It's become a widespread practice to look upon *Archaeopteryx* as a bird relativepowered by the front limbs only) either evolved at least twice, or was lost/modified in some deinonychosaurs.
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
Here is a paper that discusses this question in the process of describing phylogenetic methods
that put *Archaeopteryx* it "robustly" back into Avialae.
Other phylogenetic methods support the other practice, and readers are invited to compare them
and to draw their own conclusions.
"Likelihood reinstates *Archaeopteryx* as a primitive bird"
Michael S. Y. Lee and Trevor H. Worthy https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3297401/
Abstract:
The widespread view that Archaeopteryx was a primitive (basal) bird has been recently challenged by a comprehensive phylogenetic analysis that placed Archaeopteryx with deinonychosaurian theropods. The new phylogeny suggested that typical bird flight (
However, this parsimony-based result was acknowledged to be weakly supported. Maximum-likelihood and related Bayesian methods applied to the same dataset yield a different and more orthodox result: Archaeopteryx is restored as a basal bird withbootstrap frequency of 73 per cent and posterior probability of 1.
These results are consistent with a single origin of typical (forelimb-powered) bird flight. The Archaeopteryx–deinonychosaur clade retrieved by parsimony is supported by more characters (which are on average more homoplasious), whereas theArchaeopteryx–bird clade retrieved by likelihood-based methods is supported by fewer characters (but on average less homoplasious). Both positions for Archaeopteryx remain plausible, highlighting the hazy boundary between birds and advanced theropods.
I am unable to come to any decision about this due to lack of experience with these phylogenetic methods.
I hope our s.b.p. expert, John Harshman, can give us some insight on what to make of this paper.
The article is free access, but you may need to click on "FREE Full text" at the upper right
of the webpage I linked to see it.
Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
University of South Carolina
http://people.math.sc.edu/nyikos
It's become a widespread practice to look upon *Archaeopteryx* as a bird relativepowered by the front limbs only) either evolved at least twice, or was lost/modified in some deinonychosaurs.
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
Here is a paper that discusses this question in the process of describing phylogenetic methods
that put *Archaeopteryx* it "robustly" back into Avialae.
Other phylogenetic methods support the other practice, and readers are invited to compare them
and to draw their own conclusions.
"Likelihood reinstates *Archaeopteryx* as a primitive bird"
Michael S. Y. Lee and Trevor H. Worthy https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3297401/
Abstract:
The widespread view that Archaeopteryx was a primitive (basal) bird has been recently challenged by a comprehensive phylogenetic analysis that placed Archaeopteryx with deinonychosaurian theropods. The new phylogeny suggested that typical bird flight (
However, this parsimony-based result was acknowledged to be weakly supported. Maximum-likelihood and related Bayesian methods applied to the same dataset yield a different and more orthodox result: Archaeopteryx is restored as a basal bird withbootstrap frequency of 73 per cent and posterior probability of 1.
These results are consistent with a single origin of typical (forelimb-powered) bird flight. The Archaeopteryx–deinonychosaur clade retrieved by parsimony is supported by more characters (which are on average more homoplasious), whereas theArchaeopteryx–bird clade retrieved by likelihood-based methods is supported by fewer characters (but on average less homoplasious). Both positions for Archaeopteryx remain plausible, highlighting the hazy boundary between birds and advanced theropods.
I am unable to come to any decision about this due to lack of experience
with these phylogenetic methods.
I hope our s.b.p. expert, John Harshman, can give us some insight on what to make of this paper.
The article is free access, but you may need to click on "FREE Full text" at the upper right
of the webpage I linked to see it.
Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
University of South Carolina
http://people.math.sc.edu/nyikos
On Tuesday, November 29, 2022 at 7:55:04 AM UTC-8, peter2...@gmail.com wrote:powered by the front limbs only) either evolved at least twice, or was lost/modified in some deinonychosaurs.
It's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
Here is a paper that discusses this question in the process of describing phylogenetic methods
that put *Archaeopteryx* it "robustly" back into Avialae.
Other phylogenetic methods support the other practice, and readers are invited to compare them
and to draw their own conclusions.
