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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: |
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, : ... 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.
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jar Member (Idle past 394 days) Posts: 34026 From: Texas!! Joined: |
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 |
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RAZD Member (Idle past 1405 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Nice article, but hard to look at those hand\wing bones ...
What do we have for Ratitae or Palaeognathae fossils? Thanks 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.
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molbiogirl Member (Idle past 2641 days) Posts: 1909 From: MO Joined: |
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 CharactersAnna 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: |
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: |
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 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.
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jar Member (Idle past 394 days) Posts: 34026 From: Texas!! Joined: |
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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Rob  Suspended Member (Idle past 5848 days) Posts: 2297 Joined: |
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: |
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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Rob  Suspended Member (Idle past 5848 days) Posts: 2297 Joined: |
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: |
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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molbiogirl Member (Idle past 2641 days) Posts: 1909 From: MO Joined: |
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: |
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: |
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: All the other (living) birds are in the other superorder. Interesting. 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.
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jar Member (Idle past 394 days) Posts: 34026 From: Texas!! Joined: |
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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