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Fossil Bird With Cool Teeth


Scylla

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I especially appreciate that the writer of the second article referred to the adaptive radiation in the beaks of "Darwin's finches" in support of the hypothesis. Interestingly, the toothless beak itself probably evolved in part as a generalized manipulator with a lower metabolic cost than heavy dentition.

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

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The birds in the article had teeth because their immediate ancestors had teeth. They are adapted to whatever feeding strategy that they used to survive.

Modern birds immediate ancestor did not have teeth, an adaptation to whatever feeding strategy they used, so modern birds do not have teeth (once an organ is lost, it does not generally re-appear, think gills in land animals). Remember birds to it on the chin (or the bill) during the Cretaceous extinction, and toothed birds went extinct, not necessarily because teeth were worse then modern bills, but more likely through random chance. The survivors then speciated and evolved based on what charactertistics they could modify, in this case beaks.

It shouldn't be assumed that beaks are better then teeth for flying organisms. I suspect that bats and pterosaurs would strongly argue against a superiorityof beaks.

Correct me where I am wrong in my thinking.

Brent Ashcraft

.

ashcraft, brent allen

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The birds in the article had teeth because their immediate ancestors had teeth. They are adapted to whatever feeding strategy that they used to survive.

Modern birds immediate ancestor did not have teeth, an adaptation to whatever feeding strategy they used, so modern birds do not have teeth (once an organ is lost, it does not generally re-appear, think gills in land animals). Remember birds to it on the chin (or the bill) during the Cretaceous extinction, and toothed birds went extinct, not necessarily because teeth were worse then modern bills, but more likely through random chance. The survivors then speciated and evolved based on what charactertistics they could modify, in this case beaks.

It shouldn't be assumed that beaks are better then teeth for flying organisms. I suspect that bats and pterosaurs would strongly argue against a superiorityof beaks.

Correct me where I am wrong in my thinking.

Brent Ashcraft

.

Your thinking is pretty sound, but we cannot really tell if beaks were accidentally favored or were really better. Turtles and some dinosaurs had beaks too so I think that parallel evolution shows there must be an advantage for beaks in some cases. Then there are those goose "teeth" that are really just tooth-like projections on the bill...

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A bird's beak is not just a feeding apparatus; it is also the only tool it has to use to manipulate its world: birds may be bipedal, but they don't have hands! Their sophisticated level of 'dexterity', enhanced by a long, hyper flexible neck, most certainly has value in the natural selection arena. Though often overlooked, it cannot be overstated how utterly vital it is that a bird maintain their plumage by cleaning, preening, and re-'zipping' their feathers. Birds spend more than half of their waking hours on feather maintenance; it is life-or-death. A beakless mouth full of teeth simply could not do the job. How the toothed birds managed for so long is a mystery; perhaps flight was but a secondary consideration to how they lived.

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

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A bird's beak is not just a feeding apparatus; it is also the only tool it has to use to manipulate its world: birds may be bipedal, but they don't have hands! Their sophisticated level of 'dexterity', enhanced by a long, hyper flexible neck, most certainly has value in the natural selection arena. Though often overlooked, it cannot be overstated how utterly vital it is that a bird maintain their plumage by cleaning, preening, and re-'zipping' their feathers. Birds spend more than half of their waking hours on feather maintenance; it is life-or-death. A beakless mouth full of teeth simply could not do the job. How the toothed birds managed for so long is a mystery; perhaps flight was but a secondary consideration to how they lived.

Sure, and I'll bet some of those bills (toucans maybe?) are also subject to sexual selection. Also bills are used in communication in cases such as feeding seagull chicks where the chick signals its is ready to eat and the bill signals where to signal...

http://www.dustincurtis.com/how_niko_tinbergen_reverse_engineered_the_seagull.html

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A bird's beak is not just a feeding apparatus; it is also the only tool it has to use to manipulate its world: birds may be bipedal, but they don't have hands! Their sophisticated level of 'dexterity', enhanced by a long, hyper flexible neck, most certainly has value in the natural selection arena. Though often overlooked, it cannot be overstated how utterly vital it is that a bird maintain their plumage by cleaning, preening, and re-'zipping' their feathers. Birds spend more than half of their waking hours on feather maintenance; it is life-or-death. A beakless mouth full of teeth simply could not do the job. How the toothed birds managed for so long is a mystery; perhaps flight was but a secondary consideration to how they lived.

