Bivalve Census Reveals Echo of Ancient Mass Extinction

[Adsos Letter]

Source: University of Chicago

Newswise — Paleontologists can still hear the echo of the death knell that drove the dinosaurs and many other organisms to extinction following an asteroid collision at the end of the Cretaceous Period 65 million years ago.

“The evolutionary legacy of the end-Cretaceous extinction is very much with us. In fact, it can be seen in virtually every marine community, every lagoon, every continental shelf in the world,” said University of Chicago paleontologist David Jablonski. It is, he said, “sort of an echo of the big bang for evolutionary biology.”

This conclusion followed a detailed global analysis of marine bivalves, one of the few groups plentiful enough in the fossil record to allow such a study, which was funded by the National Aeronautics and Space Administration. Andrew Krug of the University of Chicago, Jablonski and James Valentine of the University of California, Berkeley, examined the geologic ages of every major lineage of living bivalves the world over, from oysters and scallops to quahogs and cockles. Their report appears in the Feb. 6 issue of the journal Science.

The team followed procedures similar to taking a census of everyone living in Chicago, inferring birth rates from that age profile, and then comparing them to a census for Tokyo, Mexico City and other major international metropolitan areas.

Their analysis quantified the time of origin for 711 lineages of bivalves living in the oceans today, and converted them to evolutionary origination rates. In all but the highest-latitude locations, the team saw the clear signs of a strong increase in origination rates following the end of the Cretaceous.

http://www.newswise.com/articles/view/548701/

[crimsonblue]

1. It doesn't seem like this article adds much new knowledge

I mean, I learned about this exact stuff last year in an intro-level bio class. After any extinction period, there is always an explosion in species and population size, due to a decrease in competition. I guess the only enlightening new fact is the proof that population growth never declines to pre-extinction levels. But, this too makes sense, as the explosion increases the total population size, meaning that life will be more resiliant to a slowing of growth.

[BlooInBloo]

3. The vast majority of scientific effort is spent confirming those generalities you happily cite...

with specific instances, crossing various i's and dotting various t's, and a brazillion other non-sexy things. Newton gave us 3 + gravitation. A whole host of non-sexy confirmations, applications, limitations, and clarifications came after for the next few hundred years.

[crimsonblue]

4. Yeah, I guess that's just a part of science--

the constant desire to prove easy-to-make assumptions. This is definitely a good thing, because commonly held ideas are constantly being refined, redeveloped, or rejected. I guess this is why science is believable. :D

[WheelWalker]

2. ich bin ein bivalve.