{"id":62458,"date":"2021-04-19T15:01:09","date_gmt":"2021-04-19T19:01:09","guid":{"rendered":"https:\/\/naturalsciences.org\/calendar\/?post_type=news&p=62458"},"modified":"2021-04-19T15:01:09","modified_gmt":"2021-04-19T19:01:09","slug":"earths-biggest-mass-extinction-lasted-much-longer-on-land-than-in-the-sea","status":"publish","type":"news","link":"https:\/\/naturalsciences.org\/calendar\/news\/earths-biggest-mass-extinction-lasted-much-longer-on-land-than-in-the-sea\/","title":{"rendered":"Earth\u2019s biggest mass extinction lasted much longer on land than in the sea"},"content":{"rendered":"

\"Illustration<\/p>\n

Illustration of the Karoo Basin during the mass extinction at the end of the Permian, some 252 million years ago. The protomammal Lystrosaurus<\/em> shown in the foreground. Lystrosaurus<\/em> is what paleontologists call a \u201cdisaster taxon\u201d \u2014 a group that thrived during a time when most other life was struggling. Illustration: Gina Viglietti.<\/div>\n
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Our planet\u2019s worst mass extinction event happened 252 million years ago, when massive volcanic eruptions caused catastrophic climate change. The vast majority of animal species went extinct, and by the time the dust settled the planet had entered the early days of the Age of Dinosaurs. Scientists are still learning about the patterns of which animals went extinct and which ones survived and why. In a new study in PNAS<\/em>, researchers found that while extinctions happened rapidly in the oceans, life on land underwent a longer, more drawn-out period of extinctions.<\/p>\n

\u201cPeople assumed that because the marine extinction happened over a short period of time, life on land should have followed the same pattern, but we found that the marine extinction may actually be a punctuation to a longer, more drawn-out event on land,\u201d says Pia Viglietti, a postdoctoral researcher at Chicago\u2019s Field Museum and the lead author of the PNAS <\/em>study.<\/p>\n

Part of why scientists had looked to the marine extinctions for clues as to what happened on land is that there\u2019s a more complete fossil record of life underwater. If you want to become a fossil, dying in the water, where your body will rapidly get covered by sediment, is a good way to make that happen. As a result, paleontologists have known for a while that 252 million years ago a mass extinction hit at the end of the Permian period, and within 100,000 years, more than 85% of the species living in the ocean went extinct.<\/p>\n

\u201cAs the most devastating event in the history of life on Earth, the end-Permian extinction has attracted a lot of research interest, but much of that has been focused on the marine record. Its effects on terrestrial \u2014 that is, land-based \u2014 ecosystems are relatively poorly understood, in large part because there are so few fossil-bearing regions worldwide yielding terrestrial fossils of the right age,\u201d says Christian Kammerer, one of the co-authors on the paper and Research Curator of Paleontology at the North Carolina Museum of Natural Sciences in Raleigh.<\/p>\n

\"BethulieBethulie Canyon, Free State Province is a well-known collecting site of fossils from the Permo-Triassic Period within South Africa\u2019s Karoo Basin. Photo: Pia Viglietti.<\/span><\/p>\n

To learn what happened to life on land, Viglietti, Kammerer and their colleagues examined fossils from hundreds of fossil animals that lived in what\u2019s now South Africa\u2019s Karoo Basin at the time of the mass extinction. The researchers created a database and separated the fossils by age, grouping together specimens by 300,000-year time intervals. This approach allowed the researchers to quantify the appearance and disappearance of different species and look at the bigger picture of life over time, rather than just relying on individual specimens to tell the whole story. Kammerer notes, \u201cThe Karoo record is remarkably complete, by far the best in the world for looking at the end-Permian extinction on land, and we have been able to assemble a data set of unprecedented scale and precision to examine the dynamics of this extinction in fine detail.\u201d<\/p>\n

\"ZaitunaZaituna Skosan, Collections Manager at Iziko Museum in Cape Town, South Africa, glues together a broken-up fossil during fieldwork in the Karoo Basin. Photo: Roger Smith.<\/span><\/p>\n

\u201cOur approach unifies the data and says, okay, within this time bin we have these species, but as we go up, we have these other species,\u201d adds Viglietti. \u201cBy applying sampling methods to these bins, we can help correct for issues like having more or fewer specimens collected in different time intervals or places. Ultimately, it lets us quantify how much extinction is happening and how quickly new species are appearing.\u201d<\/p>\n

