )
Aberrations in chitinozoans were found to coincide with a striking increment of metals – including iron , lead , manganese , and arsenic – in both the fogy specimen and the rocks they were preserved in .
The abnormal growth of advanced being living with eminent level of metal toxins are well documented . In fact , misshapen plankton , arthropods , and fish are routinely used as a forensic tool for discover contaminant in bodies of water . Metal poisoning , the squad concludes , may very well have cause the ancient malformations . gamy level of these harmful metals suggest changes in ocean alchemy . Together with the spread of anoxia , these factors may have been a kick in “ kill mechanism , ” making deformed plankton forerunner of mass extinction .
