{"id":1284,"date":"2022-11-21T09:20:23","date_gmt":"2022-11-21T14:20:23","guid":{"rendered":"https:\/\/techfragments.com\/?p=1284"},"modified":"2022-11-21T09:20:24","modified_gmt":"2022-11-21T14:20:24","slug":"sea-oxygen-late-ordovician-extinction","status":"publish","type":"post","link":"https:\/\/techfragments.com\/sea-oxygen-late-ordovician-extinction\/","title":{"rendered":"Did Sea Oxygen Levels Play Role In Earth’s First Mass Extinction?"},"content":{"rendered":"

According to a recent study led by Florida State University scientists, the first mass extinction on Earth may have been caused by abrupt changes in marine oxygen levels.<\/p>\n

The Late Ordovician mass extinction, or LOME, which wiped out about 85% of marine species, occurred 443 million years ago. Scientists have long studied this mass extinction and are still looking into possible causes, such as reduced habitat loss in a rapidly cooling world or persistently low-oxygen conditions in the oceans.<\/p>\n

Graptolites<\/a> and brachiopods<\/a> are two examples of groups of organisms that started to decline very early during this mass extinction interval, but paleontologists didn’t really have any solid evidence of an environmental or climate signature to link that early decline of these groups to a specific mechanism.<\/p>\n

“This paper can directly link that early phase of extinction to changes in oxygen. We see a marked change in thallium isotopes at the same time these organisms start their steady decline into the main phase of the mass extinction event,”<\/p><\/blockquote>\n

said co-author Seth Young, an associate professor in Florida State’s Department of Earth, Ocean and Atmospheric Science.<\/p>\n

Icehouse Environment<\/h2>\n
\"Ordovician

Ordovician flora and fauna as shown in a diorama at the US National Museum of Natural History. Credit: Fritz Geller-Grimm CC-BY<\/p><\/div>\n

The oxygen level dropped and was immediately followed by a rise. This sudden change in oxygen occurred simultaneously with the traditional first die-off of a mass extinction and a significant expansion of the ice sheet over the former South Pole.<\/p>\n

“Turbulence in oxygen levels in oceanic waters is really what seems to have been pretty problematic for organisms that were living in the Late Ordovician at that time, which might have been adapted to cope with low oxygen conditions initially or vice versa,”<\/p><\/blockquote>\n

Young said.<\/p>\n

One of the five significant mass extinctions in Earth’s history, the Late Ordovician extinction is the only one that experts are certain occurred in an environment known as an “icehouse” where ice sheets cover much of the planet’s surface.<\/p>\n

Earth is currently experiencing icehouse conditions and biodiversity loss, making this ancient mass extinction an important analog for current conditions, as well as attempting to understand Earth’s future as our climate warms<\/a> and ice sheets recede.<\/p>\n

Low Oxygen Levels<\/h2>\n

Previous studies of the environment around the Late Ordovician mass extinction used evidence from places with more oxygen. This study, on the other hand, used shales that were laid down in deeper water with less oxygen. These shales have different geochemical signatures, so the researchers were able to draw conclusions about global marine conditions rather than local ones.<\/p>\n

“The discovery of the initial expansion of\u00a0low-oxygen conditions\u00a0on a global level and the coincidence with the early phases of decline in marine animals helps paint a clearer picture of what was happening with this\u00a0extinction\u00a0event,”<\/p><\/blockquote>\n

said lead author Nevin Kozik.<\/p>\n

The other big five mass extinctions are:<\/p>\n