"Likelihood reinstates *Archaeopteryx* as a primitive bird"
Michael S. Y. Lee and Trevor H. Worthy
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3297401/
Abstract:
The widespread view that Archaeopteryx was a primitive (basal) bird has been recently challenged by a comprehensive phylogenetic analysis that placed Archaeopteryx with deinonychosaurian theropods. The new phylogeny suggested that typical bird flight (
bootstrap frequency of 73 per cent and posterior probability of 1.
However, this parsimony-based result was acknowledged to be weakly supported. Maximum-likelihood and related Bayesian methods applied to the same dataset yield a different and more orthodox result: Archaeopteryx is restored as a basal bird with
Archaeopteryx–bird clade retrieved by likelihood-based methods is supported by fewer characters (but on average less homoplasious). Both positions for Archaeopteryx remain plausible, highlighting the hazy boundary between birds and advanced theropods.
These results are consistent with a single origin of typical (forelimb-powered) bird flight. The Archaeopteryx–deinonychosaur clade retrieved by parsimony is supported by more characters (which are on average more homoplasious), whereas the
inference can greatly overestimate support if the models implemented are inadequate [8,23]. Resolution of the precise position of Archaeopteryx will likely require more empirical data such as new fossils or novel characters."
I am unable to come to any decision about this due to lack of experience
with these phylogenetic methods.
I hope our s.b.p. expert, John Harshman, can give us some insight on what to make of this paper.
The article is free access, but you may need to click on "FREE Full text" at the upper right
of the webpage I linked to see it.
Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
University of South Carolina
http://people.math.sc.edu/nyikos
If you're unable to come to a decision, does that bother you? The authors are similarly diffident:
"The results here do not demonstrate unequivocally that Archaeopteryx belongs with birds rather than with deinonychosaurs; bootstrap support is only approximately 73 per cent, while the posterior probability of 1 is tempered by arguments that Bayesian
Despite your contempt for my recommendation of a fairly-easily read textbook on phylogenetic trees,
I still think your understanding would be augemented by it. (It goes beyond what you learned from Romer.)
On 11/29/22 8:36 AM, erik simpson wrote:flight (powered by the front limbs only) either evolved at least twice, or was lost/modified in some deinonychosaurs.
On Tuesday, November 29, 2022 at 7:55:04 AM UTC-8, peter2...@gmail.com wrote:
It's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
Here is a paper that discusses this question in the process of describing phylogenetic methods
that put *Archaeopteryx* it "robustly" back into Avialae.
Other phylogenetic methods support the other practice, and readers are invited to compare them
and to draw their own conclusions.
"Likelihood reinstates *Archaeopteryx* as a primitive bird"
Michael S. Y. Lee and Trevor H. Worthy
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3297401/
Abstract:
The widespread view that Archaeopteryx was a primitive (basal) bird has been recently challenged by a comprehensive phylogenetic analysis that placed Archaeopteryx with deinonychosaurian theropods. The new phylogeny suggested that typical bird
bootstrap frequency of 73 per cent and posterior probability of 1.
However, this parsimony-based result was acknowledged to be weakly supported. Maximum-likelihood and related Bayesian methods applied to the same dataset yield a different and more orthodox result: Archaeopteryx is restored as a basal bird with
Archaeopteryx–bird clade retrieved by likelihood-based methods is supported by fewer characters (but on average less homoplasious). Both positions for Archaeopteryx remain plausible, highlighting the hazy boundary between birds and advanced theropods.
These results are consistent with a single origin of typical (forelimb-powered) bird flight. The Archaeopteryx–deinonychosaur clade retrieved by parsimony is supported by more characters (which are on average more homoplasious), whereas the
Bayesian inference can greatly overestimate support if the models implemented are inadequate [8,23]. Resolution of the precise position of Archaeopteryx will likely require more empirical data such as new fossils or novel characters."
I am unable to come to any decision about this due to lack of experience >> with these phylogenetic methods.
I hope our s.b.p. expert, John Harshman, can give us some insight on what to make of this paper.
The article is free access, but you may need to click on "FREE Full text" at the upper right
of the webpage I linked to see it.
Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
University of South Carolina
http://people.math.sc.edu/nyikos
If you're unable to come to a decision, does that bother you? The authors are similarly diffident:
"The results here do not demonstrate unequivocally that Archaeopteryx belongs with birds rather than with deinonychosaurs; bootstrap support is only approximately 73 per cent, while the posterior probability of 1 is tempered by arguments that
Despite your contempt for my recommendation of a fairly-easily read textbook on phylogenetic trees,Are you referring to Tree Thinking?
I still think your understanding would be augemented by it. (It goes beyond what you learned from Romer.)
On 11/29/22 7:55 AM, Peter Nyikos wrote:
It's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
I will note that at least some specimens of Archaeopteryx have what look like
flight feathers on the rear legs, though less prominently so than in Microraptor.
As for whether Archaopteryx is a bird, isn't that a matter of personal
taste in definitions?
John, I'll think some more later about what you wrote about the technical aspects
of phylogenetic methods. For now I will focus on what I call the "down to earth"
implications in my second paragraph below.
On Tuesday, November 29, 2022 at 1:40:24 PM UTC-5, John Harshman wrote:
On 11/29/22 7:55 AM, Peter Nyikos wrote:
It's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
<snip to get to your words on this, John>
I will note that at least some specimens of Archaeopteryx have what look like
flight feathers on the rear legs, though less prominently so than in
Microraptor.
"flight feathers" indicates a very noticeable lack of symmetry, making these feathers
into miniature airfoils. AFAIK this need not indicate powered flight.
It would seem that they would be at least as good for gliding.
Would you agree, John?
I'd also like to hear from Daud Deden on this. We've talked a lot aboutused both the forelimbs and hindlimbs, and has been argued to be a glider [21] and asymmetric pennaceous feathers indicating aerodynamic ability are known only in dromaeosaurus outside of birds [22]."
the difference between gliding and powered flight in the last two months or so.
As for Microraptor, which all analyses by the authors place among the deinonychosaurs,
the linked article says:
"Powered, forewing-only flight typical of modern birds has been generally inferred to be present only in *Archaeopteryx* and other birds [2,5,20].The flight capabilities of some deinonychosaurs remain contentious: the most proficient, *Microraptor gui,*
Note the attribution of forewing-only flight to *Archaeopteryx* despite the feathers on the
legs that you mention, John. Those feathers might make substantial contributions to flight
just like the tail feathers (retrices) are known to do in present-day birds.
As for whether Archaopteryx is a bird, isn't that a matter of personal
taste in definitions?
To some extent, yes, but placing it in Avialae, as the Baysean and ML analyses do, would satisfy
a lot more personal tastes than relying on flight remiges to define it as one.
The rest of the paragraph I quoted takes us back to more technical aspects of the analyses, but it also weaves it in with more talk about powered flight.Wellnhoferia, and in ‘true’ birds), or an earlier origin at the base of Paraves (with subsequent reduced flying ability or modifications to four-winged locomotion in various deinonychosaurs; [17,21])."
"The likelihood-based phylogenies are consistent with a single origin of typical forewing-driven flight with no losses in basal birds (i.e. the taxa here sampled); in contrast, the parsimony tree implies either minimally two origins (in Archaeopteryx/
On 11/30/22 10:25 AM, Peter Nyikos wrote:
John, I'll think some more later about what you wrote about the technical aspects
of phylogenetic methods. For now I will focus on what I call the "down to earth"
implications in my second paragraph below.
On Tuesday, November 29, 2022 at 1:40:24 PM UTC-5, John Harshman wrote:
On 11/29/22 7:55 AM, Peter Nyikos wrote:
It's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
<snip to get to your words on this, John>
I will note that at least some specimens of Archaeopteryx have what look like
flight feathers on the rear legs, though less prominently so than in
Microraptor.
"flight feathers" indicates a very noticeable lack of symmetry, making these feathersYes, though it seems clear that Archaeopteryx was flying, though I would
into miniature airfoils. AFAIK this need not indicate powered flight.
It would seem that they would be at least as good for gliding.
