Dinosaurs

[David Levy]

Why all the dinosaurs have disappeared?

 

Dinosaurs were cold blooded. Hence,they had a very efficient energy consumption (they did not have to waste unnecessary energy heating their bodies). Therefore, they were able to reach huge size. It's quite clear that if they were hot-blooded, they would probably reach a maximal size of elephant... A sun light was needed to charge their power. Some had developed huge blood radiators panels on their back in order to get a fast heat charger. Those panels also gave them the ability to stay the whole day long in the lake and still achieve the heat which is needed for their body function. A crocodile for example, can't stay more than about three hours in the water. National Geographic don't understand the meaning of those heating panels till this moment.

 

Well, the asteroid impact had created darkness for a long period. Therefore dinosaurs lost their ability to function andactually died of starvation. The only survivors from the cold blood must have developed in the past the ability to fast for quite long period - such as crocodiles and certain reptiles (as they are the wizards of strategy -"Wait for food to come in your mouth"). Obviously, the majority of the survivals were hot blooded. Those animals were relatively small in size because they had to hide from the mighty dinosaurs. They could mainly obtain their food at night.Therefore, they had to develop a warm-blooded system.

 

A few year ago, a fossil dinosaur which is quite similar to turkey (with feathers) had been found in China. The feathers are evidence that it was a hot blooded dinosaur. Later on the feathers had been used for flying (as now he had to protect his life from the new mammalian predators). This dinosaur became the father of the birds. Therefore, we should thank this dinosaur for giving us a boiled egg and chicken schnitzel...

 

Edited June 1, 2012 by David Levy

[Nathan Flinn]

First of, dinosaurs survived (as birds). So that clears this subject.

 

Now, we don'd know if the great dinosaurs (those that did not make it) were "cold blooded" (ectotherms) or weather they could regulate their body temperature from within (endotherms). The latter is more likely. You are right that energy is spent on maintaining constant body temperature but energy is also saved because all the enzymes work more efficiently at their optimal temperature. Moreover, endotherms have a greater felxibility of behavior and migration.

 

It turns out that bigger animals are more likely to go endotherm (has to do with surface-volume ratio and some other reasons we can discuss elsewhere). Two examples of large almost endotherms: tuna fish, salt water crocodile. Both had been classically thought of as ectotherms. Turns out they can regulate their body temperature from within. (Ever tried a sushimi directly from the boat? Well, you should )

[Moontanman]

Why all the dinosaurs have disappeared?

 

As you point out we still have birds so all the dinosaurs didn't die out.

 

 

Dinosaurs were cold blooded. Hence,they had a very efficient energy consumption (they did not have to waste unnecessary energy heating their bodies).

 

Actually large bodies are easier to keep warm, in most keeping cool is more of a problem.

 

Therefore, they were able to reach huge size. It's quite clear that if they were hot-blooded, they would probably reach a maximal size of elephant...

 

Quite clear to who?

 

A sun light was needed to charge their power. Some had developed huge blood radiators panels on their back in order to get a fast heat charger.

 

There is considerable debate about this, the "blood radiators" could have been used to shed heat not pick it up and they could have been sexual displays as well.

 

Those panels also gave them the ability to stay the whole day long in the lake and still achieve the heat which is needed for their body function.

 

Which dinosaurs spent the day in a lake?

 

A crocodile for example, can't stay more than about three hours in the water.

 

Not to put too fine a point on this, but that is Bullshit

 

National Geographic don't understand the meaning of those heating panels till this moment.

 

Please show some support for this assertion and then explain why a popular magazine means anything in the realm of science to start with?

 

Well, the asteroid impact had created darkness for a long period. Therefore dinosaurs lost their ability to function andactually died of starvation.

 

I guess the death of plants had nothing to do with it?

 

The only survivors from the cold blood must have developed in the past the ability to fast for quite long period - such as crocodiles and certain reptiles (as they are the wizards of strategy -"Wait for food to come in your mouth").

 

This only makes sense if you assume that all large dinosaurs were cold blooded, this is almost certainly not true.

 

 

Obviously, the majority of the survivals were hot blooded.

 

Again, this is not a widely accepted idea, please show some support for this.

 

Those animals were relatively small in size because they had to hide from the mighty dinosaurs. They could mainly obtain their food at night. Therefore, they had to develop a warm-blooded system.

 

This of course ignores all the nocturnal dinosaurs as well as modern nocturnal reptiles...

 

A few year ago, a fossil dinosaur which is quite similar to turkey (with feathers) had been found in China.

 

Similar to a turkey in what way?

