Link between comets/asteroids & extinctions

[Waspie_Dwarf]

Scientists find link between comet and asteroid showers & mass extinctions

Mass extinctions occurring over the past 260 million years were likely caused by comet and asteroid showers, scientists conclude in a new study published in Monthly Notices of the Royal Astronomical Society.

For more than 30 years, scientists have argued about a controversial hypothesis relating to periodic mass extinctions and impact craters - caused by comet and asteroid showers - on Earth.

In their MNRAS paper, Michael Rampino, a New York University geologist, and Ken Caldeira, a scientist in the Carnegie Institution's Department of Global Ecology, offer new support linking the age of these craters with recurring mass extinctions of life, including the demise of the dinosaurs. Specifically, they show a cyclical pattern over the studied period, with both impacts and extinction events taking place every 26 million years.

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[Lilly]

I'm not liking the time period between the last one of these events and now.

[bison]

Judging by the chart in the article, the last alleged burst of cratering was about 17 million years ago, and the last supposed wave of extinctions around 11.6 million years ago. Not a very convincing match. The next theorized burst of cratering is apparently still about 9 million years in the future, so not immediately threatening.

[Waspie_Dwarf]

the last alleged burst of cratering was about 17 million years ago, and the last supposed wave of extinctions around 11.6 million years ago. Not a very convincing match.

To dismiss a hypothesis based on the poor correlation of one occurrence whilst ignoring the excellent correlation at other times shows poor reasoning.

You are making the totally false assumption that for there to be evidence of cause and effect between a periodic increase in impacts and mass extinctions there must be evidence of a mass extinction EVERY time. This is simply not true, nor is it the claim that every peek in impacts correlates to a mass extinction. Nor is it the claim that EVERY mass extinction is caused by the periodic increase in impacts. The article says the following:

Specifically, he and Caldeira found that six mass extinctions of life during the studied period correlate with times of enhanced impact cratering on Earth.

The graph shows 10 mass extinction events. Removing your false assumptions we still have a very good correlation between these events 6 times, that seems highly unlikely to be a coincidence.

Edited October 29, 2015 by Waspie_Dwarf