Would you agree, John?
not suppose that he was flapping his legs.
I'd also like to hear from Daud Deden on this. We've talked a lot about the difference between gliding and powered flight in the last two months or so.
gui,* used both the forelimbs and hindlimbs, and has been argued to be a glider [21] and asymmetric pennaceous feathers indicating aerodynamic ability are known only in dromaeosaurus outside of birds [22]."As for Microraptor, which all analyses by the authors place among the deinonychosaurs,
the linked article says:
"Powered, forewing-only flight typical of modern birds has been generally inferred to be present only in *Archaeopteryx* and other birds [2,5,20].The flight capabilities of some deinonychosaurs remain contentious: the most proficient, *Microraptor
Note the attribution of forewing-only flight to *Archaeopteryx* despite the feathers on theThat seems most likely. Lift only, not thrust.
legs that you mention, John. Those feathers might make substantial contributions to flight
just like the tail feathers (retrices) are known to do in present-day birds.
As for whether Archaopteryx is a bird, isn't that a matter of personal
taste in definitions?
To some extent, yes, but placing it in Avialae, as the Baysean and ML analyses do, would satisfy
a lot more personal tastes than relying on flight remiges to define it as one.
Wellnhoferia, and in ‘true’ birds), or an earlier origin at the base of Paraves (with subsequent reduced flying ability or modifications to four-winged locomotion in various deinonychosaurs; [17,21])."The rest of the paragraph I quoted takes us back to more technical aspects of
the analyses, but it also weaves it in with more talk about powered flight.
"The likelihood-based phylogenies are consistent with a single origin of typical forewing-driven flight with no losses in basal birds (i.e. the taxa here sampled); in contrast, the parsimony tree implies either minimally two origins (in Archaeopteryx/
I don't think we can reliably distinguish the difference with current data.
On Wednesday, November 30, 2022 at 3:14:30 PM UTC-5, John Harshman wrote:
On 11/30/22 10:25 AM, Peter Nyikos wrote:
John, I'll think some more later about what you wrote about the technical aspects
of phylogenetic methods. For now I will focus on what I call the "down to earth"
implications in my second paragraph below.
On Tuesday, November 29, 2022 at 1:40:24 PM UTC-5, John Harshman wrote:
On 11/29/22 7:55 AM, Peter Nyikos wrote:
It's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
<snip to get to your words on this, John>
I will note that at least some specimens of Archaeopteryx have what look like
flight feathers on the rear legs, though less prominently so than in
Microraptor.
"flight feathers" indicates a very noticeable lack of symmetry, making these feathersYes, though it seems clear that Archaeopteryx was flying, though I would not suppose that he was flapping his legs.
into miniature airfoils. AFAIK this need not indicate powered flight.
It would seem that they would be at least as good for gliding.
Would you agree, John?
I'd also like to hear from Daud Deden on this. We've talked a lot about the difference between gliding and powered flight in the last two months or so.
https://www.bbc.com/news/science-environment-43386262
It's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
Per picture, asymmetrical feathers on the rear legs would add both to (pheasant-like) gliding length and to uplift during whole body flapping, if broad bony tail and rear legs were united during forewing strokes.flight from trees imo.
I watched a duck with injured legs try to lift off, it couldn't push down against earth so it couldn't launch upwards.
The short widespread tailfan of modern birds differs from archaics with long bony tails, the liftoff must have been different. Archy had clawed wings so it could climb trees, had weak wings, had heavy jaws counterbalanced by bony tail, indicating
gui,* used both the forelimbs and hindlimbs, and has been argued to be a glider [21] and asymmetric pennaceous feathers indicating aerodynamic ability are known only in dromaeosaurus outside of birds [22]."As for Microraptor, which all analyses by the authors place among the deinonychosaurs,
the linked article says:
"Powered, forewing-only flight typical of modern birds has been generally inferred to be present only in *Archaeopteryx* and other birds [2,5,20].The flight capabilities of some deinonychosaurs remain contentious: the most proficient, *Microraptor
Note the attribution of forewing-only flight to *Archaeopteryx* despite the feathers on the
legs that you mention, John. Those feathers might make substantial contributions to flight
just like the tail feathers (retrices) are known to do in present-day birds.
