Hullabaloo

Thursday, May 07, 2009

 
Dung Beetles And Other Things

by tristero

Very cool. Seriously, don't miss this podcast even if you're not a science geek; it will blow your mind. Doug Emlen, an expert on dung beetles, gives a wonderful introduction to their amazing world. And he has some distressing news to impart about pre-ground canned coffee...

(Also, the segment on Westbound Records is worth a listen. Terrific music.)

And while we're on the subject of science, it looks like more evidence is accumulating that H. floresiensis, aka the hobbit, really was a separate species.. The Times had a more detailed report yesterday. That's one long foot for such a small creature!

Finally, unfortunately, it's been a pretty bad few weeks for Mexican self-esteem. In addition to swine flu, turns out that the famous Chicxulub impact crater may not be directly implicated in dinosaur extinction at the KT boundary 65 million years ago. Bummer:

[As quoted in Greg's blog]The newest research ... uses evidence from Mexico to suggest that the Chicxulub impact predates the K-T boundary by as many as 300,000 years. "From El Penon and other localities in Mexico we know that between 4 and 9 metres of sediments were deposited at about 2-3 centimetres per thousand years after the impact. The mass extinction level can be seen in the sediments above this interval" says Keller.

Advocates of the Chicxulub impact theory suggest that the impact crater and the mass extinction event only appear far apart in the sedimentary record because of earthquake or tsunami disturbance that resulted from the impact of the asteroid.
'The problem with the tsunami interpretation' says Dr Keller, 'is that this sandstone complex was not deposited over hours or days by a tsunami; deposition occurred over a very long time period'.

The study found that the sediments separating the two events were characteristic of normal sedimentation, with burrows formed by creatures colonising the ocean floor, erosion and transportation of sediments, and no evidence of structural disturbance.

As well as this, they found evidence that the Chicxulub impact had nothing like the dramatic impact on species diversity that has been suggested. At one site at El Peon, the researchers found 52 species present in sediments below the impact spherule layer, and counted all 52 still present in layers above the spherules. In contrast, at a site at La Sierrita which records the K-T boundary, 31 out of 44 species disappeared from the fossil record.

"We found that not a single species went extinct as a result of the Chicxulub impact...these are astonishing results that have been confirmed by more studies in Texas" says Keller.

Greg explains that it may not be as clearcut as Keller says. Then again, it may. Or even more likely, a little bit of both. Or not.

That's what I like about science: unambiguous answers.

[Special note for the sarcasm-impaired: Of course, I know that's not what science is about.]

[Edited and revised after initial posting.]

tristero 5/07/2009 06:20:00 AM |