\"Excavating<\/div>\n

RIGHT: A fossil of the dicynodont Lystrosaurus<\/em>, a mammal relative that survives the end-Permian mass extinction event, is collected during fieldwork in South Africa\u2019s Karoo Basin. Photo: Roger Smith.<\/p>\n

One of the species that helped reveal patterns of extinction and recovery was Lystrosaurus<\/em>, an herbivorous early mammal relative that ranged from the size of a small dog to a cow, depending on the species. \u201cIt had a beak and tusks, it wasn\u2019t the most attractive animal, but I have a soft spot for Lystrosaurus <\/em>because it was like the first animal I studied as a grad student, so coming full circle with Lystrosaurus <\/em>in this study made me quite happy,\u201d says Viglietti.<\/p>\n

Lystrosaurus <\/em>is what paleontologists call a \u201cdisaster taxon\u201d \u2014 a group that thrived during a time when most other life was struggling. \u201cLystrosaurus <\/em>is like a poster child for the end-Permian extinction that\u2019s always been portrayed as this animal that flourishes in the aftermath of all this extinction and just takes over,\u201d says Viglietti. \u201cBut we see Lystrosaurus <\/em>appearing before the extinction even got started; it was already abundant. It got us thinking about what was driving that abundance \u2014 if Lystrosaurus <\/em>just took over the barren landscape after other animals went extinct, or if the environment was changing and Lystrosaurus <\/em>adapted to these changes that were causing extinction for all these other species. Our best guess is the latter.\u201d<\/p>\n

Examining fossils like Lystrosaurus <\/em>showed the researchers that the end-Permian extinction looked very different on land than it did in the oceans \u2014 it was a much longer, more drawn-out affair. If the history of life on Earth were compressed into a single year and the end-Permian extinction killed 95% of the ocean\u2019s animals in a matter of 14 minutes, the land extinction would have taken 10 times as long, about 2 hours and 20 minutes.<\/p>\n

It\u2019s not clear exactly why the mass extinction event happened so much more slowly on land. \u201cThe changes to the Earth\u2019s climate were cumulative and added up over time. Ecosystems were slowly disrupted, and then it just got to a point where everything collapsed, like the straw that breaks the camel\u2019s back,\u201d says Viglietti. \u201cEverything\u2019s fine, until it\u2019s not.\u201d<\/p>\n

One reason for the discrepancy could be that the oceans can absorb chemical changes and stabilize themselves, up to a point. \u201cIn today\u2019s climate crisis, the oceans can absorb a lot of carbon dioxide or rise in temperature without people realizing, and then all of a sudden you get sudden ecosystem breakdowns like ocean acidification and coral bleaching,\u201d says Viglietti. The same might be true for the late Permian oceans.<\/p>\n

Understanding what happened in the end-Permian mass extinction gives us clues about the rise of the dinosaurs \u2014 many of the ancient mammal relatives went extinct, leaving ecological vacancies that dinosaur ancestors evolved to fill. But the end-Permian extinction also provides insights into the mass extinction event that the Earth is currently undergoing due to climate change and habitat destruction.<\/p>\n

\u201cThe environmental changes that we are causing and the impacts we are having on animal and plant species are getting to the point where the scale is such that there isn\u2019t really anything in human history that is comparable,\u201d says the Field Museum\u2019s Kenneth Angielczyk, senior author on the paper. \u201cThe fossil record can give us some idea of what massive biodiversity crises are like and how they proceed.\u201d<\/p>\n

\u201cIt takes a long time to recover from extinction. When we lose diversity, it\u2019s not going to recover in our lifetime, it\u2019s going to take hundreds of thousands of years, or even millions,\u201d says Viglietti. \u201cStudies like this one show what our society should be focusing on.\u201d<\/p>\n

\"SkullSkull of one of the large predators that died out in the end-Permian mass extinction.<\/span><\/p>\n","protected":false},"author":2,"featured_media":62464,"menu_order":0,"template":"","format":"standard","meta":{"_links_to":"","_links_to_target":""},"acf":[],"_links":{"self":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/news\/62458"}],"collection":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/news"}],"about":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/types\/news"}],"author":[{"embeddable":true,"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/users\/2"}],"version-history":[{"count":0,"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/news\/62458\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/media\/62464"}],"wp:attachment":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/media?parent=62458"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}