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Author Topic:   Are flightless birds a reversion?
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 16 of 44 (419254)
09-01-2007 8:31 PM
Reply to: Message 15 by molbiogirl
09-01-2007 8:21 PM


Re: Ostrige... Ostrage...
I think it's an honest comparison, ... minus the issue of the Coelacanths not evolving legs etc.
Why should we be surprised to find existing descendants of intermediates that continue to exhibit intermediate morphology?
Enjoy.
Edited by RAZD, : ...

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we are limited in our ability to understand
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jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 17 of 44 (419255)
09-01-2007 8:32 PM


Please Gang, ignore the nonsense
Please gang. Can we head this back towards the topic and not get drawn down "silly rabbi" holes? We all know that "Kicks are for Trids."

Aslan is not a Tame Lion

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 18 of 44 (419256)
09-01-2007 8:37 PM
Reply to: Message 12 by molbiogirl
09-01-2007 8:07 PM


Re: wing vs limb elements
Nice article, but hard to look at those hand\wing bones ...
What do we have for Ratitae or Palaeognathae fossils?
Thanks

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Replies to this message:
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molbiogirl
Member (Idle past 2641 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 19 of 44 (419258)
09-01-2007 8:49 PM
Reply to: Message 18 by RAZD
09-01-2007 8:37 PM


Re: wing vs limb elements
Well, there's this:
The evolutionary radiation of modern birds (Neornithes): reconciling molecules, morphology and the fossil record Zoological Journal of the Linnean Society Volume 141 Issue 2 Page 153-177, June 2004
It has a lot of links re: Palaeognathae fossils (and some pics too).
And there's this:
Analyses of Mitochondrial DNA Nest Ratite Birds within the Neognathae: Supporting a Neotenous Origin of Ratite Morphological Characters
Anna Harlid, Ulfur Arnason Proceedings: Biological Sciences, Vol. 266, No. 1416 (Feb. 7, 1999), pp. 305-309
Final sentence of abstract:
Thus, the result is inconsistent with the traditional understanding of a basal avian divergence between Palaeognathae and Neognathae. The findings suggest that the morphological characteristics of the ratites are secondarily acquired, probably through neoteny and that the ratites are descendants of flying, neognathous ancestors.
Edited by molbiogirl, : found ratites

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molbiogirl
Member (Idle past 2641 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 20 of 44 (419261)
09-01-2007 9:11 PM
Reply to: Message 18 by RAZD
09-01-2007 8:37 PM


Ratites
Found this:
Evidence for speciational change in the evolution of ratites (Aves: Palaeognathae) Biological Journal of the Linnean Society Volume 80 Issue 1 Page 99-106, September 2003
Pulled this quote:
We can wonder about the proximal factors (Cubo et al., 2000; Cubo, 2000) underlying the similar patterns of character evolution in the different wing bones of ratites. Ratite wing bones are under-developed and this has been interpreted by Cubo & Arthur (2000) as a case of paedomorphosis (the retention of ancestral juvenile character states in adult stages of descendants, Gould, 1977). Considering that the development of forelimbs is delayed relative to the development of hindlimbs in birds (Carrier & Leon, 1990), either the truncation or the retardation of somatic development (heterochrony) is likely to produce reduction of the size of all wing bones by correlated development (Cubo & Arthur, 2000). Heterochronic changes can be instantaneous in terms of geological time (Gould, 1977) and they are likely to produce patterns of speciational character evolution. Ratite wing bones do not play a function in locomotion, they do not undergo adaptation linked to flight, and this would have contributed to preserve the pattern of speciational character evolution generated by heterochronic changes.

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 21 of 44 (419265)
09-01-2007 9:29 PM
Reply to: Message 20 by molbiogirl
09-01-2007 9:11 PM


Re: Ratites and neoteny
Neoteny strikes again eh?
This would tend to indicate that the flightless aspect is devolved from flying ancestors, which would tie in with previous posts on bird evolution (by arach) suggesting that all current birds evolved from a marine type bird (IIRC) that survived the KT extinction event.
Thanks

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we are limited in our ability to understand
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RebelAAmericanOZen[Deist
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This message is a reply to:
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jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 22 of 44 (419269)
09-01-2007 9:41 PM
Reply to: Message 21 by RAZD
09-01-2007 9:29 PM


Re: Ratites and neoteny
But it looks like some of the ancestors of todays examples go back before the KT boundary, if they actually do reach back as far as some claim.
Wiki entry on Paleognathae
Paleognaths probably descended from a common ancestor in the late Cretaceous period on the supercontinent of Gondwana.

