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Re: SPECULATION: pterosaur extinction versus bird survival

There's an interesting graph at:


I find it fascinating, and I quote from some of the associated text:

"The following graph shows impact craters on Earth by age and diameter.
Also shown are the main geologic boundaries
involving mass extinctions (tall, bold lines), minor boundaries (thin,
short lines - fewer extinctions) and the approximate timing
of "flood basalt eruptions". Originally the graph only showed craters
which aligned with major extinction events but it was
considered better to show all craters 20km diameter or more to avoid
"counting the hits and ignoring the misses". Those which
appear to align with a geologic boundary are shown as dark blue

Jeff Hecht wrote: