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Why did birds, of all the dinosaurs, survive the KT event?

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shock quartz around the entire planet? i'm not exactly sure what you mean, how does the current theory explain how the quartz got shocked?

 

what i find strange about the theory that an asteroid caused all this raucus is that the crater looks round on the earth tody, doesn't it? but the earth at this period in history was much different. even in that specific part

 

http://www.scotese.com/images/066.jpg

 

maybe the ability to climb trees or fly or swim was crucial to survival and all land animals that couldn't do this drowned. or couldn't eat the food in the trees that poked out of the water or ice and their usual food that grew closer to the ground was covered. but still you would think that if food was the problem the carnivores may have have lasted the longest apart maybe for small animals because they would still have food until all the other creatures died and even then they could start eating themselves.

 

what's the leading suspected cause of death of the dinosaurs we've found so far?

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I find mind boggling that you still do not understand that big bodies have smaller surface in relation to their volume and therefore conserve temperature better.

 

He understands that just fine. I'll admit he is not making the best possible case but the principles he is arguing from are sound.

 

Get away from the habit of thinking about individual survival and think about species dynamics. Individuals do not evolve or go extinct - species do.

 

The reasons the species with smaller size survived are:

 

1) The lower resource cost per unit biomass of population could be more commonly supported by whatever food item biomass remained after the catastrophe,

 

2) The adaptive features of feathers, fur etc have vastly more pronounced effects on proportionate rate of heat loss for smaller organisms than they would for larger organisms, reducing the mortality rate across the population much more sharply,

 

3) Smaller species frequently have shorter generational cycles than large species, and more frequent and productive breeding cycles. This would have amplified selective effects, shored up food item biomass (we of course assume some of the smaller species were carnivorous or carrion eaters), and of course increased the probability of each generation being viable in terms of further breeding.

 

Therefore two significant pressures that were too much in combination for the larger species could have been much less of an issue for the smaller species, in fact they could strongly select towards rapid adaptation to the conditions.

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He understands that just fine.

 

Why don’t you leave him to defend his own position, Sayonara ?

 

And no, so far he failed to understand it or for some reason he does not want to admit his error.

 

I think that there is no problem having the humility to admit errors. Even the most brilliant minds commit errors.

 

Get away from the habit of thinking about individual survival and think about species dynamics.

 

What makes you assume that I miss species dynamics ?

 

Individuals do not evolve or go extinct - species do.

 

But species are made up of individuals. Each one of them influences the perpetuation of its species. If an individual has more adaptive genes than the rest, he probably will leave more viable descendants and then influence in some degree the genetic profile of his population.

 

Some times just few individuals ( pioneers ) can even start a new species through accidental geographical separation after hundreds or thousands generations.

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But species are made up of individuals. Each one of them influences the perpetuation of its species. If an individual has more adaptive genes than the rest, he probably will leave more viable descendants and then influence in some degree the genetic profile of his population.

 

Some times just few individuals ( pioneers ) can even start a new species through accidental geographical separation after hundreds or thousands generations.

 

granted species are made of individuals and one individual will influence the genetic profile of his population, but this would take a whole lot of time and requires other factors.

 

human beings are born with genetic mutations all the time but without other forces at play (reasons for them to die or not die due to these mutations) this has not and will not change the species as a whole.

 

I don't know if i would say that individual pioneers really 'start' a new species. granted if they get geographically separated a new specie could emerge but how can you say who started it? maybe no mutations took place from the pioneers and only further generations later. would you still say the pioneers started it in that case? what if the natural conditions slowly changed over time and the species adapted? who started that one? is it really different if your environment changes around you or if you move to a different environment? what if it was both? before technology changing environment was probably pretty much as gradual as if the environment slowly changed around you. it may take generations to travel somewhere where the environment is significantly different.

 

it's like the chicken and the egg... literally. it would be a slow process requiring a community and the resulting specie would be a mix of the whole gene pool intermixing over generations. not really individuals one individual can't change specie so then necessarily it needs to be specie dynamics.

 

maybe this is what you meant, and if so then i think you were both right.

 

back to the dinosaurs

 

how fast did it take for these species to go extinct?

 

it wasn't just small creatures that survived it wasn't just birds that survived, it wasn't just creatures with fur, i think there must be something else we are missing.

 

a quick reproductive cycle is a good one but going on size is not really conclusive parrots live as long as we do and turtles live a really long time and they're old. maybe i'm wrong but i don't think we could really know at what rate the species that died reproduced more frequently than the others. crocodiles live for like 40-50 years. but really what matters is how often they "give birth" and from what i can tell most animals do that once a year birds or otherwise, insects tend to do it. crocodiles and turtes don't really seem well suited to withstand the cold, and apparently creatures everywhere went extinct, if animals developed ways or resisting cold by evolution, they would have needed to live where it gets cold. birds migrate though, so maybe that has something to do with it, maybe the animals that migrate were slightly more adapted to cold and so they managed to survive. but crocodiles don't migrate and don't seem well adapted for cold either.

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Why don’t you leave him to defend his own position, Sayonara ?

Why should I? Why should I not also adopt the same position (so to speak)?

 

Lucaspa does not have any sole claim to explaining the answer to the question in the OP, and you don't get to choose who will respond to any given post.

 

And no, so far he failed to understand it or for some reason he does not want to admit his error.

The fact that you missed the reasoning or failed to understand it does not mean that it is invalid.

 

Lucaspa is making a distinction between the relative rates of energy loss in small and large species, and the absolute energy losses in each case. Understanding why these need to be considered differently is vital to this discussion. SkepticLance is ignoring the differentiation because he wants to talk about something else; don't follow him down that path because it leads to the dark side.

 

The bit you responded to with incredulity was "But the small birds of the savannah -- with their insulation and smaller body area to lose heat -- might live thru the blizzard.

 

The confusion arises here if one assumes that we are still talking about heat loss in relative terms. But at this point, the only thing we are interested in is heat loss in the absolute sense; that is, the total heat loss per individual per unit of food biomass available.

 

Large animals might lose heat at a lower rate relative to smaller animals and birds, you see, but they lose many times more heat energy per unit time. And that must be constantly replaced in a generationally viable number of the population in order for species to at least go on existing.

 

Considering the scenario -- that of a biosphere laid waste and a climate out of control -- we might reasonably assume that this survival cost is more easily met by the populations with the lesser requirements. And we would be right, because that is how it works.

 

What makes you assume that I miss species dynamics ?

I didn't say that you did forget about them. But you don't seem to be applying population-level thinking. If you were, your last post would have been agreeing with mine. It's not really a matter of opinion, after all.

 

But species are made up of individuals. Each one of them influences the perpetuation of its species. If an individual has more adaptive genes than the rest, he probably will leave more viable descendants and then influence in some degree the genetic profile of his population.

The difference between considering the mortality probability of an individual and the mortality rate of a species is not a simple matter of scaling up. A consequence of this is that the consideration of extinction likelihood falls apart if you are trying to explain it in terms of simple adaptive traits that are not uniformly distributed.

 

In a similar fashion, considering the process of selection in terms of a hypothetical "golden individual" is meaningless if the problem being examined is one that acts across not just a population, but all populations of that species.

 

Some times just few individuals ( pioneers ) can even start a new species through accidental geographical separation after hundreds or thousands generations.

I take it you meant a new population, rather than a new species.

 

This is actually very rare in higher animals, because they almost invariably have a less tolerant generational viability threshold than things like moss and asexual organisms.

 

Incidentally, that is not the correct use of "pioneer". Unless you actually do mean something along the lines of "plants that colonise barren environments", in which case I don't see how it is applicable to our birds and dinosaurs.

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I doubt that the essential difference, permitting birds and mammals to survive, was as simple as size. What we often forget is that there were a lot of small dinosaurs. It may be that there were a lot more species of small dinosaurs than big. Many were chicken size or smaller. New species appear to paleontologists searching for fossils every year. All of the arguments about the advantages of small size apply equally to small dinosaurs - yet they all died out.

 

It cannot be warm vs cold blood since lots of fully cold blooded reptiles survived. It cannot be insulation, since lots of dinosaurs had feathers. It cannot be ability to swim or fly, since lots of dinosaurs could do one or the other.

 

For all we know, it could be purest accident that led to enough birds, mammals, lizards, crocodiles etc surviving long enough to breed, while dinaosaurs did not.

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No, you are right: size is not the end-all factor in deciding survival during events such as the KT event.

 

But the evidence shows it is a significant factor in determining how likely species are to be driven extinct by that particular combination of selective pressures.

 

I sincerely and seriously doubt that with such strong pressures in effect that there were many, if any, accidental survivals. Biology is just not that vague.

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Hannibal used elephants to fight romans. They crossed the cold Andes mountains and survived.

I hear the hardest part was loading all of the elephants in boats and sending them to South America. A mite inefficient, but a great display of ingenuity.

 

 

 

Sorry, I couldn't resist.

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Since the elephants came up, is there any reliable historical source on how many didn't make it to the battle? Or, for that matter, what measures were taken to assist them in retaining heat, or how they were supported in terms of food?

 

Without those bits of information the reference is of questionable helpfulness.

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Hannibal used elephants to fight romans. They crossed the cold Andes mountains and survived.

 

Oops ... sorry the typo.

 

I actually meant to say:

 

"Hannibal used elephants to fight romans. They crossed the cold Alpes mountains and survived."

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I take it you meant a new population, rather than a new species.

 

This is actually very rare in higher animals, because they almost invariably have a less tolerant generational viability threshold than things like moss and asexual organisms.

 

 

I would have to disagree with this statement. change of environment is a large factor of why all creatures evolve or how they evolve. there's environment and other animals changing like an arms race. humans even evolved because of environment. but probably not from moving very quickly to a completely new environment, but moving to one that is sufficiently the same so that they don't die out in the first couple of generations and yet is different enough to value different genetic traits.

