Extinction of Dinosaurs take X

[foodchain]

In many cases modern paradigms of biology seem to be just that. They seem to be as mutable as the subject itself, squirming and full of tenacity relativity. In the advent of more modern synthesis movement of hereditary material seems to follow strictly direct reproduction. Horizontal gene transfer is seemingly becoming more or more a larger factor in evolution then previously held by the field. As such the manner in which life reflects evolution I find may be more meshed then previously understood. For instance, the simple ability of viral variation can allow for large scale death. The reality or impact of this variant does not have to seemingly hold the same for all species at all time in regards to overall viral behavior. None the less taking into account the immune system viral variation certainly equals large scale impact biologically speaking.

 

Now giving certain realities of natural selection. Is it possible giving such realties today via antibiotics that a super bug has appeared in the past. A bug with such ability to register such a large scale extinction. I don’t mean directly that the bug was capable of killing every specie of dinosaur. Just enough to disturb evolution in a manner reflecting to such a scale. The reality of this is such a bug may have been highly successful at just picking part maybe a troph at high population density environments. Whatever fossils come to be found surely are used to probe at the realities of death for the animal, but its alos possible I think for the bug to be not visible in such a collection, or overall it would be a possibility still valid.

 

I think giving ecological realities that such a bug could have the ability to spread rapidly around the globe. This variable can be viewed from multiple biologic avenues. Such as bacteria that attacks eggs. I see this as a possibility because domains of life from prokaryotes to even eukaryotes seem to reflect a highly specialized evolutionary adaptation which I feel reflects in autotroph behavior and subsequent succession of life from a natural selection orientated stance. So overall multicultural species have evolved parallel to other strategies or forms of life in accordance with natural selection. The related impact this holds I do not feel is fully understood nor registered in the field itself. Microbial life from the later understands of gene transfer to virus behavior I think surely represents a higher order to evolution in regards to factual understanding of life.

 

Such as timeline speaking. When high speciation numbers are reached is there any change in behavior of microbial history?

 

What is the relationship between microbial phylogeny compared to animal phylogeny for instance?

 

I think these questions and the related subject at hand should receive heavy attention for the reality of how its already effected life to how it effected life in the past. As such could it have been possible for a microbial perturbation to life so extreme as to trigger mass extinction as found with the dinosaurs.

[CDarwin]

I'm interpreting that as: The dinosaurs were killed by a super-disease that left no trace in their fossils.

 

The question needs be: Is there any way to test this assertion?

[Edtharan]

The question needs be: Is there any way to test this assertion?

Diseases can leave traces in fossils. Have a look at the "Big Al" fossil. It shows that "Big Al" had a chronic infection in his foot.

 

Not all diseases will leave a trace, but it is possible.

 

Also, there were many species of Dinosaur, so this disease would have had to cross species boundaries. It would be a bit like a disease that today effected all Mammals (with none having any resistance - otherwise there would be survivors). Plus, there were many more species of Dinosaur than there are Mammals today, so this disease would have had to have been far worse than any plague known. So it is extremely unlikely that a disease wiped out the dinosaurs.

[foodchain]

Well the question could be viewed as a more or less question on the relationship and behavior of various microbial life. Such as does the virus somehow equate into autotroph behavior. I think an artful example would be energy always being pulled back down.

 

The other reality or basically a question be did endosymbiosis ever really stop? I mean it seems all life eventually returns back to that troph. So life evolving obviously parallel to microbes such as bacteria or the virus has evolved an immune system. With that reality dinosaurs and all life then had to rely purely on the immune system in order to survive such.

 

I don’t know exactly but I am sure the simple size of the dinosaurs became an acute reality, probably reflecting in say size of clutch or reproduction rates and survival rates. The actual phylogeny+physiology of dinosaurs though would have to be understood fully for realization of such, ecological niches accordingly also would be represented here. You have to remember that microbes due to mutation rates for one example can rapidly occupy a wide array of environments, including other organisms. They do this constantly, and I would have to say of course because of evolution such is why we exist.