Aslan is not a Tame Lion

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Replies to this message:
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Rob 
Suspended Member (Idle past 5848 days)
Posts: 2297
Joined: 06-01-2006


Message 23 of 44 (419270)
09-01-2007 9:43 PM
Reply to: Message 15 by molbiogirl
09-01-2007 8:21 PM


Re: Ostrige... Ostrage...
molbiogirl:
Is this your version of "Coelacanths are unchanging forms that show no evidence of evolution" aka "living fossils refute evolution"?
I don't know if living fossils refute evolution or not. They may well show some devolution; but, they certainly do not show evolution at the level of chemical origins.
Edited by Rob, : No reason given.
Edited by Rob, : No reason given.
Edited by Rob, : No reason given.
Edited by Rob, : No reason given.

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jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 24 of 44 (419276)
09-01-2007 10:02 PM
Reply to: Message 23 by Rob
09-01-2007 9:43 PM


More off topic nonsense from Rob.
Come on Rob. Will you EVER post something relevant or on topic?
This thread, in case you missed it, is "Are flightless birds a reversion?"
Try for once to get in step.

Aslan is not a Tame Lion

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 Message 23 by Rob, posted 09-01-2007 9:43 PM Rob has replied

Replies to this message:
 Message 25 by Rob, posted 09-01-2007 10:20 PM jar has replied

  
Rob 
Suspended Member (Idle past 5848 days)
Posts: 2297
Joined: 06-01-2006


Message 25 of 44 (419282)
09-01-2007 10:20 PM
Reply to: Message 24 by jar
09-01-2007 10:02 PM


Re: More off topic nonsense from Rob.
jar:
Come on Rob. Will you EVER post something relevant or on topic?
This thread, in case you missed it, is "Are flightless birds a reversion?"
I believe I said that I do not know... and then added; they may show reversion. I only used different words. That was my two cents on the matter... and then I politely pointed to the related topic. It's not like I addressed it here.
Will you ever stop asking logically fallacious questions like, 'Have you stopped beating your wife yet'?
Let me try your technique though. It seems to be tolerated by the admins...
Jar, have you always had control issues?
Edited by Rob, : No reason given.

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jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 26 of 44 (419283)
09-01-2007 10:26 PM
Reply to: Message 25 by Rob
09-01-2007 10:20 PM


Re: More off topic nonsense from Rob.
I'm sorry Rob but nothing in the linked thread was related to anything in this topic and no, you did not offer any information on the topic.
In addition I have never had "control issues" which again is irrelevant to anything in this topic.

Aslan is not a Tame Lion

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 Message 25 by Rob, posted 09-01-2007 10:20 PM Rob has not replied

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molbiogirl
Member (Idle past 2641 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 27 of 44 (419284)
09-01-2007 10:32 PM
Reply to: Message 26 by jar
09-01-2007 10:26 PM


Re: More off topic nonsense from Rob.
It's not just you, jar.
Rob is posting bare links to his PNT in other threads, too.

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Rob 
Suspended Member (Idle past 5848 days)
Posts: 2297
Joined: 06-01-2006


Message 28 of 44 (419287)
09-01-2007 10:39 PM
Reply to: Message 27 by molbiogirl
09-01-2007 10:32 PM


Re: More off topic nonsense from Rob.
EVC rule: Bare links with no supporting discussion should be avoided. Make the argument in your own words and use links as supporting references.
molbiogirl:
It's not just you, jar.
Rob is posting bare links to his PNT in other threads, too.
Sometimes they cannot be avoided, but I have deleted all links just to accomodate you and yours...
Edited by Rob, : No reason given.

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 29 of 44 (419290)
09-01-2007 11:12 PM
Reply to: Message 22 by jar
09-01-2007 9:41 PM


Re: Ratites and neoteny
But it looks like some of the ancestors of todays examples go back before the KT boundary, if they actually do reach back as far as some claim.
and
quote:
The Paleognathae or paleognaths ("old jaws") are one of the two living superorders of birds. The other living superorder is Neognathae.
All the other (living) birds are in the other superorder.
Interesting.

Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


we are limited in our ability to understand
by our ability to understand
RebelAAmericanOZen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 22 by jar, posted 09-01-2007 9:41 PM jar has replied

Replies to this message:
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jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 30 of 44 (419294)
09-01-2007 11:30 PM
Reply to: Message 29 by RAZD
09-01-2007 11:12 PM


Re: Ratites and neoteny
Correct. And from what I have been able to gather, all of them exhibit either flightless or minimal flight adaption.
I wish one of our more knowledgeable bio-paleo folk would drop in.
AbE: I have also been trying to follow up on the "Old Jaws" moniker, to see if that might be related.
Edited by jar, : No reason given.

Aslan is not a Tame Lion

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