An impact, the massive eruptions?
I've been studying dino skeletons and suggested metabolisms. We know now that some at least were warm blooded, that implies a fairly active life style which also implies either a 3 chamber heart or more likely a four chamber heart, either of which raises a problem.
No diaphram.
Modern mammals have a short rib cage, herbivorous dinos had a 'long' rib cage, with out which they could not have grown so large, but this creates a problem, with breathing!
These facts together, with other clues, suggests an atmosphere with a higher level of oxygen than to today, so what effects would the hundred of years of atmosperic pollution from the Traps have had on Dinos, is this perhaps why they died out but mammals with their diaphrams did not?
Roy.
Dino deaths.
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Dino deaths.
First people deny a thing, then they belittle it, then they say it was known all along! Von Humboldt
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circumspice
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Re: Dino deaths.
You pose a good question Dig. After some thought on the matter, I began to wonder if maybe non avian dinosaurs were perhaps more susceptable to air quality issues.
After all, the avian species of dinosaurs survived & eventually evolved into birds, right? (Yes, I know that birds were present before the dinosaurs went extinct)
So I looked up bird respiration & found some interesting facts:
The respiratory system of birds is more efficient than that of mammals, transferring more oxygen with each breath. This also means that toxins in the air are also transferred more efficiently.
This is one of the reasons why fumes from teflon are toxic to birds, but not to mammals at the same concentration. (like a canary in a coal mine?) <--- my comment
When comparing birds and mammals of similar weight, birds have a slower respiratory rate.
Link: http://www.peteducation.com/article.cfm ... 9&aid=2721
One of the implications is that the mammalian species that survived the K-T extinction event did so because of their inefficient mode of respiration.
So, if all that is true... How or why did birds survive???
Another question... Why did many reptilian species also survive?
After all, the avian species of dinosaurs survived & eventually evolved into birds, right? (Yes, I know that birds were present before the dinosaurs went extinct)
So I looked up bird respiration & found some interesting facts:
The respiratory system of birds is more efficient than that of mammals, transferring more oxygen with each breath. This also means that toxins in the air are also transferred more efficiently.
This is one of the reasons why fumes from teflon are toxic to birds, but not to mammals at the same concentration. (like a canary in a coal mine?) <--- my comment
When comparing birds and mammals of similar weight, birds have a slower respiratory rate.
Link: http://www.peteducation.com/article.cfm ... 9&aid=2721
One of the implications is that the mammalian species that survived the K-T extinction event did so because of their inefficient mode of respiration.
So, if all that is true... How or why did birds survive???
Another question... Why did many reptilian species also survive?
"Nothing discloses real character like the use of power. It is easy for the weak to be gentle. Most people can bear adversity. But if you wish to know what a man really is, give him power. This is the supreme test." ~ Robert G. Ingersoll
"Damn with faint praise, assent with civil leer, and, without sneering, teach the rest to sneer." ~ Alexander Pope
"Damn with faint praise, assent with civil leer, and, without sneering, teach the rest to sneer." ~ Alexander Pope
Re: Dino deaths.
Which would have given birds an advantage, the Crocodilia have four chambered hearts, which is less efficient than the four chambered hearts of mammals and birds, so if the Crocs could survive the smaller birds and mammals would also survive.The respiratory system of birds is more efficient than that of mammals, transferring more oxygen with each breath.
The question then arises as to what did the larger dinos have? Two, three or four chambers?
None of the larger Dinos needed a four, or even three chambered organ as non apparently were long distance runners, with them gone any Dino predators would have followed suit.
Right or wrong, I know not, but it does explain the selectiveness of the extinction.
Roy.
First people deny a thing, then they belittle it, then they say it was known all along! Von Humboldt
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circumspice
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Re: Dino deaths.
I remember reading a few years ago that paleontologists had discovered a therapod dino with fossilized internal organs in the thorasic cavity... specifically a heart.Digit wrote:Which would have given birds an advantage, the Crocodilia have four chambered hearts, which is less efficient than the four chambered hearts of mammals and birds, so if the Crocs could survive the smaller birds and mammals would also survive.The respiratory system of birds is more efficient than that of mammals, transferring more oxygen with each breath.
The question then arises as to what did the larger dinos have? Two, three or four chambers?
None of the larger Dinos needed a four, or even three chambered organ as non apparently were long distance runners, with them gone any Dino predators would have followed suit.
Right or wrong, I know not, but it does explain the selectiveness of the extinction.
Roy.
I wonder if they were able to get a good idea of the structure of its heart???
"Nothing discloses real character like the use of power. It is easy for the weak to be gentle. Most people can bear adversity. But if you wish to know what a man really is, give him power. This is the supreme test." ~ Robert G. Ingersoll
"Damn with faint praise, assent with civil leer, and, without sneering, teach the rest to sneer." ~ Alexander Pope
"Damn with faint praise, assent with civil leer, and, without sneering, teach the rest to sneer." ~ Alexander Pope
Re: Dino deaths.