That seems most likely. Lift only, not thrust.
Archaeopteryx/Wellnhoferia, and in ‘true’ birds), or an earlier origin at the base of Paraves (with subsequent reduced flying ability or modifications to four-winged locomotion in various deinonychosaurs; [17,21])."The rest of the paragraph I quoted takes us back to more technical aspects of
the analyses, but it also weaves it in with more talk about powered flight.
"The likelihood-based phylogenies are consistent with a single origin of typical forewing-driven flight with no losses in basal birds (i.e. the taxa here sampled); in contrast, the parsimony tree implies either minimally two origins (in
Despite your contempt for my recommendation of a fairly-easily read textbook on phylogenetic trees,
I still think your understanding would be augemented by it. (It goes beyond what you learned from Romer.)
On 11/29/22 11:36, erik simpson wrote:
Despite your contempt for my recommendation of a fairly-easily read textbook on phylogenetic trees,
I still think your understanding would be augemented by it. (It goes beyond what you learned from Romer.)
what text is that?
On Wednesday, November 30, 2022 at 9:56:12 PM UTC-5, daud....@gmail.com wrote:
On Wednesday, November 30, 2022 at 3:14:30 PM UTC-5, John Harshman wrote:
On 11/30/22 10:25 AM, Peter Nyikos wrote:
John, I'll think some more later about what you wrote about the technical aspects
of phylogenetic methods. For now I will focus on what I call the "down to earth"
implications in my second paragraph below.
On Tuesday, November 29, 2022 at 1:40:24 PM UTC-5, John Harshman wrote:
On 11/29/22 7:55 AM, Peter Nyikos wrote:
It's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
<snip to get to your words on this, John>
I will note that at least some specimens of Archaeopteryx have what look like
flight feathers on the rear legs, though less prominently so than in >> Microraptor.
Daud, it's amazing how you keep coming up with links that are right on-topic."flight feathers" indicates a very noticeable lack of symmetry, making these feathersYes, though it seems clear that Archaeopteryx was flying, though I would not suppose that he was flapping his legs.
into miniature airfoils. AFAIK this need not indicate powered flight. It would seem that they would be at least as good for gliding.
Would you agree, John?
I'd also like to hear from Daud Deden on this. We've talked a lot about
the difference between gliding and powered flight in the last two months or so.
https://www.bbc.com/news/science-environment-43386262
Here is one on-topic aspect that you may have overlooked:
"Despite once being thought of as the first bird, experts now view the animal as a flying dinosaur."
Notice how well it goes with my introductory words to this whole thread: [repeated from top]flight from trees imo.
A red flag goes up whenever I see the word "experts." We mathematicians hardly ever use the wordIt's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
when talking about fellow mathematicians. We use expressions like "world-class researcher"
or "great lecturer". We are experts in our little specialties, but we don't use the word even there.
The highest praise is, "If anyone knows the answer to this problem, the first person to ask is _______"
That said, the line I quoted does give a big indication of which way the wind
is blowing. I've asked Trevor Worthy, with whom I corresponded several years ago,
what kind of reception his joint paper has received in the years since the paper
appeared in 2011. No answer yet, but here is the information on that paper again:
"Likelihood reinstates *Archaeopteryx* as a primitive bird"
Michael S. Y. Lee and Trevor H. Worthya https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3297401/
Per picture, asymmetrical feathers on the rear legs would add both to (pheasant-like) gliding length and to uplift during whole body flapping, if broad bony tail and rear legs were united during forewing strokes.
I watched a duck with injured legs try to lift off, it couldn't push down against earth so it couldn't launch upwards.
The short widespread tailfan of modern birds differs from archaics with long bony tails, the liftoff must have been different. Archy had clawed wings so it could climb trees, had weak wings, had heavy jaws counterbalanced by bony tail, indicating
My main comment this morning has to do with Microraptor, though it might also apply to "Archie."Microraptor gui,* used both the forelimbs and hindlimbs, and has been argued to be a glider [21] and asymmetric pennaceous feathers indicating aerodynamic ability are known only in dromaeosaurus outside of birds [22]."
