Loch Ness Monster?

[Gilded]

Dang. :> What is it with the Brittish and fun spoiling? >:/

[Ophiolite]

We still resent the loss of our Empire.

[YT2095]

We still resent the loss of our Empire.

Good Answer! )))

 

however my motivation is somewhat more mundane, to ME the idea I presented seems to be the most Logical/Rational of all pressented thus far.

and with the lack of data provided, using the KNOWN data is the only option.

 

I base mine on opinion only (seriously, that`s all it is!) plausable... I think so

 

and it certainly seems to make a hell of alot more sense! whether I`m right or wrong

[LucidDreamer]

We still resent the loss of our Empire.

Don't worry. We are forming our own in the spirit of imperialism. We will let you live vicariously through us and we will throw you a few scraps here and there.

 

Because we can,

The United States

[Ophiolite]

And don't think we don't appreciate it. The current waves of anti-Americanism in the UK are simply an amusing ploy on our part to make Tony Blair feel paranoid and unloved.

 

 

Back on topic: YT if you scroll back to an earlier post (#19) you will see I refer to a guy in the 60s promoting the decaying vegatable matter explanation.

[YT2095]

aha! so you did!

 

then there`s 2 of us in agreement

[Mokele]

Personally, I don't see how it's possible that all the dinosaurs died out during the K-T extinction.

 

And? Dinosaurs weren't aquatic. Some may have been able to paddle around a bit, but the large aquatic reptiles of the mesozoic were not dinosaurs, nor even archosaurs of any form. Technically, they were less closely related to dinosaurs than modern crocs are.

 

As such, they were almost definitely cold-blooded, which makes the highly unlikely candidates for Loch Ness. Also, they tended to be shallow-water organisms, or at least those we know of were. That and the fact they're incredibly common in the fossil record, and then suddenly become absent 65mya, which gives a pretty good indicator of "they're all dead".

 

----------

 

Also, I should point out that, while I personally think it's a combination of unusual waves and rotten logs, the intention of the thread was a kind of fun, hypothetical "What if...". As in, *if* something was indeed down there, what would it be?

 

My money would be on an extremely large salamader, possibly a cryptobranchid (like the america hellbender and Japanese and Chinese giant salamanders). They can survive in very cold water, respire through their skin, have a low metabolism and thus low food requirements, and typically spend most of their time laying on the bottom where they're well camoflaged, less by any pressure for direct camoflage and more by the fact they look more like an wrinkly sausage. On top of that, as fans of the Carboniferous and Permian know, amphibians can reach some very substantial sizes, given the right selective pressures. Coupled with people's tendency to overestimate the size of big animals (especially herps), something merely twice the size of a Japanese giant salamander would do the trick, I think.

 

And, as I said, this is all hypothetical "what if it wasn't just rotting logs" stuff, for the fun of it.

 

Mokele

[Artorius]

And? Dinosaurs weren't aquatic. Some may have been able to paddle around a bit' date=' but the large aquatic reptiles of the mesozoic were not dinosaurs, nor even archosaurs of any form. Technically, they were less closely related to dinosaurs than modern crocs are.

 

As such, they were almost definitely cold-blooded, which makes the highly unlikely candidates for Loch Ness. Also, they tended to be shallow-water organisms, or at least those we know of were. That and the fact they're incredibly common in the fossil record, and then suddenly become absent 65mya, which gives a pretty good indicator of "they're all dead".

 

Mokele[/quote']

Coelacanth seems happy enough swimming around with other fisheeez.And the fossil record which seems large is in fact very miniscule. So although we refer to it, in reality its like the first page of a 360 page book with 355 unread

[Mokele]

Coelacanth seems happy enough swimming around with other fisheeez.

 

True, and i didn't say that just because we have no fossils, there aren't any. But still, you must admit that exceptions like the coelocanth are rare, and that, in general, most things that vanish from the fossil record truly are gone. So, while them vanishing from the fossil record doesn't *prove* it, it gives a pretty high probability.

