14.2 C
London
Sunday, June 20, 2021

Update COVID-19 03 November 2020

03 November 2020 — Seven (7) new COVID-19 cases were identified out of 1604 samples tested today. This brings the cumulative number of confirmed cases to five thousand, one hundred, and sixty-two (5162). To date, four thousand, nine hundred, and thirty (4930) patients have recovered, including eight (8) in the past 24 hours. The number…
More

    Latest Posts

    This Week in Apps: Spotify debuts a Clubhouse rival, Facebook tests Audio Rooms in US, Amazon cuts Appstore commissions

    Welcome back to This Week in Apps, the weekly TechCrunch series that recaps the latest in mobile OS news, mobile applications and the overall app economy. The app industry continues to grow, with a record 218 billion downloads and $143 billion in global consumer spend in 2020. Consumers last year also spent 3.5 trillion minutes using apps on Android devices…

    Investors say Eindhoven poised to become Netherlands’ No. 2 tech hub

    Eindhoven might not immediately spring to mind as a high-tech hub, but the Netherlands city is keen to position itself as a center for deep tech in Europe. The Technical University of Eindhoven, High Tech Campus Eindhoven, and locally based corporates like ASML and Philips have been eyeing initiatives across Europe and applying what they’ve…

    Daily Crunch: Spotify and Ford make acquisitions

    To get a roundup of TechCrunch’s biggest and most important stories delivered to your inbox every day at 3 p.m. PDT, subscribe here. Welcome back to the Daily Crunch for Friday, June 18. Congratulations! You’ve made it to the end of the week without Alexander, who will return bright-eyed on Monday. TechCrunch has the day…

    Extra Crunch roundup: influencer marketing 101, spotting future unicorns, Apple AirTags teardown

    With the right message, even a small startup can connect with established and emerging stars on TikTok, Instagram and YouTube who will promote your products and services — as long as your marketing team understands the influencer marketplace. Creators have a wide variety of brands and revenue channels to choose from, but marketers who understand…

    Mystery event caused shark populations to crash 19 million years ago

    Fossil records show that roughly 90 percent of the planet’s open-ocean sharks inexplicably vanished.

    Published June 3, 2021

    9 min read

    Sharks are some of nature’s greatest survivors. For more than 400 million years, the marine predators have plied Earth’s waters, from shallow reefs to the heart of the open ocean. Sharks are older than the oldest fossil forest. They’ve made it through at least four mass extinctions.

    And yet, 19 million years ago, something mysteriously dealt open-ocean sharks a huge blow—one from which they’ve never recovered.

    Records of this extinction, detailed for the first time in the journal Science, come in the form of shark scales, called denticles, found in seafloor samples from the Pacific Ocean. Based on the shapes and abundance of denticles in the samples, the researchers estimate that the planet’s open-ocean shark populations suddenly and inexplicably fell by more than 90 percent. By contrast, during the extinction event that killed off the non-avian dinosaurs 66 million years ago, sharks suffered losses of roughly 30 percent.

    “The sharks are screaming, Something really big happened here,” says lead study author Elizabeth Sibert, a paleobiologist and oceanographer at Yale University. “Sharks have a 400-million-year evolutionary history; they’ve been around a long time; they’ve seen a lot. And there’s something that could knock out 90 percent of them?”

    Nobody knows what triggered the extinction, but whatever occurred, it must have happened in roughly 100,000 years, the geological blink of an eye. Bizarrely, the extinction doesn’t align with any known major shift in Earth’s climate or any major evolutionary change among other open-ocean predators.

    That said, the decline in sharks may have given other marine animals their chance to shine. Several million years after the extinction, groups including tuna, seabirds, whales, and migratory sharks diversified, locking in the kind of open-ocean ecosystem we see today.

    Researchers also caution that the findings may bode ill for modern shark populations. Since 1970, the total number of oceanic sharks and rays has fallen by 71 percent, according to a recent study published in Nature, a decline brought on by overfishing. If open-ocean sharks could take an existential wallop 19 million years ago and never fully recover, what will future oceans look like because of human activity?