As for Microraptor, which all analyses by the authors place among the deinonychosaurs,
the linked article says:
"Powered, forewing-only flight typical of modern birds has been generally inferred to be present only in *Archaeopteryx* and other birds [2,5,20].The flight capabilities of some deinonychosaurs remain contentious: the most proficient, *
But might it have been more than a glider? My initial impression was that leg-flapping
was impractical, but now I am having second thoughts.
The fastest swimming stroke is the American crawl, AFAIK. It involves a flutter kick,
beating the legs almost stiff-legged in short alternate strokes that move up and down.
Might Microraptor have used a variation on it for getting fast through the air?
It's also used in the only backstroke I've ever seen in competitive swimming,
except for underwater starts, which use a dolphin kick. The dolphin kick moves the legs simultaneously, and it is the only kick that is allowed
these days in the butterfly. [IIRC it's illegal to use the older frog kick.]
Note the attribution of forewing-only flight to *Archaeopteryx* despite the feathers on the
legs that you mention, John. Those feathers might make substantial contributions to flight
just like the tail feathers (retrices) are known to do in present-day birds.
I agreed with John on this one at first, but the comparison with swimming made me wonder.That seems most likely. Lift only, not thrust.
<snip for focus>Archaeopteryx/Wellnhoferia, and in ‘true’ birds), or an earlier origin at the base of Paraves (with subsequent reduced flying ability or modifications to four-winged locomotion in various deinonychosaurs; [17,21])."
The rest of the paragraph I quoted takes us back to more technical aspects of
the analyses, but it also weaves it in with more talk about powered flight.
"The likelihood-based phylogenies are consistent with a single origin of typical forewing-driven flight with no losses in basal birds (i.e. the taxa here sampled); in contrast, the parsimony tree implies either minimally two origins (in
I'll have to ask Trevor Worthy what he had in mind with that word "locomotion."
Was it just a help to providing lift, or did he think about swimming
along the same lines that I did just now?
Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
University of South Carolina
http://people.math.sc.edu/nyikos
PS I never could get good at the flutter kick; the frog kick takes me forward a lot faster
when I use only my legs to propel myself. Evidently there are fine points to it that
my body never picked up.
On 11/30/22 10:25 AM, Peter Nyikos wrote:
John, I'll think some more later about what you wrote about the technical aspects
of phylogenetic methods. For now I will focus on what I call the "down to earth"
implications in my second paragraph below.
On Tuesday, November 29, 2022 at 1:40:24 PM UTC-5, John Harshman wrote:
On 11/29/22 7:55 AM, Peter Nyikos wrote:
It's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
<snip to get to your words on this, John>
I will note that at least some specimens of Archaeopteryx have what look like
flight feathers on the rear legs, though less prominently so than in
Microraptor.
"flight feathers" indicates a very noticeable lack of symmetry, making these feathersYes, though it seems clear that Archaeopteryx was flying, though I would
into miniature airfoils. AFAIK this need not indicate powered flight.
It would seem that they would be at least as good for gliding.
Would you agree, John?
not suppose that he was flapping his legs.
gui,* used both the forelimbs and hindlimbs, and has been argued to be a glider [21] and asymmetric pennaceous feathers indicating aerodynamic ability are known only in dromaeosaurus outside of birds [22]."As for Microraptor, which all analyses by the authors place among the deinonychosaurs,
the linked article says:
"Powered, forewing-only flight typical of modern birds has been generally inferred to be present only in *Archaeopteryx* and other birds [2,5,20].The flight capabilities of some deinonychosaurs remain contentious: the most proficient, *Microraptor
Note the attribution of forewing-only flight to *Archaeopteryx* despite the feathers on the
legs that you mention, John. Those feathers might make substantial contributions to flight
just like the tail feathers (retrices) are known to do in present-day birds.
That seems most likely. Lift only, not thrust.
As for whether Archaopteryx is a bird, isn't that a matter of personal
taste in definitions?