 

So although we refer to it, in reality its like the first page of a 360 page book with 355 unread

 

I think a better analogy is a book where 199 out of every 200 words are blacked out, mostly randomly. If we stop seeing 'dog' maybe the dog is gone. It doesn't prove it, of course, but as best we can tell it's the best guess.

 

 

Of course, all of that is moot, since a plesiosaur would likely just freeze to death in Loch Ness.

[atinymonkey]

It's not really moot, unless you can prove the plesiosaur was cold blooded.

[Artorius]

True, and i didn't say that just because we have no fossils, there aren't any. But still, you must admit that exceptions like the coelocanth are rare.

Yes about as rare as unknown creature reports from around the globe!!!

Just remember pre-1930's if anyone had published crap like they had caught a coelacanth but let it go.Well i dont have to elaborate on that fiasco.

 

They are many supposedly extinct or new animals turning up each yearby the way

[psi20]

http://www.ucmp.berkeley.edu/diapsids/metabolism.html

 

Not all dinosaurs and reptiles are ectothermic.

[Mokele]

It's not really moot, unless you can prove the plesiosaur was cold blooded.

 

Prove, no, but given that they diverged from diapsida before archosauria did, and that warmbloodedness evolved somewhere in archosauria (in accordance with parsimony), the chances of them being endothermic are excedingly slim.

 

Yes about as rare as unknown creature reports from around the globe!!!

 

Most of which are balloney. And even if they aren't, that's what, 200 species we thought were extinct but aren't? That's still a tiny fraction of the number of species in the fossil record. Hell, is we doubled the number of species we know, all from supposedly extinct lineages, we'd *still* be looking at 98% of what you see in fossils not being around anymore.

 

Not all dinosaurs and reptiles are ectothermic.

 

Firstly, plesiosaurs are not dinosaurs. They aren't even archosaurs. We have no indications that anything outside of archosauria ever evolved full endothermic homeothermy.

 

Secondly, most large dinosaurs, simply by virtue of their size, had a metabolism closer to a reptile than a mammal, as anything more would have cooked them in their own skin like a giant baked potato. An elephant's metabolism is about 0.08 L O2/kg/hr, while a leathback sea turtle's is 0.07 L O2/kg/hr. As you get larger and larger, the level of basal metabolism needed to maintain internal homeothermy is lower and lower. After a certain size, which is less than many dinosaurs, the distinction between mass homeothermy and endothermy vanish. Maybe some small ones had some degree of endothermy, but it makes no thermodynamic sense of the larger species.

 

But most importantly, I find it hard to believe an aquatic organism would evolve endothermy if not already present. The loss of heat to water is hundreds of times faster than air, making either lots of insultation or extremely high metabolism necessary.

 

We know that endothermy must have evolved somewhere inside Archosauria, since crocodiles are cold-blooded but birds aren't. In order for plesiosaurs to be warm blooded, it would have had to evolve twice in diapsid reptiles (once in archosauria and once in plesiosaurs). Given the lack of evidence or reason to consider endothermy, the most likely posibility is ectothermy.

 

Mokele

[Artorius]

Owing to the fact that its accepted that most dino's could move quite rapidly,they must have had a quite high metabolic rate.Given studies on modern animals,metabolic rate is proportional to rate of locomotion.And given the fact dino's like modern endotherms have erect postures,limbs under body not splayed out to sides is indicitive of endothermy.Given some dino's whos erect psture had a long vertical distance between head and heart which would require a high blood pressure.Given that some dino's had to compete with mammals for about 170million years you could equally infer that some of them were indeed warm blooded.Unless diplodocus was served with cheese from the local baked diplotato stand

[Mokele]

Owing to the fact that its accepted that most dino's could move quite rapidly,they must have had a quite high metabolic rate.