 

 

It cannot be warm vs cold blood since lots of fully cold blooded reptiles survived. It cannot be insulation, since lots of dinosaurs had feathers. It cannot be ability to swim or fly, since lots of dinosaurs could do one or the other.

 

I agree with you, but could it be possible if for example, just for the sake of argument, that the planet was flooded, birds could fly to higher ground some creatures could climb to safer ground and those that could swim could swim.

 

there may be one scenario that is ideal for many very different traits that can all compensate in their own way. that's why i think it would be helpful to know all the traits of the creatures that survived in their KT period state.

 

if there were many volcanoes in this period then maybe also swimming animals could survive even being cold blooded by finding refuge in waters warmed by volcanic activity, and birds fly to volcanic zones while being able to stay above the hot lava.

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I would have to disagree with this statement. change of environment is a large factor of why all creatures evolve or how they evolve. there's environment and other animals changing like an arms race. humans even evolved because of environment. but probably not from moving very quickly to a completely new environment, but moving to one that is sufficiently the same so that they don't die out in the first couple of generations and yet is different enough to value different genetic traits.

 

You say you disagree with my statement, then go on to argue something completely unrelated.

 

I was replying to blue_cristal's comment about primary colonisation by individuals, which is not in the slightest bit the same thing as migration.

 

If he is actually talking about migration (he didn't say, despite having responded to this thread since I questioned that point), then he needs to provide some means of showing how migratory relief is applicable in the context of the global catastrophe that this thread relates to.

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No, you are right: size is not the end-all factor in deciding survival during events such as the KT event.

 

But the evidence shows it is a significant factor in determining how likely species are to be driven extinct by that particular combination of selective pressures.

 

I sincerely and seriously doubt that with such strong pressures in effect that there were many, if any, accidental survivals. Biology is just not that vague.

 

 

How should I say this, its not that biology is vague its just natural selection. A specie, population of such, individuals in it, from the molecular to physiological level have a biology. This biology and there existence is tied to the ecology, or simply being able to survive in a giving environment. This environment is not the product of one aspect alone, such as being able to eat, which that in itself is most likely a composite of behaviors, etc... Now if you have an event which basically changes the environment of the earth in major, well this is going to resonate in life. The reasons birds made it is probably not just a few issues alone, I mean does coevolution ever cease to exist? and to be honest I don’t know why its actually separated from evolution save for the fact it might make it easier on a human observer.

 

Obviously some life managed to adapt and survive, a lot of life did not though, and to be honest you would also have to look at it from that scale too. Again, its probably not just a simple reason as to the why. I mean a majority of life that has existed is now extinct. How could so much life simply not make it? Even today though we still have a massive amount of biodiversity though.

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I'm confused. Are you agreeing or disagreeing with my analysis?

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The reason I suggested accident might be a factor was not really as a serious suggestion - just pointing out that we do not know, and do not have the data that might permit us to know. We simply do not have any idea why the dinosaurs died out while leaving so many other animal groups to survive, and later evolve by adaptive radiation into so many successful species. Though the chance factor is unlikely, with our level of ignorance, why should we reject it?

 

Another possible, but unlikely factor might be geography. Perhaps a small part of the world managed to get 'hit' a lot less than the rest by the after effects of the asteroid impact, and that part was made up only of islands that had life, but no dinosaurs. Hey, it is unlikely, but all we got is wild speculation.

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The reason I suggested accident might be a factor was not really as a serious suggestion - just pointing out that we do not know, and do not have the data that might permit us to know. We simply do not have any idea why the dinosaurs died out while leaving so many other animal groups to survive, and later evolve by adaptive radiation into so many successful species. Though the chance factor is unlikely, with our level of ignorance, why should we reject it?

 

Another possible, but unlikely factor might be geography. Perhaps a small part of the world managed to get 'hit' a lot less than the rest by the after effects of the asteroid impact, and that part was made up only of islands that had life, but no dinosaurs. Hey, it is unlikely, but all we got is wild speculation.

 

I don’t imagine the task impossible or that no explanation or theory on such exists, its just I think the direction of this thread started to go in the form of a constant for any form of life or specie to make it in regards to evolution, and as far as I know that’s not exactly how natural selection works. Typically the reasons may be similar, such as being able to successfully eat and reproduce, but the means of such I seriously doubt to be twins or exact copies, say crabs to fish, to reptiles to birds.

 

For instance, crocodiles. I would think the means of how that species managed to continue on through time is not the ways in which wasps have managed. It sounds simple to me but I think its one of those simple points that gets lost.

 

I mean can you factor in previous biomes, various ancestors of birds, types that have gone extinct, like the dodo, what doe the fossil record say about density of organic material at any giving time, etc...

 

I have personally never put a great deal of time into understanding why birds in specific managed to make it, so overall as to be specific I am not a great deal of help, I just did not want the question of this thread to go in some direction probably ill to the pursuit of any actually answers. I mean the same question could be asked of human cultures, why do some not make it and what causes change, I don’t know of some air of absolute understanding on that one exists currently either, but it does not prevent it from happening or humans from noticing or for that matter going to route of the dodo, today most likely at our own hands, but hey, its just biology.