 

The feathers are evidence that it was a hot blooded dinosaur. Later on the feathers had been used for flying (as now he had to protect his life from the new mammalian predators).

 

Horse feathers, this "bird like dinosaur did not live in anymore danger of mammalian predators than any other dinosaur did at the time, which by the way was something like 100 million years before mammals were a threat to anything but insects...

 

This dinosaur became the father of the birds. Therefore, we should thank this dinosaur for giving us a boiled egg and chicken schnitzel...

 

Possibly, then again it could have just been a dinosaur with feathers, since quite a few non avian dinosaurs had feathers.

[Nathan Flinn]

Some had developed huge blood radiators panels on their back in order to get a fast heat charger.

 

Those were not dinosaurs. They came from the other branch of amniotes (Synapsida), which includes modern mammals (and not much more). Also, I agree with Moontanman that the function of those structures was probably to get rid of heat (or display).

[Ophiolite]

Dinosaurs were cold blooded.

While some dinosaurs were cold blooded there is good evidence that some of them were warm blooded.

 

For example this paperexplaining how oxygen isotope ratios point to homeothermy in theropod dinosaurs.

 

The situation is open to debate, but an unequivocal statement that they were cold blooded is out of place.

[Moontanman]

I think it should be pointed out that cold blooded is really far too inaccurate to mean anything. Endothermic and exothermic is a better metric but as characterized in the OP mammals are not all warm blooded. Some mammals vary their body temperatures on a daily basis as many as 30 degrees (some birds do as well), some mammals body temps are pretty much the same as their surroundings, others are far higher.

 

Elephants were listed in the OP somehow as big as land mammals can be when in fact there have been mammal's bigger than elephants by quite a bit.

 

http://www.msnbc.msn.com/id/40373523/ns/technology_and_science-science/t/dinosaur-die-off-cleared-way-gigantic-mammals/

 

Elephants, due to their large size and the fermenting vegetation in their large stomachs can be said to be endothermic but they have many similarities to gigantotherms in reality. Elephants are not good at maintaining their body temps and their closest living relatives the Hyrax while quite small still retain this characteristic.

 

http://en.wikipedia.org/wiki/Hyrax

 

Hyraxes retain a number of early mammalian characteristics; in particular, they have poorly developed internal temperature regulation (which they deal with by huddling together for warmth, and by basking in the sun like reptiles).

 

Sauropod dinosaurs were probably giganto-therms, the gigantic vats of fermenting vegetation that were their stomachs no doubt produced large amounts of heat, enough for them to live near the poles. The very active theropod dinosaurs were probably closer to bird endothermy or mammal endothermy than the giant sauropods and if you consider the wide range of endothermy in mammals it's not difficult to see that dinosaurs might have been endothermic across a wide spectrum as well. One thing that is certain is that dinosaurs did live in cold areas, yes the very large and the very small and to categorize them as cold blooded or warm blooded is far too simplistic.

 

On a side note, if indeed dinosaurs required sunlight to warm up so they could live think of how long a 50 ton monster would have had to bask to raise it's body temps just a few degrees... a few days of cold rain would be enough to make them completely torpid and easy prey for endothermic carnivores until they warmed up, a process that could take days...

[David Levy]

Cold Blooded or Hot Blooded Dino...

 

Lets compare it to the known animal based on size and diet.

 

1. Mammoth Size - Wikipedia "Like their modern relatives, mammoths were quite large. The largest known species reached heights in the region of 4 m (13 ft) at the shoulder andweights up to 8 tonnes (9 shorttons), while exceptionally large males may have exceeded 12 tonnes (13short tons)".

 

The Mammoth was bigger than the elephant. It is known that thisanimal lived in very cold aria. Hence, I assume that it's quite difficult to support so big size and still control the temp. Anyhow, even the Mammoth (as the biggest hotblooded animal) is tinny comparing the huge dinosaurs. Hence, There is no possibility to hot blooded animal to reach the Dino size, unless it's a cold blooded (Or living in a freezing water...).

 

2. CrocodileDiet - Hebrew version of Wikipedia "Diet - The crocodile is a supper predator… It feeds on small insects to buffalo, and its annual consumption is a tenth of theaverage meat consumption of a lion, so the bison filling the alligator for afew months. Because the slow metabolism of the crocodile enough, it can fastfor two months on average. It can also fast for the whole winter time".

 

Hence, a cold blooded animal can gain a hugesize comparing its diet to hot blooded animal.

 

Therefore, a cold blooded dinosaur might eat even less than an elephant and still gain a huge size.

Edited June 12, 2012 by David Levy

[Moontanman]

Cold Blooded or Hot Blooded Dino...