 

If that's so, why can the cuban crocodile run at over 20 mph? And I don't even want to guess how fast most lizards can go when you scale their body size to ours, but given that they've outrun me without any such benfit, I'd say pretty damn fast.

 

Speed has little to do with metabolic rate. Now, high metabolic rate *does* give increased endurance and higher aerobic scope, but burst speed is a whole different ball game.

 

The problem is that there's no way to know if something like a Velociraptor relied on burst speed or endurance without observing them directly, which is problematic on account of them all being dead.

 

Given studies on modern animals,metabolic rate is proportional to rate of locomotion.

 

Wrong, aerobic scope is, not burst speed. Show me a peer-review paper saying otherwise.

 

And given the fact dino's like modern endotherms have erect postures,limbs under body not splayed out to sides is indicitive of endothermy

 

Early crocodiles also had an erect limb stucture, and, unless you claim they evolved endothermy then lost it again, they were cold blooded. Many modern large lizards have a semi-erect gait, including my own pet, and they're definitely cold blooded.

 

You can't even effectively claim the problem is interference with respiration, and modern crocodilians not only have a semi-erect gait but a hepatic-pump ventilation system, and they're still cold blooded.

 

Given some dino's whos erect psture had a long vertical distance between head and heart which would require a high blood pressure.

 

And what precludes a reptile from generating high blood pressures?

 

Hell, one genus springs to mind that can generate blood pressures high enough to shoot blood from the capilaries around the eys for a distance of 6 feet. If a lizard with a heart the size of a pea can do that, what precludes a reptile from evolving to generate the blood pressures needed for a long neck?

 

Oh, plus skeletal evidence indicates that the museum mounts of brachiosaurs and diplodocids are wrong: The former likely could not raise their necks much above 45 degrees, and the latter could not raise their necks much over horizontal. This is based on joint articulations.

 

Given that some dino's had to compete with mammals for about 170million years you could equally infer that some of them were indeed warm blooded.

 

You know what the Wallace line is?

 

Ok, take a map of inonesia, and draw a line perpendicular to the island chain between Sulawesi to the southeast and the Phillipines, Borneo and Java on the northwest side of the line.

 

On the asian side of this line, there are very few marsupials, while on the australian side, there are no native placental mammals other than bats (though some have been introduced, sadly).

 

There's something else about this line, though: it represents a divide in the occupation of the niche of "small carnivore". On the side with placental mammals, they dominate that niche. But on the side with marsupials, they are absent from that niche. Who fills that niche?

 

Monitor lizards. Marsupials, which are barely different from placentals, cannot compete with ecotherms. Look at everywhere south of the Wallace line: most of the carnivores are what? Reptiles. Only at night or for herbivorous niches can marsupials compete.

 

What does this mean? That the "dominance" of placental mammals rests on a very narrow margin, and without that margin, the supposedly inferior reptiles outcompete the fuzzballs.

 

Now, given that placental mammals didn't even evolve until the mid-cretaceous, and at that time there were no availible niches for large organisms for them to evolve into, what does that say for your claim?

 

Endothermy is *clearly* not a requirement for outcompeting mammals.

 

Unless diplodocus was served with cheese from the local baked diplotato stand

 

This part is verifiable because it's simple thermodynamics. Heat is generated by an organism's cells, thus as the organism increases in linear dimensions, heat generated increases to the cube (more volume either means more cells, or more chemicals in those cells reacting, either of which means more heat per unit volume) However, heat is lost across the surface of an animal (or any object, actually). The surface area of an animal increases to the square of the animal's linear size increase.

 

Let's clarify with an example: Say I take a "giant pill" and grow to twice my current height, without any change in proportions (yes, I am aware that proportions *do* change, but this is to illustrate the underlying principle. That complicating factor can be adjusted for). Because I am twice my original height, I now have 8 times as much volume. That means I have 8 times as much heat generation. But my skin area (surface area) has only increased 4 times. So I'm generating heat 8x as fast as before, but only losing it 4x as fast. In short, when you increase in size linearly, your ratio of surface area to volume decreases linearly. A bit of basic math will verify this.