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The reason I suggested accident might be a factor was not really as a serious suggestion - just pointing out that we do not know, and do not have the data that might permit us to know. We simply do not have any idea why the dinosaurs died out while leaving so many other animal groups to survive, and later evolve by adaptive radiation into so many successful species. Though the chance factor is unlikely, with our level of ignorance, why should we reject it?

I realise you didn't mean accident in the literal sense... let me put it another way: an event such as the KT catastrophe would put such mind-bogglingly massive stresses on the biosphere as to make even the minor predicted effects of selection and so forth pretty much a certainty.

 

Of course we can't 'know' the true fate of a species in every single instance, but in a scenario like this we can be confident that the models we have for understanding what is happening within the system are going to hold up well.

 

Another consideration is that what you might call "the sheerest accident" might go by another name in ecologist or population biologist circles... in fact, if it can cause an extinction, then it almost certainly will do.

 

Another possible, but unlikely factor might be geography. Perhaps a small part of the world managed to get 'hit' a lot less than the rest by the after effects of the asteroid impact, and that part was made up only of islands that had life, but no dinosaurs.

This is more likely than possible. The fact that so many species did survive indicates there must have been some terrestrial refuges, or some species which were simply not fatally affected by the changes to the environment, or more likely a combination of the two factors.

 

Hey, it is unlikely, but all we got is wild speculation.

That is not really true though, is it? Speculation would be "the birds survived because [insert something that has no biological basis]".

 

What we are doing is applying models of interactions to the problem, which are known to hold true for terran ecology. The reliability comes largely from the economics that underlies the thinking.

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But well deserved ;) The review has taken many things out of context and in many cases she just seems to have completely misunderstood what is actually being said, to the point of thinking M. Boulter is saying the opposite of what he is actually saying.

 

Please provide examples.

 

Well she is an Associate Professor, which isn't a real professor at all. M. Boulter has been the Secretary of the International Organisation of Paleobiology for over twenty years.

 

ROFL! Bombus, please don't display your ignorance quite so openly. An Associate Professor is a "real" professor. The ranks go: Assistant Professor, Associate Professor, Professor. ALL are "professors". In the USA Assistant Professor is a rank before you have tenure. When you are promoted to tenure you get the rank of Associate Professor. When you have served on an NIH Study Section, an editorial board of a journal, and a few other things, you are promoted to Professor. The chairman of my department is ranked Associate Professor!

 

He is also the Chair the UK Governments Biodiversity Steering group.

 

Now you are just trying to trot out the Argument from Authority.

 

Having met him on numerous occasions, I know him to be a modest, honest and very (very!) clever scientist, not the unscholarly, boastful, anti US data-thief Ms. Walker seems to portray. I'm sure if she met him she'd feel quite ashamed!

 

She isn't going on meeting him personally, but what he wrote in the book! The issue is still whether the book is as Dr. Walker portrayed it (and yes, you should use her professional title). So far, you haven't given us any evidence to the contrary.

 

Hannibal used elephants to fight romans. They crossed the cold Andes mountains and survived.

 

Actually, it was the Alps and all but 2 died. Those died shortly afterward in the swamps of the Po River. But here the elephants went thru quickly and the Carthaginians carried some food for them! And wrapped them in blankets and built fires for them. Is that going to happen in the blizzards of the nuclear winter following the meteor impact?

 

I find mind boggling that you still do not understand that big bodies have smaller surface in relation to their volume and therefore conserve temperature better.

 

I understand that quite well. I'm saying that there are other factors at work than just that one. You keep pointing to animals ADAPTED for living in the cold. In that case, size itself does not work, does it? You also need fur, fat, and behavioral adaptations. The dinos had none of those. For animals adapted to warmer climates and then thrust into a snowstorm/winter, the amount of surface area to lose heat to the wind does matter.

 

Small birds and small mammalians survived simply because they could protect themselves against cold by hiding inside burrows and require far less food to survive. If they had no feathers or fur ( plus burrows ) to compensate for small body size they would die first.

 

How many birds do you know that burrow? So that is wrong. Notice that you are repeating my arguments about requiring far less food than the larger dinos. Also notice that I am saying that they had the feathers and fur for insulation. But so did some of the larger dinos.

 

Oh, that makes sense. What are the common attributes of the creatures that ended up dying because of KT? Is there some sort of website you know of that shows images of most creatures that died and most that survived?

 

What materials were found in the layer of earth that makes KT visible?

 

what was the earth shaped like in that period?

 

I guess it's probably impossible or very difficult to accurately know what the climate was in all areas of the earth in those days since the climate is not strictly influenced by latitude, but has anyone ever constructed a climate model for that period?

 

1. One of the pieces of data that fuels the controversy over the KT impact is that there does not seem to be any commonalities of the animal species that survived vs those that went extinct. This is what Bakker bases much of his argument on.

