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The great Extinction and its survivors


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#16    Hehe

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Posted 24 January 2006 - 11:54 AM

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All of today's flightless birds evolved from birds that could fly.


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The flyingfish?  Maybe.  But they have yet to evolve ways of surviving ouside water for extended periods of time.


Ok.. so from what i gather, the general trend is that more animals tend to loose the ability of flight, than animals evolve to gain flight, in the last say... 60 million years? Why is that?
Is there a rational explanation with good proof to describe it?

Insects: Anything evolving to gain flight. The stick insect "Phasma gigas" lost its ability and "appears" to be "re-evolving" its wings (Contrary to Dollo's Law).
As far as i know i only know of insects that somewhere along the line lost their ability of flight. Eg.  Lice, fleas, some beetles (All belong to Pterygotes)

Can't scientists design an experiment to accelarate the "re-evolving" of wings of the Phasma gigas stick insect. (http://www.astrobio....article&sid=358)

We must be living in a dull era of evolution as nothing constructive seem to evolve. (Oh wait, they think we might be getting smarter)


#17    Sofia Alexandra

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Posted 24 January 2006 - 03:06 PM

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We must be living in a dull era of evolution as nothing constructive seem to evolve. (Oh wait, they think we might be getting smarter)

rolleyes.gif
Evolution happens continually, but it takes a long time and it's nothing you notice in just one lifetime. And if you don't think there's anything interesting happening right now, check back in some 10000 years.



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#18    frogfish

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Posted 24 January 2006 - 09:16 PM

evolution is a slooooooooow process...

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#19    Hehe

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Posted 25 January 2006 - 07:56 AM

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evolution is a slooooooooow process...

I knoooooww.
Cant you see the trend though (loosing and not gaining)?  Or is it sooo slooowww that you cant?

According to this guy evolution is even slower,
Primate evolution: http://www.evolutionfairytale.com/forum/in...p?showtopic=596
It adresses the human/primate genome similarities and looks at what makes us human on a genetic level.
Quite interesting even though the website adress sounds a bit... fundamental unsure.gif
Scientific info nonetheless.

Quote


rolleyes.gif
Evolution happens continually, but it takes a long time and it's nothing you notice in just one lifetime. And if you don't think there's anything interesting happening right now, check back in some 10000 years.

Im guessing that you're implying that 10000 years ago we were stupid cavemen and now we are intelligent. Im sure you're not implying that 10000 years ago there were less biodiversity than today, although it would seem logical how evolution tend create new families of species.

According to this site, 10000 (500 generations) years is too little for humans to evolve much in the line of intelligence.
http://www.anth.ucsb.edu/projects/human/epfaq/holocene.html

Edited by Hehe, 25 January 2006 - 08:16 AM.


#20    frogfish

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Posted 25 January 2006 - 08:14 PM

Nice site thumbsup.gif

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#21    capeo

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Posted 28 January 2006 - 10:27 PM

HeHe, one thing that needs to cleared up is your idea of devolution and evolution.  You can't think of natural selection as causing species to evolve towards some goal of perfection.  Perfection as defined by natural selection is being suited to survive long enough to pass on genes.  It's entirely random.  Take Crocodylia for example, while its untrue to say they haven't changed (i.e. haven't faced selection) their general morphology is amazingly consistent for millions of years.  They have dominated the shoreline niche they exist in, are very successful, and thus haven't needed vast adaptions.  Just bear in mind these adaptations come about from constantly ongoing minute genetic variations (its actually quite a bit more complex than that but that's a whole other post).  These variations are passed on if they benefit the animal's survival in its environment (i.e. if it lives long enough to reproduce).  If there isn't a vast change in environment an animal can stay morphologically similar for millions of years.  Anyhow this is very protracted.  I'd suggest going to library for the for more complete picture of genetics.  You'd be better served there than here.