This reminds me of the bumblebee conundrum. Engineeers said that it was impossible for bumblebees to fly, only problem was nobody told the bumblebees.

But they did survive, and quite well, with teeth. toothlessness, as I recall, is a late development in birds. Meaning they got by for millions of years by preening their feathers with their teeth. Maybe preening not as important as thought? Or perhaps can preen better with teeth then thought?

It is my uneducated opinion that if the impactor had not wiped out most if not all toothed birds, they still would be quite common today.

Brent Ashcraft

ashcraft, brent allen

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By the end of the Mesozoic, the subclass Neornithes (modern birds) was ascendant; my thought-experiment is that something fundamental in the environment had changed, something that put the toothed birds at an evolutionary disadvantage. It may be that one factor was competition for new resources (flowering plants come to mind), and that the final full conquest of the air by those better adapted to flight* as a way of life sealed the fate of a more earth-bound members of the clade Avialae. I realize that this is a dizzying circle-of-proof, but the question begs informed speculation, and I am averse to embracing catastrophe as an explanation when unexceptional evolutionary processes will do.

*(More centralized mass [teeth are heavy], better ability to take advantage of various food resources, more effective maintenance of plumage...)

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

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By the end of the Mesozoic, the subclass Neornithes (modern birds) was ascendant; my thought-experiment is that something fundamental in the environment had changed, something that put the toothed birds at an evolutionary disadvantage. It may be that one factor was competition for new resources (flowering plants come to mind), and that the final full conquest of the air by those better adapted to flight* as a way of life sealed the fate of a more earth-bound members of the clade Avialae. I realize that this is a dizzying circle-of-proof, but the question begs informed speculation, and I am averse to embracing catastrophe as an explanation when unexceptional evolutionary processes will do.

*(More centralized mass [teeth are heavy], better ability to take advantage of various food resources, more effective maintenance of plumage...)

There in lies the crux of our differences. I think most species hold their niche because they are in it, and they have numbers. A species may get a mutation that better allows them to fill a niche then the current occupiers, but (in my opinion) it can't become common enough to drive the other speceis out. Eusmilus eventually drove Thylacosmilus to extinction (it appears) , but they had a huge base population to draw from (as both of them did). If you took a few Eusmilus and put them on South America by themselves, versus the full population of Thylacosmilus, the extinction would have been reversed.

In my opinion, it takes an extinction event, or at least a major catastrophe, to lower the population of the dominant species to where they become vulnerable to other species that are competing on the edge for some of their niche.

I am a catastrophist through and through.

Brent Ashcraft

ashcraft, brent allen

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I also believe in the role catastrophe plays in sculpting the course of evolution, I just don't name it as the definitive cause until the braided paths of other natural forces are considered and found wanting.

The best buffer against extinction due to catastrophe is a widely distributed population, yes? It follows that mobility and adaptability are key to genetic near-immortality in the face of such events, so I like to follow that line of speculation for clues first.

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

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There is very little evidence that organisms, particularly large land animals, change over time. They seem to exist as a speceis for whatever period of time, then are gone completely from the fossil record, replaced by someting else. If change does occur this way, then an extinction is generally caused by a cataclysmic event, at least to that species. This then allows some other species to rapidly evolve into that niche and hold it as their own until the next cataclysm. I am speaking of punctuated equilibrium of course. The gradual change of one species into another, filling new niches as they get mutations making them better suited then what was there seems like a good model. Unfortunately, fossil evidence dosn't support that this is happening.

Robert T. Bakker notes in his book "The Dinosaur Heresies" a mass extinctions exhibit the following traits:

-strikes land and sea

-strikes hardest at large fast-evolving families on land

-hits small animals less hard

-leaves large cold blooded organisms untouched

does not strike at freshwater swimmers- which he notes are cold blooded

strikes plant eaters more severly then plants

He wrote this in 1989, I don't know if all these are still considered as correct, but it is certainly an interesting way to look at an extinction event.

Brent Ashcraft

ashcraft, brent allen

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Good discussion. Could climate/environmental change be considered a catastrophic event?

Just thinking of the peppered moth in England where soot from coal fired factories enabled the darker species

to surpass the light species in a matter of a few decades. Moving from 2% of the population to 98%.

I'm just using this as an example that we can observe and possibly apply to the natural environment.