 

The point I am trying to make, it egg laying by such species existed for some time. That is a rather large energy source I would say in constant contact with various microbes. I also imagine the amount of manure some dinosaurs generated was huge. Its hard to say the rates in which microbes would adapt to attack really, more so if it were just eggs of key species. If a large enough of a plague attacked really key species I could see it also as a means to allow for farther radiation. I think speciation rates of dinosaurs might allow data for such an idea, though of course I don’t know. Also other life at that point could also radiate, and giving natural selection local flora could have been heavily impacted along with more of a disturbance on dinosaurs overall. If it just hit the eggs and drastically killed off already slow reproduction rates again of key species in an ecology, and giving the ability of microbes to pass say genetic information, I think such is a possible reality of extinction when compared with other factors, such as over predation becoming a reality then allowing for more rapid radiation of other organisms.

 

Of course this is all speculation.

[Sayonara]

Also, there were many species of Dinosaur, so this disease would have had to cross species boundaries. It would be a bit like a disease that today effected all Mammals (with none having any resistance - otherwise there would be survivors).

Well, not necessarily. It might be that there is resistance there but not enough to leave surviving individuals within encounter range of each other, thereby disrupting breeding enough to crash populations, and subsequently crashing trophic networks.

 

Although that does seem somewhat unlikely on a global, pan-species scale.

[foodchain]

Well, not necessarily. It might be that there is resistance there but not enough to leave surviving individuals within encounter range of each other, thereby disrupting breeding enough to crash populations, and subsequently crashing trophic networks.

 

Although that does seem somewhat unlikely on a global, pan-species scale.

 

 

This does not automatically preclude any reality of a global plague. The exact environment would have to entail such a "unknown" virus or bacteria for instance to remove it from the idea.

 

I do like again the idea of speciation a reaction to viral life for instance but the idea of the immune system counters such to a large extent. Again realties such as gene transfer are hinting at a far more complex environment of interactions then previously held. Then again maybe this is why biting fingernails is a easy to find as a habit, and personally I don’t see how this could ever aid in keeping you healthy, biting finger nails that is.

[Sayonara]

It was not intended to preclude any reality of a global plague. Quite the opposite in fact; I was proposing a means of causing mass extinction without requiring complete mortality.

[CDarwin]

Diseases can leave traces in fossils. Have a look at the "Big Al" fossil. It shows that "Big Al" had a chronic infection in his foot.

 

Hence the "left no trace" qualification. There isn't any evidence of pandemic infection in the bones of most dinosaurs that died around the K-T boundary. I think the comet is still pretty much the best explanation.

 

Also, there were many species of Dinosaur, so this disease would have had to cross species boundaries. It would be a bit like a disease that today effected all Mammals (with none having any resistance - otherwise there would be survivors). Plus, there were many more species of Dinosaur than there are Mammals today, so this disease would have had to have been far worse than any plague known. So it is extremely unlikely that a disease wiped out the dinosaurs.

 

It could have just struck particular families of dinosaurs and thus compromised ecosystems. Say it killed enough of the Ceratopids to disrupt reproduction and collapse the population, and that was a big enough effect to collapse whole dinosaur food chains. Again, not horribly likely and there's no real way to test it, though.

[Edtharan]

This does not automatically preclude any reality of a global plague.

At the K-T boundary, the super continent (Pangea) had already broken up, so there would have been very little transfer between the new continents (Gondwana and Laurasia - and these were also breaking up around the K-T boundary too). This means that a plague that started in one location would not have been able to travel (easily) to another continent.

 

Unlike today, we have international travel that allows us to move quickly between all parts of the world. This is what has allowed the pandemics to occur. It is possible for diseases to spread over natural barriers (mountains, oceans, etc) like what is happening with migratory birds and H5N1 influenza.

 

So even if there did evolve a disease that effected enough individuals in an ecosystem to crash it, there were many different ecosystems and on several different continents. This makes ant global plague almost impossible.

 

Say it killed enough of the Ceratopids to disrupt reproduction and collapse the population, and that was a big enough effect to collapse whole dinosaur food chains. Again, not horribly likely and there's no real way to test it, though.

But, a disease that is fatal enough to wipe out entire species will have a negative feedback effect on it transfer (as the carrier species would be subject to it, or the species that it relies on would get wiped out).