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#22    Hehe

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Posted 29 January 2006 - 09:41 AM

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HeHe, one thing that needs to cleared up is your idea of devolution and evolution.  You can't think of natural selection as causing species to evolve towards some goal of perfection.  Perfection as defined by natural selection is being suited to survive long enough to pass on genes.  It's entirely random.  Take Crocodylia for example, while its untrue to say they haven't changed (i.e. haven't faced selection) their general morphology is amazingly consistent for millions of years.  They have dominated the shoreline niche they exist in, are very successful, and thus haven't needed vast adaptions.  Just bear in mind these adaptations come about from constantly ongoing minute genetic variations (its actually quite a bit more complex than that but that's a whole other post).  These variations are passed on if they benefit the animal's survival in its environment (i.e. if it lives long enough to reproduce).  If there isn't a vast change in environment an animal can stay morphologically similar for millions of years.  Anyhow this is very protracted.  I'd suggest going to library for the for more complete picture of genetics.  You'd be better served there than here.

Please dont insult my intelligence, but thanks for the rudementary lesson in genetics and evolution. I must admit genetics is not my strong point as i am more interested in human physiology and biochemistry, but i did complete 3rd year genetics and and i understand the main theories.  Bear in mind that you are the first one to mention "devolution" here. Was i not clear enough for you? What i said was that the forces of natural selection (be it mutatonal change or environmental change) tend to favour the change of "flight-abled" to flightless animals in recent history.
The reason i am asking this is that for the life in me i cant imagine how eons ago the first animals took to the air. Guess that is why no-one can give me a scientific article on how the mechanism of flight evolved (It is a hot topic of of debate for scientists).
All i get is everyones opinions and ideas (speculation), and no-one seems to agree on a common mechanism. Although Richard Dawkins did try valiantly in one of his books (think Ancestor's tale).
Cursorial and arboreal are the only two mechanisms to explain how flight evolved but evidence for either are.... well circumstantial and purely speculative.

Edited by Hehe, 29 January 2006 - 09:44 AM.


#23    Rahl

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Posted 29 January 2006 - 04:58 PM

I do not look for frogfish to provide any answers, because he has none  with his schoolboy knowledge he knows very little but is full of opinions and attitude. . He is a  narcissistic arrogant little  person who thinks that insulting people impresses people into thinking he knows anything. I am pleased to never hear from this fool again . /ignore list frogfish

Edited by Rahl, 29 January 2006 - 06:15 PM.

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#24    frogfish

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Posted 29 January 2006 - 07:31 PM

With your inability to understand evoluion and biology, Rahl, you should be welcome to corrections.

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I do not look for frogfish to provide any answers, because he has none with his schoolboy knowledge he knows very little but is full of opinions and attitude. . He is a narcissistic arrogant little person who thinks that insulting people impresses people into thinking he knows anything. I am pleased to never hear from this fool again . /ignore list frogfish


If you choose to ignore the facts, fine...But do not come back if you can't handle corrections. Its science - It's called peer review.

Edited by frogfish, 29 January 2006 - 07:33 PM.

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#25    Hehe

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Posted 29 January 2006 - 08:15 PM

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I do not look for frogfish to provide any answers, because he has none  with his schoolboy knowledge he knows very little but is full of opinions and attitude. . He is a  narcissistic arrogant little  person who thinks that insulting people impresses people into thinking he knows anything. I am pleased to never hear from this fool again . /ignore list frogfish

Quote


With your inability to understand evoluion and biology, Rahl, you should be welcome to corrections.
If you choose to ignore the facts, fine...But do not come back if you can't handle corrections. Its science - It's called peer review.

rolleyes.gif  sleepy.gif Ugh childish banter. How about staying on topic. Someone should create a topic named "The Cockpit" so that these cockfights can be settled. Betting should be allowed w00t.gif

Edited by Hehe, 29 January 2006 - 08:23 PM.


#26    frogfish

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Posted 31 January 2006 - 12:55 AM

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Ugh childish banter. How about staying on topic. Someone should create a topic named "The Cockpit" so that these cockfights can be settled. Betting should be allowed

Me like it yes.gif

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#27    FrothyDog

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Posted 31 January 2006 - 05:05 PM

i have an idea, and i'm not sure if i heard it somewhere or just in my own little head:

there was definitely some kind of world-changing event, probably an impact, as evidenced by the KT boundary.  i think perhaps it reduced the amount of oxygen in the atmosphere, and killed off anything that could not quite handle the reduced oxygen intake.  perhaps the dino/bird connection did not begin with flight, but with the smaller size and better respiratory system.  with smaller size, and perhaps lighter bones for oxygen storage, they may have taken to the trees for safety, and later, the air.

let me know if you guys have heard it somewhere, or just what you think about that.

also, that extinction was actually pretty small, it only killed off 1 or 2% of life forms.  but the big stuff definitely went, so we give it more thought than the permian extinction, which killed off 98% of life.