It's hard to remember why you drained the swamp when your surrounded by alligators.

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Industrial melanism was only catastrophic to the white moth form, the black moth form liked it fine. In my opinion, this allele kept the event from being catastrophic to the moth species, reducing its number to become vulnerable to extinction either from the event itself, or by "eviction" from a new species.

Brent Ashcraft

ashcraft, brent allen

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In my thinking a "catastrophe" (in the geologic sense) is a (relatively) sudden event effecting a large area (greatly altering the environment), and occurring so infrequently that there can be no genetic pre-adaptation for a specie's survival, except as might arise by chance over the intervening period of relative equilibrium. An unpleasant surprise, as it were. This will certainly jump-start the process of adaptive radiation, but it cannot be the only (or even primary) engine. Ask yourself how many species have gone extinct: it is a continuous process, and there just not enough catastrophes (per my preceding definition) to go around.

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

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In my thinking a "catastrophe" (in the geologic sense) is a (relatively) sudden event effecting a large area (greatly altering the environment), and occurring so infrequently that there can be no genetic pre-adaptation for a specie's survival, except as might arise by chance over the intervening period of relative equilibrium. An unpleasant surprise, as it were. This will certainly jump-start the process of adaptive radiation, but it cannot be the only (or even primary) engine. Ask yourself how many species have gone extinct: it is a continuous process, and there just not enough catastrophes (per my preceding definition) to go around.

Just to play the Devil's Advocate-

Are you sure most extinctions are not caused by a catastrophic geologic event? Logically this would seem true, but do studies actually show this? We can't even agree when ALL dinosaurs went extinct, let alone one species.

To me, catastrophic is any event that rapidly lowers the numbers of individuals within a species to potential extinction status, it has to occur rapidly enough so that they cannot evolve. This could be a relatively small event if the species is not widespread or adaptable, like a panda, or could have to be an extremely serious event to overcome whole families of fluorishing beasties, such as dinosaurs and mammals.

Brent Ashcraft

ashcraft, brent allen

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Well, the 'life span' for all fossil species is calculated to be between 1/2 million to 5 million years (Simpson, 1952).

Even allowing for the fact that this is calculated as an average, that's a lot of catastrophes; it seems to me that there is a significant background extinction rate that has no correlation to large scale catastrophes.

I certainly do not maintain that there have not been periodic, sudden, grand-scale turnovers, and that the rates of speciation immediately following them have been extremely high (and that this is where the profound changes in body-plan are most noticeably manifest); I just think that, most of the time, species come and go as response to the most reliably dynamic influence within any ecosystem: internal competitive pressure by every biological member of the community.

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

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... it has to occur rapidly enough so that they cannot evolve ...

Hi Brent,

We've had this discussion before I think. Extinction does not have to occur rapidly, nor does it require a cataclysmic/catastrophic event. Extinction is just as likely, probably more so, to be the result of a long, slow, decline. Continental drift is a good example of a very slow process that has been causing extinctions since the first spark of life on this planet. Evolution itself can cause extinction, a mutation within one species can affect instability throughout an entire ecosystem, driving other species to extinction. The tendency of species to have a limited life spans is known as the normal extinction rate and while there is controversy over the correct way to calculate it, especially between different taxomonic groups, there is little debate about its existence.

Are you sure most extinctions are not caused by a catastrophic geologic event? Logically this would seem true, but do studies actually show this?

As opposed to listing all studies into the extinction rate of various taxonomic groups I would instead point you towards John Lawton and Robert May's Extinction Rates. The book is the best available text on the subject I know of, it provides both an overview and in depth coverage of the study of extinction. However, if logically it seems true that most extinctions are not caused by a catastrophic geological event then the burden of proof against said logic is on you as the doubter. Are there studies that show that this belief is incorrect?

"They ... savoured the strange warm glow of being much more ignorant than ordinary people, who were only ignorant of ordinary things."

-- Terry Pratchett

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Hi Brent,

We've had this discussion before I think. Extinction does not have to occur rapidly, nor does it require a cataclysmic/catastrophic event. Extinction is just as likely, probably more so, to be the result of a long, slow, decline.

I agree that it could be slow, but I suspect it more often fairly rapid (I am speaking in geologic time frames). Regardless, it is my position that it generally starts with some catastrophic event to the species. Cheetahs are hanging on by a thread, they have survived by this thread for some 10,000 years. Whatever caused the decline of the males was surely catastrophic.