 

This is why, at the same ambient temperature, an elephant has a slower metabolism than a cow. In order to maintain a core body temperature of 98 degrees (or whatever it is for elephants), it needs to generate less heat per cell than a cow, because it has less surface area per kg of mass.

 

Now, we already know that an elephant's resting metabolism is not much higher than a reptile's, yet that low level of heat is sufficient to warm it because of the small surface area of volume ratio. So what about a sauropod which is twice the size of an elephant? It would have *half* the relative surface area per unit mass of an elephant, and thus half the heat dissipation capacity (ignoring special adaptations).

 

For the largest of sauropods, even with reptilian-level metabolisms their main problem would have been overheating, not cooling down.

 

Mokele

[JohnB]

Mokele, I"m not going to argue with you, as I can barely keep my nose above water following your explanations.

 

A question. How do the carnivorous marsupials fit into the picture? Did they come much later, or simply not a major player?

 

The two that come to mind are the Marsupial Lion (which I've been told was more than a match for the African Lion) and the Carnivorous Kangaroo. The second is a doozy, 10 foot tall, 00's of lbs and ran (hopped) at nearly the speed of a Cheetah.

 

Monitor lizards died out some 10,000 years ago we believe. (We could be wrong, there are still areas white man hasn't been to and Aboriginals won't go there. They generally say a Bunyip lives there.) These were bloody huge. 10 metres long or more. (There's one in the Queensland Museum, it's head is over a metre long.

 

As to Dinos of some description surviving in the ocean. Why not? There are plenty of accounts of "Sea Monsters" over the last 1,000 years. The reports of sightings dropped off in the modern era though. Could it simply be that they don't like the sound of propellors. Sailing ships were quiet, modern ships let every creature for 50 miles know they are coming.

 

I'm reminded of comments made as the Graf Zeppelin circumnavigated the world and crossed the Pacific; "We saw giant Sunfish and Whales and creatures the like we had never seen before". Considering the people on that flight, it was an unusual thing to say.

 

Before anybody accuses those sailors of being credulous fools or some such, remember that sailors have been telling of gigantic "Rogue Waves" for centuries too and the scientific community didn't believe them. Oops.

 

This is not to say that conventional scientific thought is always wrong, merely a reminder that it is not always right.

[LucidDreamer]

If that's so...

Excellent post Mokele. I agree with alot of what you said but I always find this argument a little strange. People seem to be arguing as to whether the dinosaurs had the same metabolism, body temperature regulation systems, and circulation systems of mammals or reptiles. As we all know the dinosaurs split off from the reptiles and mammals millions and millions of years ago. We also know that there are not really two distinct groups of ectotherms with slow metabolisms and endotherms with high metabolisms, but rather a range with all sorts of hybrid systems.

 

The dinosaurs probably did not have the same metabolisms, body temperature regulation systems, and circulatory systems as reptiles or mammals. Their closest living relatives are birds but it’s difficult to derive much information from them either because there was 65 million years of evolution and adaptation to flight.

 

I am fairly confident that the dinosaurs had circulatory systems and metabolisms greater than reptiles. Can you imagine a reptile the size of a brontosaurs roaming the countryside? You already pointed out that they would not require much heat production because of their size and that in fact they would have problems with heat reduction but what about circulation and respiration. A strong circulatory system would have been just as benificial to cooling as it is to heating an animal.

 

An animal that size would require an enormous amount of oxygen and an incredible circulatory system. Its possible that they developed some other means to help with their 3 chambered heart, but aves are the dinosaur's closest living relatives and they have 4-chambored hearts. A bird's circulatory system and its extremely efficient respiratory system would have been a great advantage to dinosaurs.

