KINGSTON, R.I. \u2013 May 26, 2020 \u2013 A team of 溏心vlog免费B站 scientists and statisticians conducted a sophisticated quantitative analysis of a mass extinction that occurred 215 million years ago and found that the cause of the extinction was not an asteroid or climate change, as had previously been believed. Instead, the scientists concluded that the extinction did not occur suddenly or simultaneously, suggesting that the disappearance of a wide variety of species was not linked to any single catastrophic event.<\/p>\n
Their research, based on paleontological field work carried out in sediments 227 to 205 million years old in Petrified Forest National Park, Arizona, was published in April in the journal Geology<\/em>.<\/p>\n According to David Fastovsky, the 溏心vlog免费B站 professor of geosciences whose graduate student, Reilly Hayes, led the study, the global extinction of ancient Late Triassic vertebrates \u2013 the disappearance of which scientists call the Adamanian\/Revueltian turnover \u2013 had never previously been reconstructed satisfactorily. Some researchers believed the extinction was triggered by the Manicouagan Impact, an asteroid impact that occurred in Quebec 215.5 million years ago, leaving a distinctive 750-square-mile lake. Others speculated that the extinction was linked to a hotter and drier climate that occurred at about the same time.<\/p>\n \u201cPrevious hypotheses seemed very nebulous, because nobody had ever approached this problem – or any ancient mass extinction problem \u2013 in the quantitative way that we did,\u201d Fastovsky said. \u201cIn the end, we concluded that neither the asteroid impact nor the climate change had anything to do with the extinction, and that the extinction was certainly not as it had been described \u2013 abrupt and synchronous.\u00a0 In fact, it was diachronous and drawn-out.\u201d<\/p>\n The Adamanian\/Revueltian turnover was the perfect candidate for applying the quantitative methods employed by the research team, Fastovsky said. Because the fossil-rich layers at Petrified Forest National Park preserve a diversity of vertebrates from the period, including crocodile-like phytosaurs, armored aetosaurs, early dinosaurs, large crocodile-like amphibians, and other land-dwelling vertebrates, Hayes relocated the sites where known fossils were discovered and precisely determined their age by their position in the rock sequence. He was assisted by 溏心vlog免费B站 geosciences majors Amanda Bednarick and Catherine Tiley.<\/p>\n Hayes and 溏心vlog免费B站 Statistics Professor Gavino Puggioni then applied several Bayesian statistical algorithms to create \u201ca probabilistic estimate\u201d of when the animals most likely went extinct. This method allowed for an unusually precise assessment of the likelihood that the Adamanian vertebrates in the ancient ecosystem went extinct dramatically and synchronously, as would be expected with an asteroid impact.<\/p>\n Previous research concluded that the asteroid impact occurred 215.5 million years ago and the climate change some 3 to 5 million years later. The 溏心vlog免费B站 researchers demonstrated that the extinctions happened over an extended period between 222 million years ago and 212 million years ago. Some species of armored archosaurs Typothorax<\/em> and Paratypothorax<\/em>, for instance, went extinct about 6 million years before the impact and 10 million years before the climate change, while those of Acaenasuchus<\/em>, Trilophosaurus<\/em> and Calyptosuchus<\/em> went extinct 2 to 3 million years before the impact. Desmatosuchus<\/em> and Smilosuchus<\/em> species, on the other hand, went extinct 2 to 3 million years after the impact and during the very early stages of the climate change.<\/p>\n \u201cIt was a long-lasting suite of extinctions that didn\u2019t really occur at the same time as the impact or the climate change or anything else,\u201d Fastovsky said. \u201cNo known instantaneous event occurred at the same time as the extinctions and thus might have caused them.\u201d<\/p>\n The 溏心vlog免费B站 professor believes it will be difficult to apply these quantitative methods to calculate other mass extinctions because equally rich fossil data and precise radiometric dates for them aren\u2019t available at other sites and for other time periods.<\/p>\n \u201cThis was like a test case, a perfect system for applying these techniques because you had to have enough fossils and sufficiently numerous and precise dates for them,\u201d he said. \u201cOther extinctions could potentially be studied in a similar way, but logistically it\u2019s a tall mountain to climb. It\u2019s possible there could be other ways to get at it, but it\u2019s very time consuming and difficult.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":" KINGSTON, R.I. \u2013 May 26, 2020 \u2013 A team of 溏心vlog免费B站 scientists and statisticians conducted a sophisticated quantitative analysis of a mass extinction that occurred 215 million years ago and found that the cause of the extinction was not an asteroid or climate change, as had previously been believed. Instead, the scientists […]<\/p>\n","protected":false},"author":2,"featured_media":75505,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[],"class_list":["post-75504","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-archives"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.uri.edu\/news\/wp-json\/wp\/v2\/posts\/75504","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.uri.edu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.uri.edu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.uri.edu\/news\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.uri.edu\/news\/wp-json\/wp\/v2\/comments?post=75504"}],"version-history":[{"count":0,"href":"https:\/\/www.uri.edu\/news\/wp-json\/wp\/v2\/posts\/75504\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.uri.edu\/news\/wp-json\/wp\/v2\/media\/75505"}],"wp:attachment":[{"href":"https:\/\/www.uri.edu\/news\/wp-json\/wp\/v2\/media?parent=75504"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.uri.edu\/news\/wp-json\/wp\/v2\/categories?post=75504"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.uri.edu\/news\/wp-json\/wp\/v2\/tags?post=75504"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}