 

2. The KT layer is very visible where it can be seen. It has high levels of iridium wherever it is found on the earth and many areas have shocked quartz crystals.

 

3. Many of the continents were coming together -- which is one reason Bakker makes his argument of new diseases killing off the dinos.

 

4. I don't know of a climate map, but I haven't looked. Have you?

 

Since the elephants came up, is there any reliable historical source on how many didn't make it to the battle? Or, for that matter, what measures were taken to assist them in retaining heat, or how they were supported in terms of food?

 

Without those bits of information the reference is of questionable helpfulness.

 

Yes, that information is available. I was going by memory from 3 books about Hannibal I have read, including Harold Lamb's excellent history. It looks like my memory betrayed me to some extent. Hannibal started with 40 elephants and 4 survived. They are only exposed to snow for about 5 days.

http://www.answerbag.com/q_view/45492

 

Of his 40,000 men, 10,000 died of cold and exposure. Hmm. The smaller species did better. :) Yeah, yeah, I know, the humans may have had more clothes. But the humans were also wrapping the elephants in blankets, too.

 

I doubt that the essential difference, permitting birds and mammals to survive, was as simple as size. What we often forget is that there were a lot of small dinosaurs. It may be that there were a lot more species of small dinosaurs than big. Many were chicken size or smaller. New species appear to paleontologists searching for fossils every year. All of the arguments about the advantages of small size apply equally to small dinosaurs - yet they all died out.

 

The smallest dinos known were chicken sized, but they were the ancestors of birds and were present 115 Mya. By the end of the Cretaceous there were true birds. So we are talking the size difference between shrews, chickadees, and chickens. Still a big size difference there.

 

It cannot be warm vs cold blood since lots of fully cold blooded reptiles survived. It cannot be insulation, since lots of dinosaurs had feathers. It cannot be ability to swim or fly, since lots of dinosaurs could do one or the other.

 

This is Bakker's argument. However, we would have to look carefully at WHICH cold-blooded reptiles and amphibians survived. There may be other behavioral considerations here. For instance, crocodile species only have to feed once a year. Some frog species can stand being completely frozen. That may be the reason they survived. As I noted, 3 out of 4 orders of birds also went extinct. So did many families of mammals. So it is not as if ALL birds and mammals survived.

 

It may have been that all dinos were simply larger and couldn't get enough food to keep them going when the ecosystem collapsed.

 

The question of feathered dinos would be: how many of the late Cretaceous dinos were feathered? We are getting lots of evidence from early in the Cretaceous, but not from the late Cretaceous.

http://www.nature.com/nature/journal/v400/n6739/full/400058a0.html

 

The ones I find are pretty large -- 2-3 meters long: http://www.dinosaurcollector.150m.com/featheredDinosaurs2.html

 

For all we know, it could be purest accident that led to enough birds, mammals, lizards, crocodiles etc surviving long enough to breed, while dinaosaurs did not.

 

SkepticLance, let's remember that we are dealing with species within the Classes of Reptilia, Mammalia, Aves, and Amphibia.

 

I agree with Sayonara that, generally, we are not dealing with "accident". However, for a few species, your argument may hold. A few species may have been lucky enough to be in an isolated valley with hot springs that kept the temps up enough for the amphibian and reptile species there to survive.

 

I don’t imagine the task impossible or that no explanation or theory on such exists, its just I think the direction of this thread started to go in the form of a constant for any form of life or specie to make it in regards to evolution, and as far as I know that’s not exactly how natural selection works. Typically the reasons may be similar, such as being able to successfully eat and reproduce, but the means of such I seriously doubt to be twins or exact copies, say crabs to fish, to reptiles to birds.

 

For instance, crocodiles. I would think the means of how that species managed to continue on through time is not the ways in which wasps have managed. It sounds simple to me but I think its one of those simple points that gets lost.

 

Originally we were just talking birds vs dinos. And I still want to remind you that 3 out of 4 orders of birds didn't make it! I think perhaps this thread has gone off is that we are working with the fallacy that ALL birds survived the KT extinction. That isn't true. Only a very few species survived!

 

http://www.tulane.edu/~bfleury/birds/birdlectures/originflight.rtf

"Most Cretaceous birds disappeared at the end of the Cretaceous, along with the dinosaurs End of the Cretaceous, the world was full of birds, coexisting with an incredible diversity of dinosaurs, many bird-like theropods like Caudipteryx Very poor understanding of the winners and losers among the groups of birds alive at the end of the Cretaceous Of the few that we know about, most joined their ancestors in extinction Hesperornithoformes, Ichthyornithiformes, Enantiornithes, all vanished without a trace Only the loons and some primitive shorebirds crossed the K/T boundary A stunning discovery from Antarctica adds the Anatidae to the growing list of survivors

Vegavis iaai is a distant ancestor of the ducks, geese, and swans Lived 70 mya, alongside T. rex Few species of Neornithes survived the great devastation at the end of the Mesozoic Explosive adaptive radiation (about 10 million years) early in the Tertiary that produced the modern orders of birds"

 

I would agree that crocodiles probably made it thru by 1) living in water which buffered the nuclear winter temps and 2) only having to eat once, or twice, or thrice a year. Wasps would be different. I would speculate that, living in hives, they could make the inside warmer by 1) beating their wings and 2) huddling together. Pretty much how honeybees get thru the winter now.