 

Also, the dinosaurs were small to enormous animals that roamed the earth. The larger ones spent alot of time in fairly open areas without an immediate place to hide. This means that they either had to fight predators or run away. It would have been incredibly beneficial to be able to run for a moderate amount of time. A reptile can sprint very well but it would run out of steam before it got halfway across the field.

 

There is some indication from the fossil evidence that some dinosaurs were migratory. Migration requires enormous amounts of endurance that reptiles don't have. There are probably some counter examples to this but as a general principle it holds up that migration would require a high metabolism with a highly developed circulatory and respiratory system.

 

Most of the points that I mentioned only indicate a high metabolism, which could be independent of endothermy. After all endothermy is usually just a bunch of fat tissue producing excess heat, at least in mammals. Endothermy requires a great deal of energy so you would have to conclude that any animal that lived in a cold climate but maintained a high body temperature would require a high metabolism. However, it doesn’t seem to me that a high metabolism would require Endothermy if the animal lived in a constantly warm environment.

 

However there is one thing I can think of that indicates that dinosaurs had some endothermic regulation. Some dinosaur fossils have been found in areas that are thought to have been quite cold. This is very strong evidence that some dinosaurs were endothermic.

[Artorius]

well said ,mokele thinks he can dismiss endothermic probabilty siting modern animals biology,when someone uses it to establish that after all it could be possible siting same.He states its fact that dinosaurs(large) could not have been endothermic!!

When from my standpoint all im trying to convey is we dont truelly know !so it is possible and we cannot rule out the possibility of such a creature in the loch.

Im not saying that there is a Nessie by the way.

[Mokele]

A question. How do the carnivorous marsupials fit into the picture? Did they come much later, or simply not a major player?

The two that come to mind are the Marsupial Lion (which I've been told was more than a match for the African Lion) and the Carnivorous Kangaroo. The second is a doozy, 10 foot tall, 00's of lbs and ran (hopped) at nearly the speed of a Cheetah.

 

Unfortunately, we don't really know how well they fit in, since reconstructing extinct ecosystems is problematic at best. We know how it is now, and in the historical past when we have direct records, but fossils are harder to deal with, especially since, for instance, we can't tell if those predators were nocturnal or diurnal. If they were nocturnal, it would mean they weren't competing with herps. Maybe they occupied a marginal niche, or occupied one that was left vacant by an extinction. It's hard to tell.

 

Monitor lizards died out some 10,000 years ago we believe. (We could be wrong, there are still areas white man hasn't been to and Aboriginals won't go there. They generally say a Bunyip lives there.) These were bloody huge. 10 metres long or more.

 

Um, not exactly.

 

Megalinia priscis (sp?), the 10 meter monitor lizard, did indeed die out about 10k years ago, so far as we know (I doubt something like that could survive unseen). However, modern monitor lizards are plentiful. You call them goannas, I believe. Everything from the Komodo dragon to those little spiny-tailed ones you have in rocks in the outback (Varanus acanthurus, a popular pet over here) is a monitor. IIRC, there are currently 50-odd species (but the taxonomy is a nightmare, and changes every time someone sneezes), all in one genus, Varanus.

 

Some modern monitors make good pets, too. Since you're in Australia, I'd reccommend the spiny-tails. I've not worked with my myself, but everyone says they're great animlas.

 

As to Dinos of some description surviving in the ocean. Why not?

 

Firstly, they'd have to evolve into an aquatic niche from purely terrestrial.

 

Technically, plesiosaurs, mosasaurs, ichthyosaurs, pliosaurs and the like weren't dinosaurs. Nor were the flying reptiles, pterosaurs. They were reptiles, but not dinosaurs. The sea-dwellers were diapsids that either diverged at the same time as archosaurs (crocs, dinos and birds) and lepidosaurs (modern snakes and lizards), or very shortly thereafter (but which they came from, if that's the case, is hotly debated). Archosaurs, in turn, had numerous subsequent diversions (including crocs and pterosaurs), and didn't produce the clade of dinosaurs until about 30+ million years after the sea-dwellers split off.

