Mass Extinction 215 Million Years Ago Was NOT Due to Asteroid or Climate Change

Asteroid Hitting Earth

According to a new study, the mass extinction that occurred 215 million years ago was not caused by an asteroid hitting Earth or by climate change.

A team of University of Rhode Island 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.

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.

URI graduate student Reilly Hayes (left) and undergraduate Amanda Bednarick examine an outcrop for fossils at Petrified Forest National Park as part of their research. Credit: Photo courtesy of Amanda Bednarick)

According to David Fastovsky, the URI professor of geosciences whose graduate student, Reilly Hayes, led the study, the global extinction of ancient Late Triassic vertebrates – the disappearance of which scientists call the Adamanian/Revueltian turnover – 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.

“Previous hypotheses seemed very nebulous, because nobody had ever approached this problem – or any ancient mass extinction problem – in the quantitative way that we did,” Fastovsky said. “In 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 – abrupt and synchronous.  In fact, it was diachronous and drawn-out.”

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 URI geosciences majors Amanda Bednarick and Catherine Tiley.

Hayes and URI Statistics Professor Gavino Puggioni then applied several Bayesian statistical algorithms to create “a probabilistic estimate” 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.

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 URI 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 and Paratypothorax, for instance, went extinct about 6 million years before the impact and 10 million years before the climate change, while those of Acaenasuchus, Trilophosaurus and Calyptosuchus went extinct 2 to 3 million years before the impact. Desmatosuchus and Smilosuchus 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.

“It was a long-lasting suite of extinctions that didn’t really occur at the same time as the impact or the climate change or anything else,” Fastovsky said. “No known instantaneous event occurred at the same time as the extinctions and thus might have caused them.”

The URI 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’t available at other sites and for other time periods.

“This 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,” he said. “Other extinctions could potentially be studied in a similar way, but logistically it’s a tall mountain to climb. It’s possible there could be other ways to get at it, but it’s very time consuming and difficult.”

Reference: “Modeling the dynamics of a Late Triassic vertebrate extinction: The Adamanian/Revueltian faunal turnover, Petrified Forest National Park, Arizona, USA” by Reilly F. Hayes, Gavino Puggioni, William G. Parker, Catherine S. Tiley, Amanda L. Bednarick and David E. Fastovsky, 3 January 2020, Geology.
DOI: 10.1130/G47037.1


View Comments

  • How will plants that rely on Honey Bees germinate once bees go extinct?
    Will there be a mass shortage of essential grains like wheat. flour and rice? How will agricultural scientists react to prevent mass hunger? Thank you.

  • What do bees have to do with this article? Who even said that bees are going extinct? This is nonsense to say the least.

  • Just so readers are aware, this extinction event happened WITHIN the Late Triassic Period, 215 million years ago (when some of the more famous early dinosaurs like Plateosaurus were just starting to emerge onto the world stage). The article mentions this once, but it’s easy to gloss over. It is NOT the more famous End Cretaceous extinction of 66 million years ago (which wiped out most non-avian ancestral dinosaurs), nor is it the earlier End Permian extinction (aka “The Great Dying”) of 252 million years ago, nor is it even the slightly later End Triassic extinction of 201 million years ago. Again, this is in reference to a very little known extinction event WITHIN the Late Triassic itself. I don’t believe the article made that point very clear to the casual reader, so I think it’s worth mentioning again.

  • Well you should pay more attention because yes Bees 🐝 are struggling to survive due to certain pesticides in our environment

  • The time period of the study is 18 million years. Bees, timeframe, what - twenty ? Are they really comparable ?

  • This is ridiculous! Theyre basing all this baloney from one site in one continent. So? Because there was definitely mass extinction because of one or more meteors diesnt mean all dinasours were wiped out. It's quite possible millions survived in pocket regions. Then later died out from some othe catastrophe. These researchers are totally off base and clueless.

    • Publish a rational refutation including peer reviewed literature citations and possibly, just possibly your incredulity will have merit. Other than that your comment is a sad testimony to what I am almost certain is your proud and earned scientific illiteracy.

  • I don't have educational letters behind my name signifying a specific discipline of education (arguably indoctrination) but I have wrestled with the evidence for 30 years including 24 years of observational travel in the Rocky Mountain intermountain states, the middle east and northern and eastern Africa. My imagination can never truly discount the effect of a worldwide flood with rampant and aggressive volcanic activity (protecting the atmosphere). Simple observational approach over hundreds of miles and in different parts of the world cannot fully discount such things imo I have no agenda just...I don't understand why such things are considered toxic aside from philosophical/religious reasons. 'Science' in many ways has experienced a coup de etat of statistical math with a blind reliance on predecessorial faith. Ridiculous. My rambling 2 cents worth

  • Cauldron's comment is excellent -. This is not the extinction event everyone thinks of as the end of the dinosaurs- that is an entirely other event but this article seems to written to sensationalize an academic report by associating it with that other well known event.

  • Wow such word salads from some of you guys. How am I to even compete with wordings as simple as a guy like me? I feel like a man not wearing a silly hat at a silly hat party.

    But the bees. I agree with the woman about the bees. We are here seeing it happening. Can't say the same for us and Dino's.

    I like avocados in my salads.

  • I instictively distrust results which come from "several Bayesian statistical algorithms" which are designed "to create a probabilistic estimate” of anything. It seems to me that what "Bayesian statistical algorithms" usually create is whatever preconceived ideas were in the heads of the people who created the algorithms.

Todd McLeish, University of Rhode Island

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