There is an interesting set of problems concerning dinosaurs.

There are three basic problems:

1) The first concerns the estimated mass of Sauropods and the limit of the strength of biological materials to support the dinosaur’s mass.

2) The second concerns the size and mass of pterosaurs (flying or gliding dinosaurs) and the biological limits of wing strength and fundamental aeronautical limitations to support the mass of a pterosaur in flight, based on the maximum estimated flight speed of a pterosaur.

3) The third concerns the limits of insect size based on the efficiency of insect’s breathing mechanism (insects breathe through their skin, so the amount of oxygen that they can absorb is proportional to their surface area) the amount of oxygen at standard temperature and pressure in the atmosphere.

These writers provide scientific analysis to support the assertion that there is a set of logical problems concerning dinosaurs and then present a possible hypothesis to resolve the paradox.

The hypothesis which the writers propose to resolve this paradox is that the earth’s atmospheric pressure was much greater at the time of dinosaurs. But first before discussing the proposed solution to the paradox is there a paradox?

I would be interested in papers that do or do not support the writers' assertion that is a dinosaur paradox.

Logical Inconsistencies Concerning Dinosaurs?
http://mb-soft.com/public/dinosaur.html#legs

Paradox of Large Dinosaurs?
http://dinosaurtheory.com/big_dinosaur.html

Mysteries of the Dinosaur Epoch Cases Solved?
http://www.emse.fr/~yukna/dinosaurs/..._dinosaurs.php

Was the Atmospheric Pressure different During the Time of the Dinosaurs?
http://www.levenspiel.com/octave/dinosaurs.htm

I only read the third link.

Nice misdirection. If I wasn't already well versed in the subject I would have been fooled.

Don't have time for a nice disection though, going to breakfast.


I'll be back.

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I don't get the connection between insects and dinosaurs. Also, insects do not quite breathe through their skin. They mostly use a network of tiny hollow tubes called trachea.

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There was a thread on some of this last month. Lots of good posters. Have a look.

Hi Disinfo Agent,

The following is an excerpt from the Wikipedia article that you linked to.

Fair enough, but the language you used was inaccurate. They do not 'breathe through their skin'. While it's probably true that 'the amount of oxygen that they can absorb is proportional to their surface area', this must take into account the many ramifications of the trachea inside their bodies, not just their body's outer size...

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Thanks PraedSt. There are some interesting comments in that thread. This thread adds the question of how to support a mass of a sauropod.

There are two similar issues, that mass of flying insects and reptiles vs the mass of current flying insects and reptiles and aeronautical limitations. The second is the limits of biological materials to support the mass of a sauropod?

This comment by Robison in that thread is interesting. I support Robison's comment that the book "The History of Oxygen" is interesting.

Oh No!: Pterosaurs couldn't soar, says expert


http://www.nick-lane.net/Extract%20chapter%205.html

Disinfo Agent, your comment is correct. My original comment was inaccurate.

Perhaps the question is how to explain gigantism at that particular period of time. I would expect that there was period when all gigantic animals and plants become extinct and then gigantism returned.

I read Lane's book "Oxygen the Molecule that made the World". Lane suggested that increased O2 expanded the giantic insects, but there is a problem with oxygen toxicity. Animals die in high levels of oxygen.

The hypothesis that the explanation to this paradox is an increase percentage of oxygen in the atmosphere has some problems, related to oxygen toxicity. The Gaia hypothesis has the biosphere regulating the percentage of oxygen in the atmosphere.


http://www.nick-lane.net/Extract%20chapter%205.html

Just one more nitpick (sorry): pterosaurs are not classified as dinosaurs.

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I had missed the problem of footprints when I read through the article. These guys are really thinking.

So there is a problem both with the biological limitations to support the massive dinosaur and then there is a separate problem that the dinosaur footprints should be deeper than observed in fossilized remains.

http://mb-soft.com/public/dinosaur.html#legs

Footprints

Speaking of footprints, this is fascinating:

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Ok, footprints have gone and made me interested. William, if you can Google up some articles with metric units, I would appreciate it. Thanks.

I think the discussion of footprints is missing a couple of important considerations:
1) Deep footprints in soft ground rebound: there's a hydrostatic effect which makes the base of the footprint rise when the weight is withdrawn.
2) Fossilized stuff gets squashed. As a thick moist layer turns into thin dry layer, the relief of any footprint is going to be reduced.

What we're reading is a poorly considered polemic, rather than science.

Grant Hutchison

Good debunking of some sauropod ATM here.

I was going to say the same and also add that when a path is walked often it sets hard in the sun and if there was a small shallow wet bit of mud it wouldn't penetrate deep enough to give a true reading of weight.

As for mating, they haven't even put into consideration about the size of males penis, as there isn't any evidence in a fossil of this soft tissue (if you pardon the expression). It is funny how our largest land mammal the elephant can manage this task and the females back legs cope!