 

So, technically, even if someone found a living plesiosaur, there would still be no living non-avian dinosaurs.

 

This is not to say that conventional scientific thought is always wrong, merely a reminder that it is not always right.

 

Oh, of course. The oceans have who knows what in there. What I'm saying is that Ness is an unlikely spot for an animal that a) is probably extinct, b) was probably cold-blooded c) breathed oxygen and thus would have to surface frequently (even once a day would result in a lot more sightings).

 

As we all know the dinosaurs split off from the reptiles and mammals millions and millions of years ago. We also know that there are not really two distinct groups of ectotherms with slow metabolisms and endotherms with high metabolisms, but rather a range with all sorts of hybrid systems.

 

Well, two of the more recent theories I've found have been that a) dinosaurs were highly diverse, so expecting them to all use the same thermal strategy is a bit silly and b) if you extrapolate avian metabolism to something the size of a sauropod, you still get only 2x reptile metabolism at that size.

 

On top of that, even living systems have more gradation than we think. Large rattlesnakes can become endotherms with the metabolic heat generated from digestions of a large food item. Marsupial body temps fluctuate with temps, to a limited extent, and monotremes even moreso. Leatherback sea turtles are homeothermic.

 

Even the modern world has a huge range of thermal systems in animals, so why should we expect less of the dinos. Possibly the large ones had lower metabolisms than the small, or maybe it fell out along phylogeny.

 

Of course, the image that pops into my mind is that Far Side cartoon of the prof with a huge thermometer approaching the rear of a dinosaur with the caption "Moments later, the doctor and his time machine were obliterated, once again denying an answer to the question of warm blooded dinosaurs."

 

I am fairly confident that the dinosaurs had circulatory systems and metabolisms greater than reptiles. Can you imagine a reptile the size of a brontosaurs roaming the countryside? You already pointed out that they would not require much heat production because of their size and that in fact they would have problems with heat reduction but what about circulation and respiration. A strong circulatory system would have been just as benificial to cooling as it is to heating an animal.

 

Of course, but I don't agree that a strong circulatory system necessitates a high metabolism.

 

An animal that size would require an enormous amount of oxygen

 

In raw volume, yes, but with a reptilian level or near-reptilian (even 2x reptilian) metabolism, the oxygen demands and food demands would be suprisingly low on a per kg basis. Many even unspecialized (like not evolved for diving) large reptiles can go for hours on a single lungful of air.

 

Its possible that they developed some other means to help with their 3 chambered heart, but aves are the dinosaur's closest living relatives and they have 4-chambored hearts.

 

I should note that the inefficiency of the 3 chambered heart is an oversimplification that does not reflect reality. In actuality, there is very little mixing of blood in a reptile heart, due the the fluid dynamics of the system.

 

But, given that crocodiles and birds, the sister taxon and descendants respectively, both have the 4 chambered heart, it's pretty likely dinos did too. But, note that crocs have it, so endothermy isn't required.

 

its extremely efficient respiratory system would have been a great advantage to dinosaurs.

 

yes, but of course, that doesn't mean they had it. They may have had the precursors, though, like a sort of half-@$$ed intermediate. I know theropods and sauropods had air sac systems, but it's impossibile to tell if or how they were connected to the respiratory system.

 

The larger ones spent alot of time in fairly open areas without an immediate place to hide. This means that they either had to fight predators or run away. It would have been incredibly beneficial to be able to run for a moderate amount of time. A reptile can sprint very well but it would run out of steam before it got halfway across the field.

 

Except for one problem: "Run" wasn't going to happen for a sauropod. Their bones just plain could not take it. They could walk fast, like a modern elephant, but, like an elephant, an actual "run" was out of the question.

 

In fact, I've heard that a recent kinematic study showed the even T. rex was too large and heavy to perform what is kinematicly classed as a run. Of course, with such a huge stride length, it probably didn't have to in order to move fast.