 

Also, diseases are a "parasite" as they can only exist within their hosts. So any disease that wipes out it's host species would be on an evolutionary dead end. As the disease started wiping out it's hosts, it would have less and less chance to transfer it's self, whereas a disease that was less lethal would have more hosts to transfer to and so would out compete the more lethal strains.

 

Also, any individuals that had a resistance to a highly lethal strain would have a major advantage, so as the disease progressed through a population, and wiped out most of them, those that were left would be faced with lots of resources (less competition) and a resistance to the disease.

 

These survivors would encounter fewer animals that had the disease (due to the fact that there are less animals, any one the had the disease would be more likely to die before encountering another to transfer the disease), and so would transfer the disease less often. Coupled with an increase resistance, this means that a highly lethal disease would most likely make it's self extinct before it's host population (or the host population would be come resistant).

 

More likely though, the disease would evolve into a less virulent or less lethal strain.

[CDarwin]

At the K-T boundary, the super continent (Pangea) had already broken up, so there would have been very little transfer between the new continents (Gondwana and Laurasia - and these were also breaking up around the K-T boundary too). This means that a plague that started in one location would not have been able to travel (easily) to another continent.[/Quote]

 

Two superbugs? One that hitches a ride on a Pterodactyl?

 

But, a disease that is fatal enough to wipe out entire species will have a negative feedback effect on it transfer (as the carrier species would be subject to it, or the species that it relies on would get wiped out).

 

Also, diseases are a "parasite" as they can only exist within their hosts. So any disease that wipes out it's host species would be on an evolutionary dead end. As the disease started wiping out it's hosts, it would have less and less chance to transfer it's self, whereas a disease that was less lethal would have more hosts to transfer to and so would out compete the more lethal strains.

 

Also, any individuals that had a resistance to a highly lethal strain would have a major advantage, so as the disease progressed through a population, and wiped out most of them, those that were left would be faced with lots of resources (less competition) and a resistance to the disease.

 

More likely though, the disease would evolve into a less virulent or less lethal strain.

 

Tell all that to HIV. Obviously, a disease that kills every last member of species is pretty implausible, but once you got the this stage:

 

These survivors would encounter fewer animals that had the disease (due to the fact that there are less animals, any one the had the disease would be more likely to die before encountering another to transfer the disease), and so would transfer the disease less often.

 

Then the species is pretty much shot, since individuals aren't going be encountering potential mates, either.

[Mr Skeptic]

Also, diseases are a "parasite" as they can only exist within their hosts. So any disease that wipes out it's host species would be on an evolutionary dead end.

 

I believe the term for that is "Oops!"

 

As the disease started wiping out it's hosts, it would have less and less chance to transfer it's self, whereas a disease that was less lethal would have more hosts to transfer to and so would out compete the more lethal strains.

 

Ah, but that would require that the deadly strain didn't get to them first. If there were systems that didn't get infected with the deadly strain, then it wouldn't cause extinction whether or not there was a less deadly strain.

 

----

 

I think a perfect extinction germ would be one that causes permanent sterility. That is deadly for its host from an evolutionary standpoint, but not to the bacteria, which will have as long as it likes to spread.

[iNow]

I think a perfect extinction germ would be one that causes permanent sterility.

Like in Children of Men.

[Edtharan]

Tell all that to HIV.

If it wasn't for the fact that we are able to rapidly travel to all parts of the globe, HIV would not have been as serious as it is. It would have been confined to a small part of the world and probably evolved (along with the humans in that area) to less deadly to them.

 

Take for example diseases like Chicken Pox. To those of us that have been exposed to it (and our immune systems have acquired resistance) and the fact that we have evolved along side this disease for millennia, this disease is not too serious (it can be fatale in a few cases), however, when Europeans were colonising the world, they brought this disease to populations that had not been exposed to it and so were not evolved to handle it (and the diseases they have, we are not evolved to handle), and so it spread through their populations killing most of them.

 

Evolution towards non lethality is both in the host and the disease. However, it is also true that there are some disease that appear and are extremely lethal and the hosts and the disease don't have the time to adapt to each other.