    “In a way, it does show clearly how fragile these top predators—these charismatic animals—are to any sort of sudden environmental change,” says shark paleobiologist Mohamad Bazzi, a Ph.D. candidate at Uppsala University in Sweden who wasn’t involved with the study. “It has tremendous implications today.”

    Shark library

    Sibert first stumbled across hints of this mystery extinction several years ago, while she was trying to understand the broad patterns of how fish—including sharks—lived in the open ocean over the last 85 million years of Earth’s history.

    To uncover these big-picture trends, Sibert sought out one of Earth’s most important libraries: deep-sea sediment cores that scientists have been drilling since 1968. In essence, the seafloor acts as a history book the size of a planet. Chemical and fossil clues in each sediment layer inscribe the history of how Earth has changed over time, as well as how life responded. For example, these records have been critical to reconstructing past changes in Earth’s climate.

    Sibert’s focus was on a more obscure component of the cores: “ichthyoliths,” tiny fish-derived fossils that include fish teeth and shark denticles, which the animals constantly shed and replace in life. By tracking the types and overall amounts of these fossils through the cores’ many layers, Sibert hoped to track changes in ocean ecosystems over long periods of Earth’s recent history.

    To ensure that she got a good sense of global patterns, as opposed to local or regional ones, Sibert relied on two sediment cores that had been drilled from the Pacific Ocean’s subtropical gyres, vast swirling currents that have remained stable for tens of millions of years, and where any given spot on the seafloor might contain denticles and teeth from animals that lived hundreds to thousands of miles away. This kind of science requires the investment of generations. The main core Sibert focused on had been collected in the South Pacific in 1983, before Sibert was born.

    When Sibert counted the shark scales and fish teeth, she found that the open ocean shifted gears several times over the past 85 million years. Up until the dinosaur-killing extinction 66 million years ago, sediments contained about one shark denticle for every fish tooth. By a couple million years later, the proportion of shark denticles had fallen by half.

    By roughly 56 million years ago, the ratio had stabilized to one shark denticle for every five fish teeth. That ratio stayed rock-solid for the next 40 million years or so—until 19 million years ago, when she could find only one denticle for every 100 fish teeth.

    “There’s no way to unsee it,” she says.

    The devil’s in the denticles

    Sibert published these observations in the journal Proceedings of the Royal Society B in 2016, but there was still a lot she didn’t know. Did the collapse hit all types of sharks equally? Or did some types of scales—and, by extension, types of sharks—go completely extinct 19 million years ago?

    To find out, Sibert teamed up with a dedicated student, Leah Rubin, who was then an undergraduate student at the College of the Atlantic in Bar Harbor, Maine. After looking at nearly 600 pictures of modern shark, skate, and ray skin, and nearly 1,300 fossils, Rubin figured out how to classify the sediments’ fossil denticles based on features such as their shapes and ridges.

    “They’re too small to be seen with the naked eye to any detail … You can’t really get a feeling for how gorgeous and intricate they are,” says Rubin, who is now starting a Ph.D. at SUNY ESF in Syracuse, New York.

    Once Rubin and Sibert classified the denticles, their results were shocking. Samples less than 19 million years old had just 30 percent the denticle types that older sediments had. Something, somehow, had wiped out many, if not most, of the Pacific’s open-ocean shark species.

    What’s more, the extinction appears to have hit some groups harder than others. So-called geometric denticles, which tend to belong to slower-swimming sharks among modern species, collapsed at 19 million years, while other scale types persisted.

    Spotty records

    The discovery will no doubt spark renewed interest in this time period, known in scientific circles as the Early Miocene sub-epoch. Existing climate records from the time suggest that Earth’s climate was stable then, but it’s also poorly understood.

    According to Sibert, of the 683 deep-sea sediment cores that go deep enough to cover the Early Miocene, more than 80 percent are missing sediments from that time period, for reasons that remain unclear. But between the clear fossil evidence and Earth’s spotty record-keeping, it’s entirely possible that some kind of short-term climate event struck Earth 19 million years ago.

    “Some aspects of [ancient Earth’s] study are still so young that you can make enormous discoveries about things that happened relatively recently,” says James Rae, a climate scientist at the University of St. Andrews in Scotland who wasn’t involved with the study.