 

types that have gone extinct, like the dodo, what doe the fossil record say about density of organic material at any giving time, etc...

 

Foodchain, you are aware that dodos went extinct in historical times from human hunting, right? They have nothing to do with the KT extinction. What you would want to do is look at the species of birds that were alive in the late Cretaceous and compare the species of the enantiornithines, the hesperornithoformes, and the icthyornithoformes (the toothed seabirds) -- all of whom went extict at the KT boundary and the neornithines which did not.

 

http://www.google.com/search?q=enantiornithines&rls=com.microsoft:en-us&ie=UTF-8&oe=UTF-8&startIndex=&startPage=1

http://www.ucmp.berkeley.edu/diapsids/birds/hesper.html

http://www.bowdoin.edu/~dbensen/Spec/Icthyorniformes.html

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You say you disagree with my statement, then go on to argue something completely unrelated.

 

I was replying to blue_cristal's comment about primary colonisation by individuals, which is not in the slightest bit the same thing as migration.

 

If he is actually talking about migration (he didn't say, despite having responded to this thread since I questioned that point), then he needs to provide some means of showing how migratory relief is applicable in the context of the global catastrophe that this thread relates to.

 

Blue cristal--> Some times just few individuals ( pioneers ) can even start a new species through accidental geographical separation after hundreds or thousands generations.

 

Sayonara--> I take it you meant a new population, rather than a new species.

 

This is actually very rare in higher animals, because they almost invariably have a less tolerant generational viability threshold than things like moss and asexual organisms.

 

 

well then my bad i guess. i saw this on your post and i thought you were saying that it is rare for higher animals to evolve because of a change in their geographical location. And so i posted that i thought that this and an arms race between species are the only factors i can think of that cause the evolution of higher animals. If my post seemed out of context then either i misunderstood your post or I wrote mine badly or something.

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well then my bad i guess. i saw this on your post and i thought you were saying that it is rare for higher animals to evolve because of a change in their geographical location. And so i posted that i thought that this and an arms race between species are the only factors i can think of that cause the evolution of higher animals. If my post seemed out of context then either i misunderstood your post or I wrote mine badly or something.

Ah right, I did wonder what you were talking about!

 

No, obviously I was not saying it was rare for higher animals to evolve. I was saying it was rare among the higher animals for a few individuals to spontaneously generate a stable population in a new environment (in the way that pioneer plant species do, at least).

 

 

How many birds do you know that burrow? So that is wrong.

Sorry to undermine the argument, but I don't think this question is a terribly good rebuttal.

 

Firstly, a bird does not have to build a burrow to be able to shelter in it. This can be observed in action with modern species, my favourite of which is the Burrowing Owl: http://en.wikipedia.org/wiki/Burrowing_Owl

Those guys are hilarious.

 

Secondly, there are extant burrowing birds. Afaik most of these are seabirds (not sure why that is, but meh). Petrels, prions, and shearwaters are examples.

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Please provide examples.

 

Originally we were just talking birds vs dinos. And I still want to remind you that 3 out of 4 orders of birds didn't make it! I think perhaps this thread has gone off is that we are working with the fallacy that ALL birds survived the KT extinction. That isn't true. Only a very few species survived!

 

http://www.tulane.edu/~bfleury/birds/birdlectures/originflight.rtf

"Most Cretaceous birds disappeared at the end of the Cretaceous, along with the dinosaurs End of the Cretaceous, the world was full of birds, coexisting with an incredible diversity of dinosaurs, many bird-like theropods like Caudipteryx Very poor understanding of the winners and losers among the groups of birds alive at the end of the Cretaceous Of the few that we know about, most joined their ancestors in extinction Hesperornithoformes, Ichthyornithiformes, Enantiornithes, all vanished without a trace Only the loons and some primitive shorebirds crossed the K/T boundary A stunning discovery from Antarctica adds the Anatidae to the growing list of survivors

Vegavis iaai is a distant ancestor of the ducks, geese, and swans Lived 70 mya, alongside T. rex Few species of Neornithes survived the great devastation at the end of the Mesozoic Explosive adaptive radiation (about 10 million years) early in the Tertiary that produced the modern orders of birds"

 

I would agree that crocodiles probably made it thru by 1) living in water which buffered the nuclear winter temps and 2) only having to eat once, or twice, or thrice a year. Wasps would be different. I would speculate that, living in hives, they could make the inside warmer by 1) beating their wings and 2) huddling together. Pretty much how honeybees get thru the winter now.