 

There can also be other factors, like the disease being able to exist within several different hosts (a bit like what they think is occuring with Bird flu at the moment). As the disease starts to cross species boundaries, it has two (or more) hosts that it can exist in, so if it is deadly to one, it is not too big of a problem for it.

 

Even in this scenario, if the disease is going to spread in the second population, it still needs to evolve less lethality or it will still only be a local problem.

 

Ah, but that would require that the deadly strain didn't get to them first. If there were systems that didn't get infected with the deadly strain, then it wouldn't cause extinction whether or not there was a less deadly strain.

If a disease was virulent enough to kill its hosts quick enough so that they couldn't adapt, then it would also kill it's hosts fast enough to limit it's expansion. For this disease to also kill off the dinosaurs, it would have to cross species boundaries many, many times which requires long repeated exposures. These two situations are almost mutually exclusive.

 

Is it possible that it could occur? Yes. Is it even remotely likely? No.

 

I think a perfect extinction germ would be one that causes permanent sterility. That is deadly for its host from an evolutionary standpoint, but not to the bacteria, which will have as long as it likes to spread.

This would be one way that it could work. But it still has the problem of jumping species multiple times as well as crossing geographical barriers.

 

However, as there were no fast transportation systems (no jets, highways, etc), it would have taken generations for this kind of disease to spread across the world. So if it make them all sterile, how would have it been able to take generations to spread?

 

Two superbugs? One that hitches a ride on a Pterodactyl?

It would have to be more than 2 superbugs as Gondwana and Laurasia were also breaking up at the time the Dinosaurs went extinct. Not to mention all the small islands and such that existed.

 

For the superbug to hitch a ride on Pterodactyls, it would first have to cross the species barrier (remember that Pterodactyls are not dinosaurs) to them, not be lethal enough to kill them all (but then re-evolve that lethality later) or make them too ill to fly between continents, and finally re-cross the species barrier back to a different species of dinosaur.

 

And this has to not only occur ones, but many times across every continent and island. If this superbug didn't get to every single island, then there would ahve been an island (maybe like Madagascar), where they could have survived as that ecosystem would have not been decimated by the superbug and therefore would have remained intact.

 

Even with modern humans ability to travel anywhere in the world quickly, the chances that something like this occuring with us is astronomically small. Imagine this occuring without passenger jets or other modern transportation systems. Disease just is not capable of wiping out all of the Dinosaurs, even if it was bad enough to disrupt ecosystems, the world is just too remote for it to occur.

[foodchain]

Universal biochemistry(almost universal) for life currently on earth does not also mean the virus or microbe for instance as posed for an extinction mechanism needed to attack directly the individual organism as is. It could possibly have evolved to attack eggs. Also the reality to me is even without large scale transportation mechanisms known from various periods of time, such as birds today, or mass transport as pointed out. Such conditions overall do not rule out such as a possible mechanism. Also as principle giving natural selection I always tend to think about the "oddball" so to speak. Now a duckbill platypus might simply be an example of convergent evolution, but its future as in its bill is certainly a rarity. That along with natural selection does not seem to fit a mode of strict determinism so to speak.

 

Population genetics has many nifty equations trying to relate a genome to a specific phenotype or what not. The reality to me is you have your genome, phenotype and then for lack of better words life and related biological processes carrying out in natural selection. Taking into account simply mutation for another example and of course leading up to biodiversity I do not think its safe to simply assume.

 

So in reality maybe this bacteria could go into a state of cryptobiosis for example, or some extremophile type behavior. Maybe spores could play a role, there is many many routes I think to study such from. I mean if bacteria for instance can come to haunt the crust of the earth, I do not see how an immune system is a perfect defense, nor is it in reality. Then again what is perfect in evolution?

[Edtharan]

I have been thinking a bit more about this since my last post.

 

What if it was a retrovirus. If this virus, when inserting it's self into the genome of the host creature, made a change to the host that wasn't immediately lethal. What if the change produced a regressive "mutation" in the host, that is it wouldn't show up unless two "parents" have an offspring together.