To some extent, yes, but placing it in Avialae, as the Baysean and ML analyses do, would satisfy
a lot more personal tastes than relying on flight remiges to define it as one.
Wellnhoferia, and in ‘true’ birds), or an earlier origin at the base of Paraves (with subsequent reduced flying ability or modifications to four-winged locomotion in various deinonychosaurs; [17,21])."The rest of the paragraph I quoted takes us back to more technical aspects of
the analyses, but it also weaves it in with more talk about powered flight.
"The likelihood-based phylogenies are consistent with a single origin of typical forewing-driven flight with no losses in basal birds (i.e. the taxa here sampled); in contrast, the parsimony tree implies either minimally two origins (in Archaeopteryx/
I don't think we can reliably distinguish the difference with current data.
On Wednesday, November 30, 2022 at 3:14:30 PM UTC-5, John Harshman wrote:
On 11/30/22 10:25 AM, Peter Nyikos wrote:
John, I'll think some more later about what you wrote about the technical aspectsYes, though it seems clear that Archaeopteryx was flying, though I would
of phylogenetic methods. For now I will focus on what I call the "down to earth"
implications in my second paragraph below.
On Tuesday, November 29, 2022 at 1:40:24 PM UTC-5, John Harshman wrote: >>>> On 11/29/22 7:55 AM, Peter Nyikos wrote:
It's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
<snip to get to your words on this, John>
I will note that at least some specimens of Archaeopteryx have what look like
flight feathers on the rear legs, though less prominently so than in
Microraptor.
"flight feathers" indicates a very noticeable lack of symmetry, making these feathers
into miniature airfoils. AFAIK this need not indicate powered flight.
It would seem that they would be at least as good for gliding.
Would you agree, John?
not suppose that he was flapping his legs.
That was and still is my impression, but I am having second thoughts about this
also being true of Microraptor.
The fastest swimming stroke is the American crawl, AFAIK, although the Australian crawl
may be better for some. Both involve a flutter kick,
beating the legs almost stiff-legged in short alternate strokes that move up and down.
Might *Microraptor* have used a variation on it for getting fast through the air?
It's also used in the only backstroke I've ever seen in competitive swimming, except for underwater starts, which use a dolphin kick. The dolphin kick moves the legs simultaneously, and it is the only kick that is allowed
these days in swimming competitions where the butterfly is called for.
[IIRC it's illegal to use the older frog kick in swimming competition.]
So this is another possible way *Microraptor* might have flapped its legs, although "flapped" might not be the best word to use here.
What do you think of this idea, John? I don't know why what
works so well in water would not work in air, with the proper "equipment."
gui,* used both the forelimbs and hindlimbs, and has been argued to be a glider [21] and asymmetric pennaceous feathers indicating aerodynamic ability are known only in dromaeosaurus outside of birds [22]."As for Microraptor, which all analyses by the authors place among the deinonychosaurs,
the linked article says:
"Powered, forewing-only flight typical of modern birds has been generally inferred to be present only in *Archaeopteryx* and other birds [2,5,20].The flight capabilities of some deinonychosaurs remain contentious: the most proficient, *Microraptor
Note the attribution of forewing-only flight to *Archaeopteryx* despite the feathers on the
legs that you mention, John. Those feathers might make substantial contributions to flight
just like the tail feathers (retrices) are known to do in present-day birds.
That seems most likely. Lift only, not thrust.
I'm still inclined to think this, but I'd like to see your reaction to what I wrote about *Microraptor*.
One would think that what works so well in water might also work in air, with the proper "equipment."
Wellnhoferia, and in ‘true’ birds), or an earlier origin at the base of Paraves (with subsequent reduced flying ability or modifications to four-winged locomotion in various deinonychosaurs; [17,21])."As for whether Archaopteryx is a bird, isn't that a matter of personal >>>> taste in definitions?
To some extent, yes, but placing it in Avialae, as the Baysean and ML analyses do, would satisfy
a lot more personal tastes than relying on flight remiges to define it as one.