 

Lets compare it to the known animal based on size and diet.

 

1. Mammoth Size - Wikipedia "Like their modern relatives, mammoths were quite large. The largest known species reached heights in the region of 4 m (13 ft) at the shoulder andweights up to 8 tonnes (9 shorttons), while exceptionally large males may have exceeded 12 tonnes (13short tons)".

 

The Mammoth was bigger than the elephant. It is known that thisanimal lived in very cold aria. Hence, I assume that it's quite difficult to support so big size and still control the temp. Anyhow, even the Mammoth (as the biggest hotblooded animal) is tinny comparing the huge dinosaurs. Hence, There is no possibility to hot blooded animal to reach the Dino size, unless it's a cold blooded (Or living in a freezing water...).

 

2. CrocodileDiet - Hebrew version of Wikipedia "Diet - The crocodile is a supper predator… It feeds on small insects to buffalo, and its annual consumption is a tenth of theaverage meat consumption of a lion, so the bison filling the alligator for afew months. Because the slow metabolism of the crocodile enough, it can fastfor two months on average. It can also fast for the whole winter time".

 

Hence, a cold blooded animal can gain a hugesize comparing its diet to hot blooded animal.

 

Therefore, a cold blooded dinosaur might eat even less than an elephant and still gain a huge size.

 

 

So you didn't bother to even look at the links i provided? Dinosaurs were not "cold blooded", they were not crocodiles, predatory dinosaurs did not hang out in swamps waiting for a kill to come to them they were active predators that suppressed "warm blooded" mammals for something like 150 million years.

 

Whales show you are incorrect, "warm blooded" whales have to eat vast quantities of food to maintain their body heat but they still out grow all cold blooded sea vertebrates.

 

This is not a black and white thing, warm blooded and cold blooded are far too inaccurate to apply to mammals or dinosaurs... and as my link showed there have been land mammals much larger than elephants... larger in fact than many dinosaurs... and dinosaurs did indeed live in the polar regions which even back then did indeed experience protracted periods of darkness and cold, ice and snow...

[Arete]

I assume that it's quite difficult to support so big size and still control the temp. Anyhow, even the Mammoth (as the biggest hotblooded animal) is tinny comparing the huge dinosaurs. Hence, There is no possibility to hot blooded animal to reach the Dino size, unless it's a cold blooded (Or living in a freezing water...).

 

The blue whale is an endortherm:

 

And lives in both warm and cold oceans:

[Moontanman]

Since it was obviously ignored by the OP here is another illustration...

 

 

 

The largest land mammals that ever lived, Indricotherium and Deinotherium, would have towered over the living African Elephant, as shown in this diagram image provided by the journal Science.

 

The Indricotherium towered over mammoths and even many dinosaurs, it was more than 4.5 meters at the shoulder, it's head would have towered to well over 5 meters....

 

Anyhow, even the Mammoth (as the biggest hotblooded animal) is tinny comparing the huge dinosaurs. Hence, There is no possibility to hot blooded animal to reach the Dino size, unless it's a cold blooded (Or living in a freezing water...).

 

 

As the illustration shows the mammoth was not the largest land mammal. In fact not even close, being considerably out sized by another elephants relative and a rhinoceros relative as well...

Edited June 12, 2012 by Moontanman

[Nathan Flinn]

Therefore, a cold blooded dinosaur might eat even less than an elephant and still gain a huge size.

 

You insist on using terms that some of us here explained are inaccurate. A snake is "cold blooded" yet its blood can be warmer than yours when she is bathing in the sun. In fact many "cool blooded" animals can regulate their body temperature to a quite narrow range by modifying their behavior.

 

But this is not your biggest problem. You seem to push the idea that very low metabolism can allow an animal to grow bigger. This is not completely wrong but it is rather rare. You mention crocodiles. As I have pointed out already, salt-water crocodiles can to a large extend regulate their temperature from within, so they are endotherms, or "warm blooded" (well, almost). So even this, carefully picked example by you, has some issues.

 

Overall it seems that most if not all dinosaurs were endotherms (the jury is still out there). The amount of food they had to eat to maintain that status explains why the "nuclear winter" following the catastrophic meteor hit was so detrimental to them. I think the explanatory power of this view is stronger than what you are pushing. BTW: There is good evidence that many dinosaurs sat on their eggs (not unlike modern birds). Why would that work if they were "cold blooded"?

 

It is not clear why birds made it. Could be that their small size and living in the trees (safe from mammalian predictors) was a niche taken from other dinosaurs (many of whom were small but did not occupy the trees). There are many "hypothesis generating" speculations out there. Some interesting some less so.