 

I am thinking an effect a bit like sickle cell anaemia. If one parent has it, then it is either neutral or maybe even beneficial (it might protect against other diseases like SCA does). But if two parents have it, then it becomes a disease.

 

The result of this disease could be that it makes the offspring sterile. This of course would not be the primary effect of the disease.

 

So animals can become infected with the retro virus, pass it along and not get too sick. However, if a creature that was infected mates with another that wasn't infected, then they produce an offspring with the retrovirus caused mutation in one of their chromosomes.

 

As this progresses, the virus (due to the fact that it is not lethal) is able to spread widely and even cross species barriers (it would have the time), but as it develops, more and more animals will encounter another that has either been infected or carries the mutation. If these two mate, then they produce an offspring that is sterile.

 

This kind of sterility has been used by humans (we use radiation to cause the sterility) to control insect plagues. I don't know if a retrovirus could cause such a mutation, but it could easily devastate large populations if it could. Also, the fact that this sterility is a regressive rather than a dominant trait means that it lies dormant in the population until it reaches a critical threshold and then reproduction becomes very difficult and the population (and ecosystems) crash.

 

Of course, this is pure speculation in an attempt to think of a way that a disease could gain such a wide spread foothold that it could cause such a mass extinction event across multiple species and ecosystems (not to mention geographic locations too).

[foodchain]

I have been thinking a bit more about this since my last post.

 

What if it was a retrovirus. If this virus, when inserting it's self into the genome of the host creature, made a change to the host that wasn't immediately lethal. What if the change produced a regressive "mutation" in the host, that is it wouldn't show up unless two "parents" have an offspring together.

 

I am thinking an effect a bit like sickle cell anaemia. If one parent has it, then it is either neutral or maybe even beneficial (it might protect against other diseases like SCA does). But if two parents have it, then it becomes a disease.

 

The result of this disease could be that it makes the offspring sterile. This of course would not be the primary effect of the disease.

 

So animals can become infected with the retro virus, pass it along and not get too sick. However, if a creature that was infected mates with another that wasn't infected, then they produce an offspring with the retrovirus caused mutation in one of their chromosomes.

 

As this progresses, the virus (due to the fact that it is not lethal) is able to spread widely and even cross species barriers (it would have the time), but as it develops, more and more animals will encounter another that has either been infected or carries the mutation. If these two mate, then they produce an offspring that is sterile.

 

This kind of sterility has been used by humans (we use radiation to cause the sterility) to control insect plagues. I don't know if a retrovirus could cause such a mutation, but it could easily devastate large populations if it could. Also, the fact that this sterility is a regressive rather than a dominant trait means that it lies dormant in the population until it reaches a critical threshold and then reproduction becomes very difficult and the population (and ecosystems) crash.

 

Of course, this is pure speculation in an attempt to think of a way that a disease could gain such a wide spread foothold that it could cause such a mass extinction event across multiple species and ecosystems (not to mention geographic locations too).

 

 

Well if memory serves reptiles are not restricted as much as mammals happen to be in terms of body size and local environment. I do not know if this is what allowed the dinosaurs come to exist or not. It sort of makes sense in a timeline in regards to evolution. The point I will try to get at is dino physiology has to be inferred to a certain extent without the aid of direct studies. I do not think this gets rid of the paradigm on dino extinction, I just think such is a good playground really to bounce ideas around in. Giving natural selection a radically different world existed to a certain extent.

[CDarwin]

It would have to be more than 2 superbugs as Gondwana and Laurasia were also breaking up at the time the Dinosaurs went extinct. Not to mention all the small islands and such that existed.[/Quote]

 

As I recall, Laurasia stayed more-or-less intact until the Eocene.

 

For the superbug to hitch a ride on Pterodactyls, it would first have to cross the species barrier (remember that Pterodactyls are not dinosaurs) to them, not be lethal enough to kill them all (but then re-evolve that lethality later) or make them too ill to fly between continents, and finally re-cross the species barrier back to a different species of dinosaur.

 

That's quite a bit more than a species barrier. Aren't those two different sub-classes?

[Edtharan]

That's quite a bit more than a species barrier. Aren't those two different sub-classes?

