Wednesday, April 20, 2016

[Geology2] Re: Dinosaurs 'already in decline' before asteroid apocalypse

Thanks, Lin. Speculation on dinosaurs is a perennial sort of entertainment, and great fun, I think.  They are such dramatic creatures in our imagination that it is difficult to see them objectively, and their violent destruction by nothing less than a giant fireball from heaven seems to verify their status as legend. It's the closest that science has come to describing something equivalent to an ancient Greek tragedy.  It's no wonder dinosaurs have remained popular for so long and keep inviting us to further speculation about the animals and their fate. 

I'm not an expert in this but the idea that they were finally killed off as a result of the meteorite impact seems reasonable and we have the likely culprit, staring out at us in the Yucatan.   It looks like some of the experts have settled on the theory that it was a one-two punch, with the volcanic activity setting the dinos up for the knockout by the meteorite, which is also reasonable, and that may be all that we can say at this point.  Destruction of the dinosaurs by the meteorite is easy to understand, but the declining number of species is more complicated.  If there are fewer species but a greater number of individuals can we say they are heading toward extinction?  I would guess that a changing environment, say lower temperatures worldwide, and changes in rainfall patterns would severely restrict many habitat areas for each species and result in extinction of a number of those species, thus lowering the generic diversity, but would not kill all  of them. The surviving species might expand because of lower competition and it might not be in any danger of extinction.

I could probably find the answers if I dug deeply enough in biology and paleontology books, but hey, that would take the fun out of it.




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