[Titanscape (OP)]

Long ago the dinosaurs became extinct, they were known to have small kinds of lungs. Perhaps the Earth's polarity changed over weakening the magnetosphere at the time resulting in the loss of atmosphere due to solar winds and storms, further resulting in the deaths of small lunged animals in a thinner atmosphere.

[Ophiolite]

Long ago the dinosaurs became extinct, they were known to have small kinds of lungs.

They were? Could you provide links that support this statement please.

Perhaps the Earth's polarity changed over weakening the magnetosphere at the time

There is no evidence of a polarity reversal at that time, therefore it is highly unlikely that one occured.

resulting in the loss of atmosphere due to solar winds and storms

There is no evidence that there is significant atmospheric loss during a polarity reversal. There is evidence that no significant changes in atmospheric pressure have occured in geologically short time frames.

So apart from the facts that dinosaurs did not have small lungs, polarity reversals don't lead to significant atmosphere loss and no polarity reversal occured at the time of the dinosaurs demise, apart from these things, it's not a bad idea.

[LeeE]

I don't think any of the current hypotheses re the CT extinction are complete because none of them explain why it seems to have especially targeted dinosaurs and not all life, both on land and in the oceans and seas.  There were plenty of marine dinosaurs too, along with the sharks and other fish, but only the marine dinos seem to have been wiped out.

To be honest, some sort of disease strikes me as the best explanation, with other animals that had evolved far away enough from the dinos not being susceptible to it.  I don't think there's any evidence to back any of that up, although there are some strange things in the general genetic make up of all animals today that seem both ancient but without apparent purpose.  Sorry, but I can't give any references about these; it's just stuff I remember reading about some time ago.

[Titanscape (OP)]

Physiology

With such a large body mass, combined with a long neck, physiologists encounter problems determining how these animals managed to breathe.

Beginning with the assumption that Apatosaurus, like crocodilians, did not have a diaphragm, the dead-space volume (the amount of unused air remaining in the mouth, trachea and air tubes after each breath) has been estimated at about 184 liters for a 30 ton specimen.

Its tidal volume (the amount of air moved in or out during a single breath) has been calculated based on the following respiratory systems:

    * 904 liters if avian
    * 225 liters if mammalian
    * 19 liters if reptilian.

On this basis, its respiratory system could not have been reptilian, as its tidal volume would not have been able to replace its dead-space volume. Likewise, the mammalian system would only provide a fraction of new air on each breath. Therefore, it must have had either a system unknown in the modern world or one like birds, i.e. multiple air sacs and a flow-through lung. Furthermore, an avian system would only need a lung volume of about 600 liters compared to a mammalian requirement of 2,950 liters, which would exceed the available space. The overall thoracic volume of Apatosaurus has been estimated at 1,700 liters allowing for a 500-liter, four-chambered heart (like birds, not three-chambered like reptiles) and a 900-liter lung capacity. That would allow about 300 liters for the necessary tissue. Assuming Apatosaurus had an avian respiratory system and a reptilian resting-metabolism, it would need to consume only about 262 liters (69 gallons) of water per day.[17]

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This site also says that the Jurassic period was quite from polarity shifts.

But I only bring this up amidst the present beginning of a shift. Not to propose a new theory. I can accept that there may not have been one at the extinction of the dinosaurs. But they were a lot over the millions of years spans.

[LeeE]

That all seems to assume that all dinosaurs were large; they were not.

[Ophiolite]

Your post is filled with inaccuracies and misunderstandings.

With such a large body mass, combined with a long neck, physiologists encounter problems determining how these animals managed to breathe.

1. Dinosaurs came in a wide range of sizes, from smaller than a chicken to giants of the kind that you seem to think represent all dinosaurs. So your contention that dinosaurs had a large body mass is wrong.
2. Only a subset of the larger dinosaurs had a long neck. So your contention that dinosaurs had long necks is wrong.
3. Just because physiologists have trouble figuring out how they breathed this does not mean that they actually had any difficulty in breathing. Don't you think such a difficulty might have shown up in the several tens of millions of years before their extinction?
4. You have taken the quotation out of context. (Indeed you failed to make clear that your entire first four paragraphs, plus four bullet points is copied from the wikipedia article.)
5. Your quoted passage offers a perfectly rational explanation for how the apatosuarus dinosaurs breathed - i.e. they used an avian system. So your quote fails utterly to support yout contention.
6. Finally the apatosaurs died out long before the end Cretaceous extinction of the dinosaurs in general.

I can summarise the previous observations by saying your research is woeful and fails utterly to support a rather silly idea.

You then provide some information on geomagnetic reversals. The information, from a cursory glance, appears to be correct, but it has no relevance whatsoever to your claims.

There was not a reversal coincident with the demise of the dinosaurs.
There is no evidence that reversals lead to a decrease in atmospheric pressure.
There is no evidence that dinosaurs were generally small lunged.
Those few dinosaurs that arguably had 'small lungs' a) had no difficulty breathing for millions of years, b) died out tens of millions of years before the KT extinction.

Please do yourself a favour and abandon this nonsense.

[Bored chemist]

The records show many reversale but few extinctions.
If one of the reversala killed the dinosaurs how come the other's didn't cause mass extinctions?

[Titanscape (OP)]

Merely speculating on a topic about which I know very little.

Speculating also about solar storms. Just speculation.

[Ophiolite]

Merely speculating on a topic about which I know very little.

Speculating also about solar storms. Just speculation.

On reflection, then, do you think it would have been better to have posted it in New Theories, in On the Lighter Side?

I would not have dismantled your argument with such ferocity if it had appeared there as clear speculation.