 

Also, a large part of the reptilian endurance problem is the issue of lung function: lizards that wiggle from side to side can't breathe as they do so, because the lungs are being alternately compressed and expanded as the body bends, forcing air from one to the other rather than in or out. For a biped like a dinosaur, or even something with an erect gait, that ceases to be a constraint. Those modern reptiles with semi-erect gaits (monitors, crocodilians) show improved endurance, and snakes also show remarkable endurance due to the lack of any limb-constraints at all.

 

Of course, you are right that their endurance would have been lower, but that doesn't necessarily mean they were screwed. Standing and fighting was still a viable option, and from the fossils it seems like, with the exception of hadrosaurs, it was a very popular option.

 

There is some indication from the fossil evidence that some dinosaurs were migratory. Migration requires enormous amounts of endurance that reptiles don't have. There are probably some counter examples to this but as a general principle it holds up that migration would require a high metabolism with a highly developed circulatory and respiratory system.

 

Not necessarily. Most migration, at least as far as I know, is at walking pace. Such a pace is within the aerobic scope of reptiles and mammals.

 

While it's true that the only migratory reptiles are sea turtles, I suspect this has less to do with endurance than size: reptiles in areas where the climate varies enough to make migration a viable option are too small to make it viable (just as you'll notice that many small mammals don't migrate). After all, a mile is a lot longer to an anole than to a deer. Those that are big enough are usually in areas where climate doesn't fluctuate enough to make it worthwhile.

 

Some dinosaur fossils have been found in areas that are thought to have been quite cold. This is very strong evidence that some dinosaurs were endothermic.

 

Again, not necessarily. Even the poles had summers that were moderately warm in those days, and some could have avoided the cold by migrating. Others could have hibernated (in fact, there's evidence one of the small fabrosaurs did so). Their existence in such locales does not necessarily require endothermy: another polar denizen of those days was Koolasuchus, one of the last of the temnospondyl amphibians, existing in a niche similar to a crocodile.

 

Also, organisms exposed to cooler temperatures even within their own lifetime (including cold-blooded organisms like frogs) will increase their metabolism in response over the course of a few hours. For large animals like most dinosaurs, that individual environmental acclimation would have helped immensely, maybe enough to make permanent high metabolism moot.

 

After all endothermy is usually just a bunch of fat tissue producing excess heat, at least in mammals.

 

While many mammals have brown fat (the type you indicate), in most cases endothermy is simply the product of two things: a metabolism that simply runs faster than ectotherms, and a sort of internl, hormonal thermostat to finely tune it and keep it close to a pre-set core temp (I think it's the hypothalamus).

 

-----

 

I think my prof summarized the situation best: Nothing that is casually linked to endothermy fossilizes. Lots of things that are *correlated* do, but as we all know, correlation doesn't prove causation. The clues we *really* need rotted away long ago, leaving us to guess.

 

mokele thinks he can dismiss endothermic probabilty siting modern animals biology

 

You are misquoting me. I can argue, from evidence and thermodynamics, that it's less probable than some think, and that there is evidence against endothermy. In short, I contend that the debate over it is not as settled as many think, that there are legitimate arguements on both sides, and that the blanket assertion of the same metabolism for all dinosaurs is unlikely.

 

when someone uses it to establish that after all it could be possible siting same.

 

You think this is bad? Look into snake evolution. There's about 8 different theories, all based on the same evidence, both fossil and modern. Paleontology rarely has neat, simple, clear answers. That's what makes it both so frustrating and so fun.

 

He states its fact that dinosaurs(large) could not have been endothermic!!

 

Actually, no, my position is much more nuanced than that.

 

Endothermy simply means internally generated heat. But several organisms, like monotremes, have that but have body temps that vary (heterothermy). By contrast, ectotherms get most of their heat from the environment, but many have no significant variation in body temp (homeothermy; think of a tropical fish that's in perpetually warm waters). To further complicate matters, *all* living things generate heat internally, so the distinction is really about precisely how much they generate and where it goes.

