Discussion in 'Biology & Genetics' started by EndLightEnd, Nov 8, 2008.
Trolls repeat them selves even if disproven before, don't feed them.
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The direct quotes speak for themselves. No butchery necessary.
No. Unless it were going the other way.
I dispute your scale there. 3 feet looks more like 6 feet. And what about Titanotheres and the like? Organisms have only been getting smaller on specific, narrow scales.
Exactly; thus demonstrating the self-evidence of my claim.
No it doesn't. Any trends are over specific periods - 10 million years or so - broken up by extinction or by achievement of the asymptote for size in a particular period.
This conversation is decades old, but since it is about what I was working on I will reply here. Maybe some of you all around to bounce some ideas off of. At any rate. The Oxygen levels that have measured have changed over the years I suppose, but I think I like the USGS direct measurements of air bubbles in the amber sample which show the levels could have been as high as 35% O2, vs the 21% of today's. So directly, a slight performance in muscle efficiency could have some support for limits in that there is a limit for how cross sections of muscles show that eventually they become rather too large to be able to move even themselves. Kind of. At any rate, the change from 30%, using a smaller figure, vs the 21% increases the weight of the entire atmosphere by 12.5% roughly. What follows then, using Bernoulli's equation of fluid dynamics and comparing some apples and apples, I've estimated the barometric pressure to be double that of 1 atmosphere, simply by comparing the wight of Oxygen vs Nitrogen etc.... Furthermore. It is reasonable also to infer that some atmosphere would have been lost to the Chicxulub event through ejection. We don't usually see much in the way of calculations for what atmosphere would be ejected because we are usually more interested in the debris and dust etc. I can't really even find very much in the way off water ejected, let alone atmosphere. SO, given that I have no number I would put a small number in the atmospheric pressure change from ejecta, but even a small percentage makes a large difference using Bernoulli. If the atmosphere lost 1% in overall mass, the effect is equal to the difference from Everest to sea level. Still a number worth considering. So 1% would be another 60% increase in atmospheres going to the time before the impact. I will shrink that to 50% for obvious reasons or maybe even 30%.. So 230% increase in atmospheric pressure from Oxygen loss to Nitrogen and half a percent lost to the impact. The question then IS: what impact would this actually have on size of insects and ridiculously large dinos? Would this help explain their seemingly unreasonable size? Do you think?
MRI & DNA mapping etc is not.
i like brians comments about cell function & vascular system & body temperature etc...
question: blood science
can blood as currently understood carry the extra oxygen to make the muscles perform at a higher rate ?
is there any density ratio ?
has there been any recovery of dinosair muslces ?
is there any evidence of mineral desposit change in dietary availibility that would allow for stronger bones & muscle fibers etc ?
I have no answers for any of these, but also think the actual increase in O2 has an effect on the size potential of organisms, but it does not seem enough to account for everything; the largest extreme examples being a dozen or more the size of fully grown elephants. I think that more red blood cells might be produced to provide the carriers to provide more O2 to the working parts, but that's just based on surface reading. The main question I have for anyone with some biology background to maybe ascertain if higher barometric pressure, will in fact also support larger organisms. I think the combination might be true. It is not as though a pressure of two, or three atmospheres, would add much in the way of a buoyancy effect, but perhaps it would help sustain, or increase the potential size, of large insects, or dinos.
As well; I find it interesting that higher O2, does increase the atmospheric pressure as well as increasing efficiency. Between these two facts, there might be enough difference in modern environment to help explain why it is possible to have a two meter dragonfly, and a dino the size of four firetrucks. just a notion really, but interesting to myself and some friends.
from what i have heard say from biologists that answer is no.
the cell wall is not strong enough to support the pressure.
there has been some considerable discussion over the years about the height issue around pumping blood to very high heads and thus brain size limitation due to the ability to provide enough blood.
Carbon based life forms are only possible to achieve a certain size to strength ratio.
that ratio is shared by the insect world which makes insects very strong.
however, what is constant is 2 things
1 first and formost gravity
2 the properties of water(carbon based life forms with vascular systems that are predominently water based life forms).
you need to do a bit of speed reading on this subject
higher O2 does not counter gravity of carbon based life forms basic design.
The larger the creature the bigger the amount of food it must consume to function.
good luck with your study
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IMO, an abundance of food is the main reason for size. However, space has also been proven to affect size over time.
On small islands the same species tend to be smaller than say on large plains.
Humans appear to break the mold, due to their ability to grow food rather than relying on available food. However there are still some common denominators.
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The things you have laid out here are things that would be not different from the current environment. The cell wall not being able to support higher pressure does not make very much sense to me considering that a diver can withstand many many atmospheres, or that fish and deep sea creatures are abundant. Cell structures are certainly capable of supporting higher pressures evidently.
