An incoming mass extinction isn’t as hard to spot as we’d believed, new research suggests.
Paleobiologists from the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) say that the build-up to the largest mass extinction event ever recorded was a lot less inconspicuous than anyone assumed. Armed with this knowledge, they also make a worrying remark: some of the tell-tale signs are unfolding today.
Mass extinctions are like really deep economic crises, but for life — which is why such events are also referred to as ‘biotic crises’. They’re rare, dramatic events, reaping life with terrifying efficiency: the ‘tamest’ mass extinctions cull around 70% to 75% of all species. The largest such event we know of, the Permian-Triassic extinction event, claimed an estimated 83% of all genera and 90% to 96% of all species. Such is their effect that geologists actually use these events as separators between whole geological eras.
Draw of the curtain
Needless to say, such events completely alter the course of evolution, usually on a planetary scale. The Permian-Triassic event made the rise of the dinosaurs possible, and a subsequent mass extinction 65 million years ago threw them off their throne — allowing mammals, and ultimately humans, to move in. There have been five such events that we know of so far.
Given their sheer ability to stir things up — especially for the dominant species (used to be dinosaurs, now it’s us) — mass extinction events are certainly something we’d want to avoid. Thus making the fact that a sixth one is likely incoming a very, very scary prospect. However, a new paper suggests that our view of how these events unfold don’t necessarily correspond to reality.
It’s widely believed that they start relatively abruptly and unfold quickly (in geological terms); most estimates of the Cretaceous-Paleogene extinction, the one with the meteorite that wiped out the dinosaurs, pin its duration around the 60,000-year mark.
The new paper, published by researchers from Germany and Iran, suggests that this crisis unfolded over a longer period of time. Led by Prof. Dr. Wolfgang Kießling, Chair for Palaeoenvironmental Research at FAU, the team examined fossils from largely unresearched geological profiles in Iran. According to their findings, the first indicators of a mass extinction became apparent as early as 700,000 years prior to the event itself — several species of ammonoids disappeared around that time, and the remaining species became increasingly smaller and less complex closer to the extinction event.
“There is much evidence of severe global warming, ocean acidification and a lack of oxygen [today],” says Kießling. “What separates us from the events of the past is the extent of these phenomena. For example, today’s increase in temperature is significantly lower than 250 million years ago”.
The team further reports that some of the processes they observed towards the end of the Permian Period (close to the extinction event) can also be seen today. Most notably, they point to the “increased rate of extinction in all habitats” that can be linked directly to human activity “such as the destruction of habitat, over-fishing, and pollution”. Another worrying sign is the “dwarfing” of ocean species, which they note is “clearly attributed to climate change”.
“We should take these signs very seriously,” he adds.
And I daresay he’s right.
The paper “Pre–mass extinction decline of latest Permian ammonoids” has been published in the journal Geology.