I meant: from the first species of Dinosaur that give the disease to the Pterodactyl. I understand that a Pterodactyl is not a Dinosaur. Sorry my wording was not clear .

[foodchain]

I meant: from the first species of Dinosaur that give the disease to the Pterodactyl. I understand that a Pterodactyl is not a Dinosaur. Sorry my wording was not clear .

 

I would not feel to bad as numerous species on up exist, or really the count is so numerous one typically has to specialize or use books with pictures;) I mean how many people know what the common house cat evolved from.

[bombus]

sshurely everyone knows what happened? Intelligent, bipedal, technologically advanced dinosaurs ruined their ecosystem causing extinctions of many families. Climate chaos then lead to nuclear war which finished them all off (apart from the few that escaped in flying saucers).

 

All we gotta do is find the remains of dinosaur cities...

[Edtharan]

All we gotta do is find the remains of dinosaur cities...

The chances of finding something like that, even if it did exist, would be next to zero.

 

Stone buildings only 1,000 years old are still hard to find (sometimes all they are are a discolouration of the dirt and rocks). Imagine finding something that was 65,000 times (or more) older.

 

However, if we did find even a small "building" it would be one of the most amazing pieces of archaeology to ever be discovered. It would rank up there with finding intelligent life on another world.

[lucaspa]

Such as timeline speaking. When high speciation numbers are reached is there any change in behavior of microbial history?

 

What is the relationship between microbial phylogeny compared to animal phylogeny for instance?

 

I think these questions and the related subject at hand should receive heavy attention for the reality of how its already effected life to how it effected life in the past. As such could it have been possible for a microbial perturbation to life so extreme as to trigger mass extinction as found with the dinosaurs.

 

Robert Bakker proposed that dino numbers and species diversity were decreasing long before the meteor impact at the KT boundary. His idea was that land bridges and plate tectonics were allowing the migration of species of dinos on one continent to others. So there was now an intermingling of similar species that before had been isolated.

 

He proposed that this intermingling allowed diseases that were well-adapted to their host populations to break into virgin populations. It is well-known that both the microbe and the host populations evolve rapidly. A microbe breaking into a virgin population (such as jumping species) causes a much more severe reaction from the host -- a reaction that often kills the host. This creates a crisis for the microbe: if the host dies, all the microbes (virus or bacteria) die also. Unless, of course, some of them have managed to infect a new host.

 

Over the course of generations, both the host and the microbe evolve to reduce virulence (the severity of the disease). The microbe then becomes a "childhood" disease. When measles, mumps, whooping cough, etc. first were introduced into European populations in 100 - 400 AD, they caused widespread epidemics and high mortality. Altho they all were referred to as "plagues", don't leap to the conclusion that they were bubonic plague. By 1500 AD all these had adapted and were childhood diseases. Then when the Europeans invaded the Americas, these relatively mild diseases to the Europeans became deadly "plagues" to the American Indians, causing widespread mortality and the extinction of scores of tribes. See the book Plagues and Peoples by MacNeil.

 

Bakker proposed that something similar happened between 70 and 65 Mya. The order Dinosauria was already in decline and heading for extinction when the meteor finished off the last of them. Detailed population studies in the Hell Creek formation are consistent with the hypothesis. But there is no way to tell how widespread or effective this was. Today we see diseases jumping from species to a new species and causing widespread population decline, but I don't know of any observed extinction due to this.

 

Well if memory serves reptiles are not restricted as much as mammals happen to be in terms of body size and local environment. I do not know if this is what allowed the dinosaurs come to exist or not.

 

How are mammals "restricted in terms of local environment"? Mammals are found in all sorts of climates. It is the sauropsids that are more limited: they cannot exist in frigid environments like the polar bear and caribou do.

 

I have seen that dinos gained the upper hand over early mammals because of increased mobility. The early dinos were bipedal and thus able to move faster and quicker than the early mammals. Try the "Walking with Dinosaurs" series. The segment of life before the dinos goes into the advantages of bipedality.

[bombus]

The chances of finding something like that, even if it did exist, would be next to zero.

