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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.

Meteorite
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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Ignorance perpetuates
By Shadowmaster625 on 10/30/2012 2:50:12 PM , Rating: -1
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.




RE: Ignorance perpetuates
By Mitch101 on 10/30/2012 3:02:09 PM , Rating: 2
Heck with Mammals what about Megalodon? Its not like people over fished the oceans back in the day and Im not sure Orca's could have wiped them all out.

With great white its you that is afraid to be in the water with Megalodon your afraid to be in a boat in the water.


RE: Ignorance perpetuates
By Enoch2001 on 10/30/2012 3:15:24 PM , Rating: 4
quote:
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
quote:
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.


RE: Ignorance perpetuates
By conquistadorst on 10/30/2012 3:21:41 PM , Rating: 4
Yes folks, and that's why there aren't any species of animals that lay eggs on the ground today. It's because of those mammal egg-stealing whippersnappers. That's also why there aren't any mammals that can climb trees, it's too hard for mammals to do that and evolution is unable to find a way to help them. It's a proven fact that eggs in high places cannot be reached.

I assure you, absolutely no dinosaurs were harmed by the meteor that hit our Earth 65 million years ago and created a 180km crater. Absolutely none! You know, the 1000m high tsunamis, blotting out the sun from the sky disrupting photosynthesis for months, globally igniting wild fires, earthquakes, and volcanoes. That's all child's play, no effect on dino mortality!


RE: Ignorance perpetuates
By retrospooty on 10/30/2012 3:47:46 PM , Rating: 1
I don't think you are understanding the point. Populations were already on the decline, severely when it hit... Therefore the effect was extinction. Had there been higher #'s with the conditions that existed millions of years prior, it probably would not have led to extinction.


RE: Ignorance perpetuates
By conquistadorst on 10/30/2012 4:10:40 PM , Rating: 2
No, I followed his point and I was poking fun at it. He bluntly said:

quote:
Dinosaurs didnt die because of a meteor.


You also cannot simply take a line graph and extrapolate it over time and say "yes, definitely extinction due to egg stealing. No other plausible explanation. Everyone else is ignorant tee hee!". That's not even science. And yes, it's certainly plausible it was the culmination of many events together that led to their extinction. But that was certainly not what he said.


RE: Ignorance perpetuates
By retrospooty on 10/30/2012 5:37:27 PM , Rating: 2
ok... I was more referring to the fact that population was already declining, that they can tell. How and why could be debatable/


RE: Ignorance perpetuates
By docinct on 10/30/2012 5:36:03 PM , Rating: 2
"That's also why there aren't any mammals that can climb trees"
I assume that is a joke otherwise the lemurs, squirrels, rats, possums, mice, gibbons, etc. of the world will be insulted.


RE: Ignorance perpetuates
By Azethoth on 10/30/2012 7:39:12 PM , Rating: 2
No it is not a joke. It is sarcasm. May as well be sarcastic since the OP is either trolling or a special brand of ignorant.


RE: Ignorance perpetuates
By conquistadorst on 10/30/2012 8:10:36 PM , Rating: 2
quote:
I assume that is a joke otherwise the lemurs, squirrels, rats, possums, mice, gibbons, etc. of the world will be insulted.

Yes it was most certainly trying to drown it in sarcasm. I was mocking the OP and pointing out just how preposterous his theory sounds where walking dinosaur's went extinct just because mammals were so good at stealing their eggs. Perhaps I didn't make my reply as painfully obvious as I had thought.


RE: Ignorance perpetuates
By aurareturn on 10/30/2012 4:41:15 PM , Rating: 2
quote:
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.

So you're telling me that the most dominant specie on earth died off because they couldn't protect their eggs?

Wouldn't the dinosaurs just evolve egg protecting behaviors to counter the mammals?

I just find it hard to believe that the mammals were able to own the dinosaurs until none of them survived.


RE: Ignorance perpetuates
By dgingerich on 10/30/2012 5:31:24 PM , Rating: 3
quote:
(All oceans are less than 200 million years old.)


This is enough for me to call BS. This points directly to the origin of life and our source for oil.

Way back in the period of 350M to 400M years ago, we had one huge continent and one hug ocean, with more ocean coverage than we have today. This also allowed for very large calm areas in the ocean where huge algae blooms formed. As that algae died, it sunk into the ocean, creating an oxygen free dead zone underneath it, where the dead algae gathered and was eventually covered with sediment, thus the reason most oil is discovered combined with sand. After it gets covered, the algae slowly degraded under pressure and heat to become the oil we know today.

Going further back, life on earth couldn't have formed on land because the ozone layer hadn't formed yet, making the surface completely uninhabitable because of ultraviolet light. The first complex life forms that we see in the fossil record formed stromatolites in the ocean, converting CO2 and water into O2 and sugar, and helping to change the atmosphere to an Oxygen rich one, eventually forming the ozone layer, making way for life on land tens of millions of year later.

So, the statement that oceans weren't around until 200 million years ago is totally bogus.


RE: Ignorance perpetuates
By Uncle on 10/30/2012 6:29:24 PM , Rating: 2
May I add,I think this is the third trip around the world for the Continents.


RE: Ignorance perpetuates
By Azethoth on 10/30/2012 7:42:06 PM , Rating: 3
Yes, Pangea, Gondwanaland and Whatsisland (the one that time and I forgot).


RE: Ignorance perpetuates
By Brutus1234 on 10/30/2012 8:16:44 PM , Rating: 5
I thought they went extinct 6000 yrs ago because Jesus rode them too hard in his Holy Dinosaur Rodeo.

Your carbon dating is all just lies from the devil in hell


RE: Ignorance perpetuates
By drycrust3 on 10/31/12, Rating: 0
"Vista runs on Atom ... It's just no one uses it". -- Intel CEO Paul Otellini














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