Yes big dinos would have to eat more, just like cows eat more than me.
Higher O2, means higher barometric pressure. O2 weighs more than Nitrogen. The math suggests about twice the barometric pressure. And that is to trade Nitrogen and Oxygen equally in the ancient atmosphere. If we were to simply add the volume of O2 to the whole, that would end up making the pressure about 5x current measures. I am using the smaller option. To what degree the effective 'buoyancy' would be from the added pressure and weight, would certainly help blood pump higher, as well the weight of the creature related to its biomass could certainly decrease the effects of gravity. Higher pressures would take less energy to get the O2 and blood up long necks. IF, there is much of an effect on this 'buoyancy' that I am picturing. It is not exactly the same effect of buoyancy in water, but not just due too the extreme pressures related to the weight of water. Water (liquids) are not compressible like gases are. There is not much reading to do really because it's not very testable without growing organisms under differing environmental pressures. A fruit fly experiment would do wonders. I wonder if anyone ever ???
Whoa, FOUND IT... Yes extra O2, and also the related Barometric pressure increase to emulate the 30% O2, grows bigger fruit flies in as little as three generations. Well what do you know. Chapter 25.6 in this text book:
So for sure for insects I would say is nailed. Dinos???? Well, all we need are a couple of dozen breeding pairs of elephants and we can grow half of them under two or three atmospheres. we'll go ten generations, and see.
https://books.google.com/books?id=W... under different barometric pressures&f=false
In spite of or maybe due to their size, their efficiency ratio is better than most smaller animals.
Cell walls do not experience any stress so long as the pressure on both sides is equal, as it would be in any organism. From the chemistry perspective, the important thing is the partial pressure of oxygen. If there is 30% O2 in the atmosphere, instead of 20%, then even if the total atmospheric pressure is unchanged, reactions and diffusion processes will go at 150% of the rate - and support larger organisms.
Note, by the say, when using insects as an example, the correlation between their size and the density of the atmo has far more to do with the lifting power they can get.
Flight has an extremely expensive cost to any animal's energy budget. So denser air gives them an advantage.
It would be a mistake to extrapolate from flying animals to terrestrial animals.
That's not at all what biologists are saying. It's an idea perhaps, but this is not one of the things being mentioned much anywhere (your flying ideas) , even though I was able to find only the one mention of barometric pressure, for the fruit fly example. Biologists are saying it is far more likely that it is the limits of the way they (insects) get their oxygen internally distributed, the mass (or weight) of their exoskeletons limiting their size etc. If the size and wight constraint, as well as the overall efficiency of the organism due to the saturation of O2 & the added pressure experiment, then why would these common issues between organisms have no effect. Efficiency, and added O2 boost would help the insects grow larger in the ways mentioned, why not the dinos. I think you are in error to claim there is no correlation. There is no proof of this notion I have toyed with over the past week or so, but the evidence and experiments and math seem to point that pressure and o2 could have one of the effects necessary to support gigantosurusussssss, and also may help explain why they fell to the ground in masses, (along with the apparent loss of food of course, which also seems quite obvious.)
It would be equally blunderous to assume there is nothing to it, given that the fruit flies nearly doubled in size under roughly double the atmospheres. Something you could look into is what effect or aid this would have biologically if it were then easier to fly due to. If it were easier to fly, why would there be reason or advantage to largeness. I don't follow you. Easier to fly would be an advantage. Easier to grow bigger because of this advantage? Maybe add something to the earlier speculative growth rates due to pressure increase. Why not? Sure. I suppose.
Biology link below discussing modern limitations, some perhaps environmental, some adaptive genetics.
We are certainly looking for common environmental diferences that would help explain gigantic versions of similar species, like insects of today or bird sizes compared to todays birds, or maybe elephants or rhinos. Just because they are the limit of warm blooded creatures today perhaps. Anyhow, since the fruit flys imediately responded by growing bigger, would that also be common code, you know; to be bigger. It might be a common thread that generally bigger is better overall due to the intrisic advantages. plant eating dinosaurs and giraffes certainly have reason to be larger. Fish get huge in ponds if not harvested, the insects were bigger apparently because they could? Natural selection will certainly curb size from being harvested, but if unchecked perhaps it is a common biological advantage. Quicker to get around to find food... Certainly we are looking for things that were different but also would have the common effect of increasing size. I think O2 and pressure have the biggest advantage to give but that's just me. The math is there, some experimentation agrees so it's worth considering IMO.
Yes, that's an upper limit. It prevents them from growing larger than a certain size; it doesn't explain why they would grow larger in the first place. IOW, you're countering apples with oranges.
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