They did, it was four chambered...
http://www.google.co.uk/url?sa=t&rct=j& ... 5Q&cad=rja
the animal was also way above the body weight of those that survived, which apparently was about 100 pounds. The cut off at that weight must be significant, but how? It has been suggested that those below that weight could have hibernated, but what could have wiped out the heavier animals and then passed in sufficiently short a period that hibernaters could have survived it?
Roy.
http://www.google.co.uk/url?sa=t&rct=j& ... 5Q&cad=rja
the animal was also way above the body weight of those that survived, which apparently was about 100 pounds. The cut off at that weight must be significant, but how? It has been suggested that those below that weight could have hibernated, but what could have wiped out the heavier animals and then passed in sufficiently short a period that hibernaters could have survived it?
Roy.
First people deny a thing, then they belittle it, then they say it was known all along! Von Humboldt
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circumspice
- Posts: 1201
- Joined: Sat Dec 19, 2009 7:10 pm
Re: Dino deaths.
I followed several of the links on the page you linked... The interpretation of the object claimed to be a fossilized heart is hotly contested.Digit wrote:They did, it was four chambered...
http://www.google.co.uk/url?sa=t&rct=j& ... 5Q&cad=rja
the animal was also way above the body weight of those that survived, which apparently was about 100 pounds. The cut off at that weight must be significant, but how? It has been suggested that those below that weight could have hibernated, but what could have wiped out the heavier animals and then passed in sufficiently short a period that hibernaters could have survived it?
Roy.
Although CT imagery of the concretion has revealed internal cavities reminiscent of the ventricular chambers of a four-chambered heart, the object exhibits none of the other anatomical structures of an actual heart. Its supposed ventricular portion engulfs the eleventh rib and lies partly outside of the thoracic cavity.
The article goes into extreme detail, point for point, in order to refute the assertion that the object is indeed a fossilized heart.
Here is a link for the remainder of the article: http://www.sciencemag.org/content/291/5505/783.full
Honestly... I wish the 'experts' could, just once, agree on something... anything...
"Nothing discloses real character like the use of power. It is easy for the weak to be gentle. Most people can bear adversity. But if you wish to know what a man really is, give him power. This is the supreme test." ~ Robert G. Ingersoll
"Damn with faint praise, assent with civil leer, and, without sneering, teach the rest to sneer." ~ Alexander Pope
"Damn with faint praise, assent with civil leer, and, without sneering, teach the rest to sneer." ~ Alexander Pope
Re: Dino deaths.
That'll be the day! 
I suspect that the faster predators had a 4CH but as I said earlier the big herbivores would seem to have gained little from such, having said that their arteries must have been made of concrete! And something must have stopped them from 'redding out' when they lowered their heads.
Roy.
I suspect that the faster predators had a 4CH but as I said earlier the big herbivores would seem to have gained little from such, having said that their arteries must have been made of concrete! And something must have stopped them from 'redding out' when they lowered their heads.
Roy.
First people deny a thing, then they belittle it, then they say it was known all along! Von Humboldt
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circumspice
- Posts: 1201
- Joined: Sat Dec 19, 2009 7:10 pm
Re: Dino deaths.
I remember speculations from many years ago that the large sauropods 'may' have had 2 brains to handle operating such a large body...Digit wrote:That'll be the day!
I suspect that the faster predators had a 4CH but as I said earlier the big herbivores would seem to have gained little from such, having said that their arteries must have been made of concrete! And something must have stopped them from 'redding out' when they lowered their heads.
Roy.
Actually, it was supposed to be a nexus point, where important nerves converged, in the hip area, and it supposedly cut the distance that
nerve impulses had to travel by about half, facilitating and/or speeding the transmissions in both directions...
Ditto for a possible second 'heart'... Supposedly an enlarged artery that could help with the flow of blood to remote parts of the body.
But that was all fanciful speculation, nothing more.
"Nothing discloses real character like the use of power. It is easy for the weak to be gentle. Most people can bear adversity. But if you wish to know what a man really is, give him power. This is the supreme test." ~ Robert G. Ingersoll
"Damn with faint praise, assent with civil leer, and, without sneering, teach the rest to sneer." ~ Alexander Pope
"Damn with faint praise, assent with civil leer, and, without sneering, teach the rest to sneer." ~ Alexander Pope
Re: Dino deaths.
Simple organisms have no true heart, just a pulsing artery to squeeze the blood along, so a secod 'heart' is feasible.
We have one way valves in our veins to stop blood pooling in our legs, such in the neck would have helped the load on the heart with the long necked sauropods, but wouldn't have helped if they lowered their heads, so their circulatory systems may well have been unique.
Roy.
We have one way valves in our veins to stop blood pooling in our legs, such in the neck would have helped the load on the heart with the long necked sauropods, but wouldn't have helped if they lowered their heads, so their circulatory systems may well have been unique.
Roy.
First people deny a thing, then they belittle it, then they say it was known all along! Von Humboldt