AsianScientist (Aug. 31, 2016) – A Japanese research group has demonstrated for the first time that an impact with a large meteorite was responsible for the mass extinction of marine organisms during the late Triassic period nearly 215 million years ago. The work was published in Scientific Reports.
In 2013, evidence of an impact dating back 215 million years involving a meteorite several kilometers in diameter was discovered in a claystone layer embedded in exposed chert rock along the Kisogawa River in the town of Sakahogi, Gifu Prefecture, in central Japan. However, the effects of the impact on Earth’s environment, including whether it had led to the extinction of marine life inhabiting the oceans at the time, was unknown.
The research group of Professor Yasuhiro Kato at the Frontier Research Center for Energy and Resources at the University of Tokyo, together with their collaborators, investigated the extinction patterns of marine organisms by studying the fossils of radiolarians (a type of protozoa) and conodonts (extinct eel-like creatures). These fossils were taken from the late-Triassic chert in Sakahogi.
The researchers discovered that a large number of radiolarians and conodonts became extinct in the period immediately following the impact. The team also discovered that the production of phytoplankton dropped significantly for tens of thousands of years after the impact, and the number of radiolarians also decreased during the same period.
Interestingly, they also found that new species of radiolarians that did not exist before the impact emerged after production of phytoplankton was restored, eventually replacing older species and driving them into extinction.
“Revealing how a mass extinction occurred in the past provides us with important clues for predicting the influence of future environmental changes on the Earth’s ecosystems,” said Kato.
The research group aims to expand its study to evaluate the effects of the impact on other life forms inhabiting the Earth at the time, including mammal-like reptiles, dinosaurs and other land organisms.
The article can be found at: Onoue et al. (2016) Bolide Impact Triggered the Late Triassic Extinction Event in Equatorial Panthalassa.
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Source: University of Tokyo.
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