 

And, as if that wasn't enough, as organisms increase in size, their surface area to volume ratio decreases, meaning they need less heat generation (lower metabolism) to sustain a high interior body temp than a smaller organism.

 

When you scale this up to the truly collossal sizes of sauropods, for example, you find that a metabolism running at reptilian or only slightly higher provides sufficient internal heat.

 

So, what I'm actually saying is that, when an animal gets as big as a sauropod, a reptilian level metabolism is sufficient to maintain a mammal-level core temperature, just due to the extremely low surface/volume ratio.

 

Is that endothermy? Well, it is internal heat generation. But it's also at a reptilian level metabolism, relying on sheer thermodynamic bulk, so is it mass homeothermy?

 

At extremely large scales, these distinctions we have break down.

 

so it is possible and we cannot rule out the possibility of such a creature in the loch.

 

It's possible, yes, but possible does not equal probable.

 

Mostly because we know that endothermy had to evolve in the lineage *somewhere* between where crocodiles (cold bloods) split and birds split. Somewhere in there, warm-blood evolved.

 

The proble with this for Nessie is that plesiosaurs branched off *before* then. Plesiosaurs were not dinosaurs, but a totally separate evolutionary line that's actually closer to snakes and lizards (in my opinion, though even if I'm wrong, the closeness isn't much reduced, as they diverged either at or shortly after lepidosaurs (snakes and lizards) split from archosaurs (crocs, dinos, birds)).

 

This means that if plesiosaurs *were* warm blooded, they would have had to evolve it in parrallel with the dinosaurs (if they were warm blooded). That's certainly possible, I agree, but I don't see any reason to suspect they would, either from theory or from the fossil evidence of them.

 

So, in my eyes, it's *possible* that plesiosaurs were endothermic, but not very likely.

 

Im not saying that there is a Nessie by the way.

 

Of course, not, neither is anyone here. This whole thing is intended to be a sort of "what if" game.

 

Mokele

[LucidDreamer]

Another excellent post mokele. You are a reptile and dinosaur god.

 

"Even the modern world has a huge range of thermal systems in animals, so why should we expect less of the dinos."

 

That's basically my line of thinking.

[Artorius]

Excellent post mokele,I prefer this person to the one previous.I followed each point with relish,i disagree with some but i think it prudent to only congratulate you on a well presented post.

Arty

[Mokele]

Thanks very much, both of you.

 

I guess not having a life can pay off after all...

 

Mokele

[Ophiolite]

Mokele, if I am reading you correctly (and I have only quickly scanned the recent posts) you are of the view no dinosaurs were warm blooded. If this is correct are you up for a debate in the New Year?

[Mokele]

Mokele, if I am reading you correctly (and I have only quickly scanned the recent posts) you are of the view no dinosaurs were warm blooded. If this is correct are you up for a debate in the New Year?

 

It's not correct, though it would make an interesting debate. I suspect they had a diverse range of metabolic rates, though I also suspect that few were quite as high as some suspect. The large ones are unlikely to have had very high metabolisms, due to the low surface area to mass ratio, but the small ones may have had higher matabolisms. How high is debatable, though; after all, while we know dromaeosaurs were fast, how do we know they weren't near-ecothermic sprinters as opposed to endothermic marathon runners? Or maybe something in between?

 

So, while my position isn't exactly as you thought, I'd still enjoy a good debate on the subject, if you would. Unless by sheer irony this is your position too. Even then, though, I could take the "all ectotherm" stance just for kicks and to play Ectotherm's advocate.

 

Mokele

[Ophiolite]

I don't have a firm view either way, though I have followed the developing ideas over the last decade or two with interest. I proposed the debate because I knew it would provide some focus for me to look more closely at the issues. Let's revisit this in the new year, when my schedule will be a little clearer to me (which will also give me some time to do some provisional 'swatting').

 

And let me add to the others' comments - good posts.