Continental drift is a good example of a very slow process that has been causing extinctions since the first spark of life on this planet. Evolution itself can cause extinction, a mutation within one species can affect instability throughout an entire ecosystem, driving other species to extinction. The tendency of species to have a limited life spans is known as the normal extinction rate and while there is controversy over the correct way to calculate it, especially between different taxomonic groups, there is little debate about its existence.

Continental drift is a slow process, but what it does to cause extinctions may not be. A continent slamming into another opening a new travel corridor would be a rapid event, and a fairly cataclysmic one at that.

Not all species display this "extinction rate" I am no statistical expert, but I have always considered it an artifact of how the system works. I suspect that ecosystems over time are equivalent to each other, changing at a relatively stable rate. This change is presumably what is causing the extinctions, so the extinctions will reflect a periodicity because of this.

Can you give an example of a single mutation cause extinctions in other speceis within a given system? I would love to have that for class.

As opposed to listing all studies into the extinction rate of various taxonomic groups I would instead point you towards John Lawton and Robert May's Extinction Rates. The book is the best available text on the subject I know of, it provides both an overview and in depth coverage of the study of extinction. However, if logically it seems true that most extinctions are not caused by a catastrophic geological event then the burden of proof against said logic is on you as the doubter. Are there studies that show that this belief is incorrect?

That book is $85! Do you know what a teacher makes? True as far as if I was trying to disprove it, but my intent was to get others to look at the paradigm in a different way.

Remember, when I am saying "catastrophic event", I am saying it in relation to that species. It is my assertion that it takes a pretty good "knock" to take a species out. It doesn't have to kill them immediatly, but reduce their numbers to the point that they have to compete for the niche again (speceis hold niches by exclusion, not warfare in most cases). Then they have to deal with other organisms adaptations, and probably more importantly, random chance.

Brent Ashcraft

ashcraft, brent allen

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Brent,

I think the division between our views is merely a matter of scale; this led me, in my last couple posts, to try and define what I mean when I say "catastrophe". It is clear to me now that we are just describing different parts of the same elephant! Nothing that I have postulated is mutually exclusive of anything you have proposed, and I have always, and will continue to, enjoy and benefit from our discussions. Some day, I'm going to take you to dinner!

Chas.

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

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Brent,

I think the division between our views is merely a matter of scale; this led me, in my last couple posts, to try and define what I mean when I say "catastrophe". It is clear to me now that we are just describing different parts of the same elephant! Nothing that I have postulated is mutually exclusive of anything you have proposed, and I have always, and will continue to, enjoy and benefit from our discussions. Some day, I'm going to take you to dinner!

Chas.

Thanks, look forward to it! At 6'5" and 350 pounds (although decreasing), you may want to reconsider!

Brent Ashcraft

ashcraft, brent allen

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That book is $85! Do you know what a teacher makes? ...

Hi Brent,

My mother has been a high school biology teacher for the past 23 years, so yes I'm aware of the limitations concerning a teacher's salary. I'm a university student with even less income and I managed to get my hands on a copy of the book just fine, for free. The university libraries here didn't have a copy so I used interlibrary loan at my local county library and they had a copy for me within a week.

If you absolutely must buy a copy it is easily sourced online for far less than the Amazon list price. ABE books has a copy for $12 in good condition.

"They ... savoured the strange warm glow of being much more ignorant than ordinary people, who were only ignorant of ordinary things."

-- Terry Pratchett

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Just ordered it, finished reading "my inner fish", a little disappointed on the depth, but I suspect this will be plenty challenging.

26 years? I'll never last that long. My first career spanned nearly two decades, and I have over a decade into this one (teaching).

Brent Ashcraft

ashcraft, brent allen

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Just ordered it, finished reading "my inner fish", a little disappointed on the depth, but I suspect this will be plenty challenging.

26 years? I'll never last that long. My first career spanned nearly two decades, and I have over a decade into this one (teaching).

Brent Ashcraft

Hi Brent,

Cool I hope you enjoy it! Growing up with a teacher as a parent I developed a tremendous amount of respect for the career. Bravo to you and everything you do for your students!

:thumbsu:

"They ... savoured the strange warm glow of being much more ignorant than ordinary people, who were only ignorant of ordinary things."

-- Terry Pratchett

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