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Now the rest of us politely skipped over that bit, Chrissy.

PraedSt, you might consider hunting down a copy of R McNeill Alexander's little book, Dynamics of Dinosaurs. It's rather old now, but it's a good primer for basic science and scaling laws.

Grant Hutchison

I didn't, it caught my attention.

But that article was trying to state that dinosaurs bones were lighter, like birds bones are now, otherwise mating would be impossible.

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Grant,
Have you read Wilson's "Evolution for Everyone"?
http://www.google.ca/url?sa=t&source...Tv6HISQXdC7P6Q

Shouldn't there have been an evolution advantage to limit the size of the animal?

Your comment concerning the fossil footprint record makes sense to me. (i.e. That there should be some sort of rebound in the ground, so the depth of the footprint fossil may not necessarily prove anything.) But I am thinking about the difficultly an 80 ton animal would have to walk through different terrain.

The writers are not anti-creationists. They are not saying sauropods did not exist. They are saying something was fundamentally different in the environment when gigantic animals and plants thrived which which partially removed a limit to gigantism.

Look at each claim individually.

The question of blood pressure and the length of the sauropod neck is interesting. Pressure is mgh. The writer is asking the question what is the evolutionary advantage of having a long neck if sauropod will die if it lifts its neck?

The question how could a pterosaur been physically capable of flying is a believe a currently unanswered question. I believe wind tunnel models and a basic analysis have not resulted in explaining how such a massive large animal could have flown.

I would disagree it follows logically that as science had some difficultly explaining how a bee could fly, that it follows that a pterosaur with a wing span the same as jet could fly, all else being the same as today.

I had heard a theory that only the young pterosaurs had the capability of flying however that does not makes sense as there would be no evolutionary advantage for the pterosaur's physiology.

Christine,
You comment that there is no reason why a Sauropod's could not mate makes sense to me. It should not have been included in the writer's list of arguments. Perhaps sauropods were anatomically re-arrange to allow a different position. As soft tissue is not preserved in the fossil record, there is no data to answer a mating question.

The issue of blood pressure and the sauropod's ability to support its mass is a different question.

I haven't.

There are benefits from large size, and benefits from small size. Evolution can shove in either direction.

That's right. And they're casting around and cherry-picking for all their worth to try to make a convincing case. When I see people shirking the obvious detail, I stop reading.

Grant Hutchison

WHy doesn't a Giraffe die?

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Oh, Pastor Johnson deals with that in William's first link:See, the giraffe manages fine, but there are no taller animals around at present, so it's clearly physiologically impossible for taller animals to cope cardiovascularly. Therefore, the taller animals in the fossil record obviously couldn't cope cardiovascularly. That's the argument, stripped of exclamation marks and capital letters, unfounded claims about cardiac muscles, and a little confusion about how heart valves work.

Grant Hutchison

Giraffe cause a local increase in air pressure by creating particles with their horns through interactions with cosmic rays.

No wait, it's because they have valves in their neck that stops them dying when they lower their heads.

I will point out that we have insects with half meter wing spans today in Queensland. They have beautiful purple wings, although you might not appreciate them if one happens to splat against your windshield while you're driving.

Who might those insects be?

Another point I was going to make CS.

My Bold.

But it was included so I pointed it out. I don't think a different position would be the case for mating to happen.

As for blood pressure HERE is an example of a giraffes way of coping.

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You can please some of the people all of the time and all of the people some of the time. But you can not please all of the people all of the time.

"Why change passwords when you've got a baseball bat?"

Titan stick insects. An exceptionally big one might be almost 30 centimeters, giving a wing span approaching half a meter. But it seems Malaysia might have the longest of all:

http://ufbir.ifas.ufl.edu/chap33.htm

Thanks. I figured it would be a stick insect of some sort. I did some poking around and found 25cm to be an upper limit on the length (including extended legs), but I think the wingspan is going to be considerably less than their total length. See here. The new species from Borneo, Phoebaticus chani Hennemann and Conle, 2008, appears to measure out around 55-57 cm in total length. I'll have to see if I can get the Zootaxa article to see if the authors include wing length measurements.

Still, these are some seriously big bugs! They make our puny little North American stick insects look like stunted twigs in comparison.

Here is scientific discussion concerning the difficultly of Argentina Magnificens fight. A.M.'s wing span was 7m and it was estimated to have weighed roughly 70 to 72 kg which is three times heavier the heaviest current bird the Great Kori Bustard, which has great difficulty taking off. (Kori Bustard must run into a head wind.)

The authors postulate that the Argentina Magnificens could not take off on its own power, but need a slope and a strong head wind.

http://www.pnas.org/content/104/30/12398.full.pdf+html

There does seem to be an issue with larger and larger flying animals. Compare Argentina Magnificens to Quetzalcoatlus.

Estimates of pterosaur mass.

http://www.flickr.com/photos/markwitton/1386125619/