#28    capeo

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Posted 31 January 2006 - 08:28 PM

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I knoooooww.
Cant you see the trend though (loosing and not gaining)?  Or is it sooo slooowww that you cant?


Chill HeHe,
I mistook your losing and gaining idea.  Also, I wasn't insulting your intelligence but you weren't using concepts of evolution correctly, or at least not clearly enough to me that I gathered you understood them.  Just trying to help.  

As for where birds came from:

http://news.bbc.co.uk/2/hi/science/nature/2684927.stm

http://www.china.org.cn/english/culture/118778.htm

http://palaeo.gly.bris.ac.uk/dinobase/feat...saurs_final.pdf

http://english.people.com.cn/200210/21/eng...21_105389.shtml

http://www.findarticles.com/p/articles/mi_...010/ai_n8915231

http://news.nationalgeographic.com/news/20...ird_fossil.html

As you see China is a hotbed of feathered dinos and there may now be sufficient evidence coming to light that suggests birds probably existed during the time of dinosaurs in great abundance and simply outlasted them.

As for flightless birds.  They can only evolve where there are minimal land predators (the exception being larger and more ancient forms such as the emu and ostrich) and these are very isolated locals.  I'm no expert on them but flightless bird evolution should be able to happen rather quickly as a population spends more time on the forest floor.  The naturally smaller winged birds would quickly be selected for their ability to move and forage better.  These types morphological changes can happen quickly as is evidenced by studies of sparrow populations that where seperated fairly recently (13,00 years):

http://elibrary.unm.edu/sora/Auk/v110n04/p0844-p0856.pdf

I don't know of any evidence that would point to more birds becoming flightless in recent millenia than in the past but either way, if there's a niche, something will fill it.

Edited by capeo, 31 January 2006 - 08:30 PM.

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#29    frogfish

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Posted 01 February 2006 - 03:05 AM

Sorry Frothy, but bones don't store oxygen...only calcium. PTH releases it. The KT event wiped out all the larger lifeforms that could not sustain, he dinos, the pterosaurs, and the marine behemoths. They took up to much 'space', and could not survive on the damaged ecosystem. The voids left by these animals were filled by their evolutionary ancestors, the birds, and the mammals. The mammals grew larger to become the dominant species. Flightless birds are just a branch of birds that evolved without the need for flight, due to their environment or size.

If a disaster was to happen today, all the large lifeforms (as in space) would die out aka. the mammals...

Clearer?

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#30    Hehe

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Posted 01 February 2006 - 08:24 PM

I think what Frothy was trying to say was that: Because the big dinosaurs had such small nostrils (minimal air intake) there had to be more oxygen (higher pressure). I donno frogfishy, do you want to insult him by pointing out that bones dont store oxygen, sure is juvenile (but i see that you attend biology, at least you know what PTH is, oh yeah, ever heard of Calcitonin and Vit D). Why would the the KT event only kill the bigger animals? Was it less... food, air or water? Specifics here now, and facts... not speculations FACTS!! Now the standard answer will be that the KT event killed off the majority of plant life so that only the small herbivores and carnivores survived.... ok why did the small ones survive... ok they survived off the dead big ones, how long did this last? Again FACTS are always better than speculation, otherwise i can speculate all day. w00t.gif  rolleyes.gif

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Flightless birds are just a branch of birds that evolved without the need for flight, due to their environment or size.


What part of the environment or their size drove the first animals to take on flight? Facts would be nice and since this seems to be your niche, im sure you will point them out.

Capeo... thanks for those links. I will have a look, im sure i will find those speculations and facts interesting.

Edited by Hehe, 01 February 2006 - 08:44 PM.





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