Worrying on behalf of the Sixth Great Extinction, Patrick Monahan at Science:
… That’s why Roy Plotnick, a paleontologist at the University of Illinois, Chicago, and lead author of the study, thinks about far-flung scenarios involving future paleontologists. “We really need to look at modern day extinctions as if they were in the fossil record already, in order to make a comparison,” he says. So he and his colleagues searched fossil databases for modern mammal species—both those threatened by extinction and those that aren’t—to see how many modern extinctions would be detectable by relying only on fossils.
Humans have recorded fossils for just 9% of the world’s threatened modern mammal species, the team reports this month in Ecology Letters. Nonthreatened mammals are twice as likely to show up in fossil databases at about 20%. That bias may distort our understanding of ancient extinctions, Plotnick says—the species that are most likely to go extinct also appear to be the ones who rarely leave behind a trace. One possible reason for this bias, the team found, is that smaller species are less likely to wind up in the fossil record, as are those with smaller ranges. Tiny species are less likely to make it through the sedimentary processes that turn remains into fossils—and species with small ranges are less likely to live in the places where those processes happen. Extinctions of those species would then be missing from the fossil record, making future paleontologists underestimate the number of extinctions that are occurring now. More.
But how do we know if/when they are extinct? It would help if the concept of “speciation” weren’t such a mess. Without it, how do we define extinction?
Is there is fact a Sixth Great Extinction going on? To what extent is it an artifact of this problem?
Is the Sixth Great Extinction a big myth? (Vincent Torley)
“Speciation” means what exactly? No one can define it but it is the basis of Darwinian evolution.
Some aren’t even gone actually. Species assumed to be extinct sometimes turn up again
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