    In the 1980s, researchers noticed that deep-sea sediments showed that marine plankton went through a major extinction about 55 million years ago. Later evidence revealed that at that time, carbon dioxide levels rose rapidly, causing temperatures to rise and Earth’s oceans to acidify.

    Geologists now closely study this period, which is called the Paleocene-Eocene Thermal Maximum, to learn more about how Earth might respond to human-caused climate change. Perhaps future scientists will study the Miocene shark extinction in the same way—but only more data will solve the mystery.

    “There’s gotta be something there,” Sibert says. “We just don’t know what it is yet.”

    Latest Posts

    This Week in Apps: Spotify debuts a Clubhouse rival, Facebook tests Audio Rooms in US, Amazon cuts Appstore commissions

    Welcome back to This Week in Apps, the weekly TechCrunch series that recaps the latest in mobile OS news, mobile applications and the overall app economy. The app industry continues to grow, with a record 218 billion downloads and $143 billion in global consumer spend in 2020. Consumers last year also spent 3.5 trillion minutes using apps on Android devices…

    Investors say Eindhoven poised to become Netherlands’ No. 2 tech hub

    Eindhoven might not immediately spring to mind as a high-tech hub, but the Netherlands city is keen to position itself as a center for deep tech in Europe. The Technical University of Eindhoven, High Tech Campus Eindhoven, and locally based corporates like ASML and Philips have been eyeing initiatives across Europe and applying what they’ve…

    Daily Crunch: Spotify and Ford make acquisitions

    To get a roundup of TechCrunch’s biggest and most important stories delivered to your inbox every day at 3 p.m. PDT, subscribe here. Welcome back to the Daily Crunch for Friday, June 18. Congratulations! You’ve made it to the end of the week without Alexander, who will return bright-eyed on Monday. TechCrunch has the day…

    Extra Crunch roundup: influencer marketing 101, spotting future unicorns, Apple AirTags teardown

    With the right message, even a small startup can connect with established and emerging stars on TikTok, Instagram and YouTube who will promote your products and services — as long as your marketing team understands the influencer marketplace. Creators have a wide variety of brands and revenue channels to choose from, but marketers who understand…

    Don't Miss

    Temple Mount: Clashes break out between Israeli police, Palestinians

    Nine injuries have so far been reported, and in one video a man could be seen being carried off by Red Crescent volunteers. Temple Mount: Clashes break out between Israeli police, Palestinians Clashes broke out between Border Police and Muslim worshipers at the Temple Mount on Friday, Israel Police said in a statement.Video footage taken…

    Israel to give Palestinians a million vaccines in exchange deal

    The Coordinator of Government Activities in the Territories transferred 100,000 vaccines, within hours of the Israeli government reaching an agreement with the Palestinian Authority.The exchange deal will allow a large number of Palestinians to be vaccinated months earlier than planned.Israel plans to provide the PA with surplus vaccines that will soon expire.When the Palestinian Authority…

    A-G vows to defend IDF soldiers from ICC war crimes probe

    Attorney-General Avichai Mandelblit promised Thursday night a strong defense of IDF soldiers and other citizens should the International Criminal Court seek to try them for alleged war crimes.Speaking at a conference at Bar-Ilan honoring retired district court judge Menachem Finklestein upon the publication of his new book on laws of war, Mandelblit threw down the gauntlet before…

    WATCH: IDF attacks targets in Gaza; Kohavi: Prepare for round of fighting

    The strikes were carried out in response to multiple incendiary balloons launched which led to some eight fires in Israeli communities near Gaza. IDF strikes targets in Gaza, June 18, 2021. (Credit: IDF Spokesperson's Unit) The IDF attacked a number of targets in the Gaza Strip late Thursday night in response to a number of…

    Israel SlutWalk marches in Jerusalem, protests for ‘abandoned’ women

    Hundreds of demonstrators gathered in Jerusalem Friday for the city's annual SlutWalk, a protest against rape culture and violence against women.“We are going back out to the streets, to remind everyone that the public space is ours. That we have a voice. That we are not silent and we are not to blame for the…

    Stay in touch

    To be updated with all the latest news, offers and special announcements.

    × Share your content