 

 

 

Foodchain, you are aware that dodos went extinct in historical times from human hunting, right? They have nothing to do with the KT extinction. What you would want to do is look at the species of birds that were alive in the late Cretaceous and compare the species of the enantiornithines, the hesperornithoformes, and the icthyornithoformes (the toothed seabirds) -- all of whom went extict at the KT boundary and the neornithines which did not.

 

 

Yes, My writing skills sometimes don’t catch up with what I am trying to say. I know the dodo died from human activity and related, my point was simply looking at what we can of natural history to derive why some species make it and others don’t.

 

The point about using different species is that they obtain homeostasis and reproduce via different methods. The end goal may be typically the same but they do not conduct life the same way, though with biodiversity you can find a diversity of what survives and what does not. Taking into account that most seriously likely some massive event occur in the earths past that motivated all of these extinctions the amount of variables to take into account that would equate into stress is rather quite large. For instance, what if a species of bird did not have any particular mutations or biology in general that was advantageous, they simply just used environments on the earth that were not hard pressed overall by any changes brought on?

 

I mean going from today, and to minus human activity, we don’t simply have mass extinctions coming from nowhere. Typically the extinction is a product of something in a species environment also, be it disease, predators, or just climate change, species just don’t seem to up and extinct wholly on there own.

 

The best bet in my opinion for finding out why the class made it overall would simply to be having to obtain understanding of natural history that goes outside of just the birds, such as what other life made it, plants, animals, etc... Also using ancestors of birds, and just overall the compilation of such would most likely in my opinion be the only way to find out the why, for it takes into account more or less everything that needs to, rather then just sections of a whole. I think you have to use life more or less in a connection because in my opinion to take all of life away from the planet save for one species might be the end of life unless that specie could do something in time on some level to save being selected against. I mean life radiates out over the planet, it accumulates change in the form of mutation for instance, but it’s the natural selection part, which is overall the environment or the totality of such surrounding an organism or species that selects for or against. So if you have a sudden shift in the environment, what would you expect to have happen?

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my point was simply looking at what we can of natural history to derive why some species make it and others don’t.

 

This sounds like a general statement -- that there are going to be commonalities between the surviving species between different extinction events. BUT, then you note:

 

The end goal may be typically the same but they do not conduct life the same way, though with biodiversity you can find a diversity of what survives and what does not. Taking into account that most seriously likely some massive event occur in the earths past that motivated all of these extinctions the amount of variables to take into account that would equate into stress is rather quite large.

 

And that gets us into differences between mass extinctions.

 

I mean going from today, and to minus human activity, we don’t simply have mass extinctions coming from nowhere. Typically the extinction is a product of something in a species environment also, be it disease, predators, or just climate change, species just don’t seem to up and extinct wholly on there own.

 

DUH! Even today's mass extinction caused by human activity translates to an abrupt and severe change to the environments of species. Instead of massive volcanic eruptions that caused the changes in environments for the Permian-Triassic extinction or the meteor impact that caused the change in environments for the K-T extinction, today we have human activity changing environments and causing extinctions.

 

The best bet in my opinion for finding out why the class made it overall

 

NO. NO. NO. The class did NOT "make it overall". Instead, a very few species of all the birds survived the KT extinction. That's the fallacy we have been laboring under. We have been thinking that all or the vast majority of bird species survived while all the dino species went extinct. That has us chasing for some overall feature of birds that would be different from dinos. Instead, what the data says is that over 70% of bird species went extinct! That is not "made it overall", but rather "a few species survived".

 

So now what you need to look to is not only differences between birds and dinos, but differences between the surviving bird species and the bird species that did not survive.

 

obtain understanding of natural history that goes outside of just the birds, such as what other life made it, plants, animals, etc...

 

Now you are back to the generality. That doesn't work, either. As you noted, there are simply too many differences in the morphology, physiology, and lifestyles of the species that did survive the KT extinction to make a generality for ALL those species.

 

And you can't then extrapolate to other extinctions, because they have entirely different causes and different changes in the environment.

 

The only generality you can make is that larger animals and predators are perhaps the most sensitive to extinction. Because 1) they need more food and 2) are higher up the food chain, this means that anything that disrupts the food chain is going to deprive these species of food.

 

I think you have to use life more or less in a connection because in my opinion to take all of life away from the planet save for one species might be the end of life unless that specie could do something in time on some level to save being selected against.

 

Depends on what the species is. If it is unicellular algae, then it will be fine. Basically, what you need to consider is food source. Either the species must have a very common and large food source -- such as some bacteria that work thru oxidation of iron -- or the species must be photosynthetic so it can make its own food.

 

I mean life radiates out over the planet, it accumulates change in the form of mutation for instance, but it’s the natural selection part, which is overall the environment or the totality of such surrounding an organism or species that selects for or against. So if you have a sudden shift in the environment, what would you expect to have happen?

 

This depends on several factors:

 

1. How major the shift is. If the shift is "sudden" but not severe, there is probably enough variation within the population so that there will be individuals with the requisite traits to survive the new environment.

