In a news feature in the latest issue of Nature a team of geologists lead by Paul Olsen and Dennis Kent are in search for evidence that connect the end-Triassic mass extinction with the Rochechouart impact crater in France, which recently was dated to 201.2 ± 2.0 million years ago (Schmieder et al., 2010). Triassic-Jurassic boundary rocks in the UK are known to contain disturbed sediments close to the level of extinction, and Simms (2003) suggested that these “seismites” were in fact impact related.
The Rochechouart is a farly small impact crater, measuring only 20-25 km in diameter compared to the 180 km width of the Chixculub impact crater of the Cretaceous/Paleogene event.
Could the Rochechouart impact have helped cause the end-Triassic mass extinction event?
Well, Olsen makes sure all angles are covered:
“Perhaps it was one of a series of asteroids that hit around the same time. Alternatively, a lone French crash might have been the final straw for a world already reeling from volcanic eruptions. Or the impact may have come first, weakening ecosystems enough that when the eruptions started, life took a nosedive.”