Oxygen-powered Megafauna

Twice recently the supposition that increased oxygen levels in a purported antediluvian Earth might explain the enormous size of certain organisms, as well as myths of giant humans, has been advanced.On the face of it, this seems stupid to me. If it were possible to drastically increase one's size with oxygen, then wouldn't people do that? It's not hard to equip someone with an enhanced supply of oxygen; there's a considerable medical industry devoted to doing that for emphasemics, etc.So, what's the deal with this? Why does anybody ever offer this in any kind of seriousness? What's the research that shows that increased oxygen levels can magnify the size of otherwise unremarkable individuals, or that this phenomena extends across all species?Or, as I suspect is the case, is this just something we hear because creationists have absolutely no problem with inventing whatever ludicrous ad-hoc-ery they need to support their immediate point?Er, maybe it's better to reign in my question a little bit. Let's stick with "what's the research that shows that increased oxygen levels magnify the size of organisms?"(Edit: Fixed first sentence. That sentence no verb.)This message has been edited by crashfrog, 12-01-2004 09:49 PM

Thread moved here from the Proposed New Topics forum.

Off the top of my head-Wouldn't the oxygen claim suggest that height/size in humans/animals would vary inversely with elevation?

Yes, exactly. Are people much shorter in Denver than they are in Death Valley? (Bad examples maybe but it's the high-low extreme I could come up with.)

well evolution doesn't work on individuals, only populations, and wit ha lot of time. you should know that!i love it when creationist bawk at simplistic evolution, and then suggest something really off the wall that involves a much, much weirder evolutionary change to justify their support of a literal bible.

I don't know much about the topic. However, I have heard that a sudden drop in oxygen level might have contributed to the extinction of the dinosaurs. I saw on the discovery channel once that they found an amber with a pocket of air from dino times. They indeed found that the oxygen level in there was much higher than our atmosphere today.Any thought?

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Hate world.Revenge soon!

sounds like creationist propaganda.or at worst, coincidence. they did have more plants then...

How can it be creationist propaganda? The program admitted that the amber they got was around 50- 60 million years old or so. Besides, I really can't think of any reason why the hypothesis would support creationism.

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Hate world.Revenge soon!

eh, i just said "sounds like."i dunno; i didn't see the program. but you can't trust everything you see on tv.but like i said, the atmosphere MAY have had a high oxygen level. i've heard evidence that prior to the development of animals, plantlife had raised the o2 in the air so high that the a good section of the continent burned to the ground in a wildfire (lasting more than a year, i think). this brings up thoughts that maybe animals were just a way to keep plants alive, and avoid catastrophes like that. but then again, my prof may have just been joking...but with the growth of the human race on this planet, i wouldn't be terribly suprised if we ourselves lowered the o2 level on the planet by quite a significant amount.

Even if dinosaurs evolved to live in a highly oxygenated atmosphere, and died off following a catastrophic drop in oxygen levels (meteor impact, darkened skies, massive flora death, yadda, yadda...) - this would not mean that dinosaurs and other life simply grew bigger, or lived longer, because of high oxygen levels.A more general question to the group; do high atmospheric oxygen levels increase free oxygen species in an organism? If that is the case, higher oxygen levels would actually reduce lifespan...(By the way, Lam - did you see my recent 'Gay Gene' topic? It explains why you have so many nieces and nephews...)

I think there are several questions involved here.Was the oxygen level higher in the past?Was there a general trend where things were all bigger?Is there a correlation in timing between the two issues?While it does appear that there is some indication that oxygen levels might have been higher in the past, I would have to say that we just don't have a good answer there yet.On the second question, I have never seen anything that indicated that there was much difference in size distribution in the past when compared to today. There were big Dinosaurs, but there were many, many more small dinosaurs. The biggest dinosaurs were big, but not bigger than a Blue whale or Sperm whale.If the oxygen levels were higher we shouold also see smaller plants. Plants should grow larger in relation to carbon dyoxide and not oxygen. Yet there are examples of large ferns and other plants at the same time as the large Dinosaurs.Finally, on the last point, if oxygen levels were higher in the past and steadily decreased, and if there was a correlation between oxygen content and size, we should see a general trend over the whole history of critters going from very large to much smaller. Is there any indication in the record that would support such a hypothesis?

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Aslan is not a Tame Lion

A peer-reviewed paper on the subject: Page not found | Ecology and Evolutionary Biology

Here I was going to post my vague recollections on 35% oxygen in the Carboniferous, and you go posting one step from the primary literature! Thanks, Mr Jack! Note, though, that the o2 levels were back down to near-present ones before the first dinosaur hatched. The high levels were in the days of 50-centimeter dragonflies.

Google is my friend. Not only that but they were lower than current levels during the Triassic and early Jurassic periods - when some really pretty big dinosaurs were kicking around (although I think the biggest emerged in the Cretaceous, IIRC?).I think it's also important to note that the author discusses taxons of animals who absorb large amounts of their oxygen through their skin rather than having a mammal-like circulation. I suspect the effect of oxygen levels on the maximal sizes of such creatures will be much higher since they are more reliant on partial pressures to get oxygen into the deeper parts of their bodies. Thus they aren't, I suspect, transferable to creatures such as mammals and dinosaurs.

Thank you sir. Very interesting.Unfortunately, as is so often the case, that simply raised even more questions. It did not answer most of my questions though, for example is there any support for a belief that there is a general trend of decreasing average size of critters over time?

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Aslan is not a Tame Lion