 

As the shift gets more severe and more fatal for individuals, then survival of the species becomes less likely and extinction more likely. However, not always. Antibiotics were 99.999% fatal to bacteria, but still there were a few resistant individuals that lived and repopulated.

 

2. Whether the food chain collapses or not Antibiotics were very specific for bacteria and the bacteria's food source -- humans -- were not affected. But if the food chain collapses, then there is unlikely to be more exinctions as food sources go extinct.

 

3. Specialization of the species. A species specialized to a particular environment becomes vulnerable to extinction. Partly this is due to purifying selection (a form of natural selection) that reduces genetic variation within the population. Partly it is due to the limitations of having a (relatively) small environment available.

 

 

There may be other factors, but these are the ones I remember off the top of my head.

 

Blue cristal--> Some times just few individuals ( pioneers ) can even start a new species through accidental geographical separation after hundreds or thousands generations.

 

Sayonara--> I take it you meant a new population, rather than a new species.

 

This is actually very rare in higher animals, because they almost invariably have a less tolerant generational viability threshold than things like moss and asexual organisms.

 

Blue cristal was referring to founder events, where you have a single or 2-3 breeding pairs becoming geographically isolated. New species do result. This is rare because 1) getting a single breeding pair isolated does not often happen and 2) accidental death can eliminate the population in the first couple of generations. However, genetic viability is not an issue. Two individuals in a sexually reproducing population typically have about 75% of the total genetic variation of the population.

 

However, allopatric speciation where a larger number of individuals become geographically isolated. And this looks to be the major form of cladogenesis of higher animals. In fact, that is what Punctuated Equilibrium is all about: the fossil record shows that most speciation happened by allopatric speciation.

 

And so i posted that i thought that this and an arms race between species are the only factors i can think of that cause the evolution of higher animals.

 

You forgot sympatric speciation. This is where you have speciation in the same geographical area, but divergence of populations as they exploit different environments (within the geographical area).

 

I was saying it was rare among the higher animals for a few individuals to spontaneously generate a stable population in a new environment (in the way that pioneer plant species do, at least).

 

You need to define "few". If you mean 1-3 breeding pairs in a founder event, then yes. It does happen, however. The many species of Drosophila in the Hawaiian Islands resulted from a founder event. Dobzhansky spent considerable time studying and documenting that.

 

Sorry to undermine the argument, but I don't think this question is a terribly good rebuttal.

 

I don't think you meant "rebuttal", but that the hypothesis that birds don't burrow and, therefore, are differnt from mammals in how they survived the KT extinction doesn't withstand testing. You then went on with some excellent tests for that. I particularly like:

 

Secondly, there are extant burrowing birds. Afaik most of these are seabirds (not sure why that is, but meh). Petrels, prions, and shearwaters are examples.

 

Now, go up and compare that to the bird species that survived the KT extinction! "Only the loons and some primitive shorebirds crossed the K/T boundary" Congrats, Sayonara! You may have found a very plausible hypothesis for why the particular bird species survived the KT impact! They were able to shelter in burrows and thus mitigate the effects of the nuclear winter. This would make them comparable to the small mammals that survived and for the same reason.

 

You should do a bit more research on these birds and look to see if the birds that survived the KT extinction could also have burrowed. If so, then you should write this up for publication.

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Blue cristal was referring to founder events, where you have a single or 2-3 breeding pairs becoming geographically isolated. New species do result. This is rare because 1) getting a single breeding pair isolated does not often happen and 2) accidental death can eliminate the population in the first couple of generations. However, genetic viability is not an issue. Two individuals in a sexually reproducing population typically have about 75% of the total genetic variation of the population.

 

However, allopatric speciation where a larger number of individuals become geographically isolated. And this looks to be the major form of cladogenesis of higher animals. In fact, that is what Punctuated Equilibrium is all about: the fossil record shows that most speciation happened by allopatric speciation.

 

 

touche, ya i didn't realize that she meant pioneer as in just 2 individuals. you could probably do it with just one male and multiple females but ya i agree just 2 people is not very likely to work.

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You need to define "few".

That's for blue-cristal to define really, in conjunction with exactly what order of complexity the organisms are which are being proposed as founders.

 

If you mean 1-3 breeding pairs in a founder event, then yes. It does happen, however. The many species of Drosophila in the Hawaiian Islands resulted from a founder event. Dobzhansky spent considerable time studying and documenting that.

I understand that it happens, and my post was not intended to suggest this is not the case. I did specify "higher organisms", and I do not consider drosophila to be particularly well suited to that category.

Others may disagree I suppose, so this is clarification for those who do: the order of complexity which I am considering in the likelihood of a founder event is equal to or greater than the order of complexity for the groups we have been discussing throughout the thread (birds etc).

 

 

I don't think you meant "rebuttal",

Meh, it was late, brain functions, leave me alone, etc.

 

You should do a bit more research on these birds and look to see if the birds that survived the KT extinction could also have burrowed. If so, then you should write this up for publication.

Let me dig out my typewriter. By golly, Nature won't know what hit them!

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