Print 26 comment(s) - last by gamerk2.. on Nov 1 at 1:14 PM

Research shows that pre-extinction disruption of food webs makes ecosystems more fragile, susceptible

Jonathan Mitchell, a Ph.D. student on the University of Chicago's Committee on Evolutionary Biology, Peter Roopnarine of the California Academy of Sciences, and Kenneth Angielczyk of the Field Museum have collaborated to produce a fascinating simulations-based analysis of the factors that helped dinosaurs go extinct en masse at the close of the Cretaceous era.

The authors used a food web program they wrote, which looked at dozens of species.  They looked to lay to rest debates about dinosaurs' diet (e.g. did T. rex eat Triceratops, Duck-Billed dinosaurs, or a mixture of both?) by carrying out a number of simulations with each possibility considered.  A total of 17 food webs, based on species alive at the time, were inspected

What they found was that the precise diet of dinosaurs mattered less than the relative diversity of one ecosystem versus another.  Comments Professor Angielczyk, "Using modern food webs as guides, what we have discovered is that this uncertainty is far less important to understanding ecosystem functioning than is our general knowledge of the diets and the number of different species that would have had a particular diet."

The researchers suggest that climate change in the Cretaceous led to a number of changes, including the drying of a sea in North America.  The net result was a loss of diversity.

Creataceous food web
Lower food web diversity made the dinosaurs more vulnerable to mass-extinction a new study claims. [Image Source: PNAS]

This meant that while the ecosystem was still flourishing, it was respectively more fragile than its equivalent, 13 million years before the meteorite impact at Chicxulub on the Yucatan Peninsula.  Comments Mr. Mitchell, "The ecosystems collapsed because of the asteroid impact, and nothing in our study suggests that they would not have otherwise continued on successfully.  Unusual circumstances, such as the after-effects of the asteroid impact, were needed for the vulnerability of the communities to become important."

In fact, the authors argue that the dinosaurs would likely have survived the calamity, had the meteorite hit 13 million years earlier, during the period of greater diversity.

If the meteorite hit 13 million years earlier, the dinosaurs might not have gone extinct.
[Image Source: D. Davis]

The authors say their analysis provides cautionary hints to help assess current ecosystems for vulnerability.  States Professor Rooparine, "Besides shedding light on this ancient extinction, our findings imply that seemingly innocuous changes to ecosystems caused by humans might reduce the ecosystems' abilities to withstand unexpected disturbances."

However, the authors are also careful to note that their study did not indicate more species was a significant safeguard; rather they argue it's the amount of genetic diversity across species that's important -- in other words, saving a lot of similar species may not help as much as conserving species that play unique roles in the ecosystem.

The study was published in the prestigious peer-reviewed journal Proceedings of the National Academy of Sciences (PNAS).

Sources: Eurekalert, PNAS

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RE: Ignorance perpetuates
By Enoch2001 on 10/30/2012 3:15:24 PM , Rating: 4
Dinosaurs didnt die because of a meteor. The fossil record was declining linearly before "the event" 65 million years ago. Dinosaurs went extinct because their migratory paths were cut by the expanding oceans at that time. (All oceans are less than 200 million years old.) Mammals continually raided the dinosaur nests to the point where they could no longer keep up their numbers. Mammals just became too adept at making a living off dinosaur eggs, their numbers grew too great, and there simply was no way for dinosaurs to counter them. Except for the dinosaurs that could lay their eggs in high places unreachable by the mammals.... these became the birds.

An alternate theory to the meteor impact theory. Shall we consider yours as perpetuating ignorance as well?

RE: Ignorance perpetuates
By retrospooty on 10/30/2012 3:45:31 PM , Rating: 2
ACtually it was a combo of both "The fossil record was declining linearly before "the event" 65 million years ago" these are just what researchers have found by studying fossils nad sediment layers... Facts, not ignorance.

RE: Ignorance perpetuates
By Mitch101 on 10/30/2012 3:57:17 PM , Rating: 3
Maybe they all just tasted like Bacon.

RE: Ignorance perpetuates
By Bad-Karma on 10/30/2012 4:37:05 PM , Rating: 2
studying fossils nad sediment layers

I would not want that job.......

RE: Ignorance perpetuates
By retrospooty on 10/30/2012 5:38:46 PM , Rating: 2
damn this keyboard and damn those nads!

RE: Ignorance perpetuates
By Bad-Karma on 10/31/2012 1:17:21 AM , Rating: 2
I'm more concerned that there were enough of them to actually form their own sedimentary layers ! That's a whole lot of nads.....

RE: Ignorance perpetuates
By Ammohunt on 10/31/2012 11:41:54 PM , Rating: 2
RE: Ignorance perpetuates
By gamerk2 on 11/1/2012 1:14:53 PM , Rating: 2
Only for certain Species though; several families were thriving before the event. Your theory also fails to explain how ALL the families vanished at more or less the same exact time frame, or why OTHER species, particularlly 70% of all salt water species, went under during the same period.

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