 

Stone buildings only 1,000 years old are still hard to find (sometimes all they are are a discolouration of the dirt and rocks). Imagine finding something that was 65,000 times (or more) older.

 

However, if we did find even a small "building" it would be one of the most amazing pieces of archaeology to ever be discovered. It would rank up there with finding intelligent life on another world.

 

Indeed, 'tis so. It would make the human race shudder and think again methinks - perhaps even more than finding intelligent life elsewhere...

 

I still go for Self Organized Criticality as the most likely cause, with the meteorite being a final nail in the coffin. I think biology/ecology/evolution follow mathematical principles and patterns. Everything else seems to so why not. Extinctions follow Power Law principles - lots of small extinctions with fewer large ones. The Earth is all one huge dynamic system, perhaps with plate tectonics being part of it.

[foodchain]

How are mammals "restricted in terms of local environment"? Mammals are found in all sorts of climates. It is the sauropsids that are more limited: they cannot exist in frigid environments like the polar bear and caribou do.

 

I have seen that dinos gained the upper hand over early mammals because of increased mobility. The early dinos were bipedal and thus able to move faster and quicker than the early mammals. Try the "Walking with Dinosaurs" series. The segment of life before the dinos goes into the advantages of bipedality.

 

I don’t know if this applies to dinosaurs directly but I heard it applied to reptiles. IN that reptiles and mammals, say both on a small island for instance. The size of the island would not denote the reptiles becoming small over time, in fact they would most likely become larger. Mammals on the other hand don’t do this, in that the size of the ecology does not state that if it is small so will the reptiles. I think its just a hypothesis but if I remember correctly it came about from trying to find out more about human evolution.

[lucaspa]

I still go for Self Organized Criticality as the most likely cause, with the meteorite being a final nail in the coffin.

 

Please define this and give us some sources, as well as a description of how this causes extinction, especially of widely distributed species or groups of species.

 

I think biology/ecology/evolution follow mathematical principles and patterns.

 

They do. Population genetics is the mathematics of natural selection. However, biology/ecology/evolution also incorporate contingency. Because events outside biology can profoundly influence biology (such as solar input or plate tectonics), biology/evolution can never be as deterministic as classical physics. Also, since individuals vary, this also forbids biology/evolution from being strictly deterministic, but instead being probabilistic.

 

The chances of finding something like that, even if it did exist, would be next to zero.

 

Stone buildings only 1,000 years old are still hard to find (sometimes all they are are a discolouration of the dirt and rocks). Imagine finding something that was 65,000 times (or more) older.

 

You wouln't be able to find buildings for the reasons you noted. However, gold, silver, and gem jewelry would be a better bet. Since all are stable, if we could find say, a gold ring or a cut emerald, that would be signs of intelligence. There was actually a sci-fi short story the author used a gold ring was found around the finger bones of a dino. The author also used something like the Laetoli tracks, only incorporating the impressions of a wheeled cart or wagon.

 

I don’t know if this applies to dinosaurs directly but I heard it applied to reptiles. IN that reptiles and mammals, say both on a small island for instance. The size of the island would not denote the reptiles becoming small over time, in fact they would most likely become larger. Mammals on the other hand don’t do this, in that the size of the ecology does not state that if it is small so will the reptiles. I think its just a hypothesis but if I remember correctly it came about from trying to find out more about human evolution.

 

This comes from the studies on H. floriensis, the "hobbit" fossils on the island in Indonesia. The idea is that, on small islands with a restricted food supply, large mammals evolve to be smaller. On this particular island, H. floriensis would be smaller H. erectus and there were also "dwarf mammoth" bones on the island. Mammoths isolated on the island also evolved to be smaller, so that they would use less food.

 

Sauropsids, being cold blooded, tend to need less food than warm-blooded mammals. However, there is considerable evidence that dinos were at least partially warm-blooded. The only descendents of dinos around -- birds -- are fully warm blooded. So we can infer that what happens to large mammals on small islands happens to large dinos. However, notice that small mammals don't get smaller. The mice and rats on the island stayed the same size.

 

None of this restricts the habitats that mammals can occupy. After all, the hominids and mammoths adapted to the small island, so they can occupy that habitat.