The rest of the paragraph I quoted takes us back to more technical aspects of
the analyses, but it also weaves it in with more talk about powered flight. >>>
"The likelihood-based phylogenies are consistent with a single origin of typical forewing-driven flight with no losses in basal birds (i.e. the taxa here sampled); in contrast, the parsimony tree implies either minimally two origins (in Archaeopteryx/
I don't think we can reliably distinguish the difference with current data.
I suppose you are talking about phylogeny here, not the details of flight.
On Wednesday, November 30, 2022 at 3:14:30 PM UTC-5, John Harshman wrote:
On 11/30/22 10:25 AM, Peter Nyikos wrote:
John, I'll think some more later about what you wrote about the technical aspects
of phylogenetic methods. For now I will focus on what I call the "down to earth"
implications in my second paragraph below.
On Tuesday, November 29, 2022 at 1:40:24 PM UTC-5, John Harshman wrote:
On 11/29/22 7:55 AM, Peter Nyikos wrote:
It's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
<snip to get to your words on this, John>
gui,* used both the forelimbs and hindlimbs, and has been argued to be a glider [21] and asymmetric pennaceous feathers indicating aerodynamic ability are known only in dromaeosaurus outside of birds [22]."I will note that at least some specimens of Archaeopteryx have what look like
flight feathers on the rear legs, though less prominently so than in
Microraptor.
That was and still is my impression, but I am having second thoughts about this"flight feathers" indicates a very noticeable lack of symmetry, making these feathersYes, though it seems clear that Archaeopteryx was flying, though I would not suppose that he was flapping his legs.
into miniature airfoils. AFAIK this need not indicate powered flight.
It would seem that they would be at least as good for gliding.
Would you agree, John?
also being true of Microraptor.
The fastest swimming stroke is the American crawl, AFAIK, although the Australian crawl
may be better for some. Both involve a flutter kick,
beating the legs almost stiff-legged in short alternate strokes that move up and down.
Might *Microraptor* have used a variation on it for getting fast through the air?
It's also used in the only backstroke I've ever seen in competitive swimming,
except for underwater starts, which use a dolphin kick. The dolphin kick moves the legs simultaneously, and it is the only kick that is allowed
these days in swimming competitions where the butterfly is called for.
[IIRC it's illegal to use the older frog kick in swimming competition.]
So this is another possible way *Microraptor* might have flapped its legs, although "flapped" might not be the best word to use here.
What do you think of this idea, John? I don't know why what
works so well in water would not work in air, with the proper "equipment."
<snip for focus>
As for Microraptor, which all analyses by the authors place among the deinonychosaurs,
the linked article says:
"Powered, forewing-only flight typical of modern birds has been generally inferred to be present only in *Archaeopteryx* and other birds [2,5,20].The flight capabilities of some deinonychosaurs remain contentious: the most proficient, *Microraptor
Note the attribution of forewing-only flight to *Archaeopteryx* despite the feathers on the
legs that you mention, John. Those feathers might make substantial contributions to flight
just like the tail feathers (retrices) are known to do in present-day birds.
That seems most likely. Lift only, not thrust.I'm still inclined to think this, but I'd like to see your reaction to what I wrote about *Microraptor*.
One would think that what works so well in water might also work in air, with the proper "equipment."
As for whether Archaopteryx is a bird, isn't that a matter of personal >> taste in definitions?
To some extent, yes, but placing it in Avialae, as the Baysean and ML analyses do, would satisfy
a lot more personal tastes than relying on flight remiges to define it as one.
Archaeopteryx/Wellnhoferia, and in ‘true’ birds), or an earlier origin at the base of Paraves (with subsequent reduced flying ability or modifications to four-winged locomotion in various deinonychosaurs; [17,21])."The rest of the paragraph I quoted takes us back to more technical aspects of
the analyses, but it also weaves it in with more talk about powered flight.
"The likelihood-based phylogenies are consistent with a single origin of typical forewing-driven flight with no losses in basal birds (i.e. the taxa here sampled); in contrast, the parsimony tree implies either minimally two origins (in
I don't think we can reliably distinguish the difference with current data.I suppose you are talking about phylogeny here, not the details of flight. Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
Univ. of South Carolina in Columbia
http://people.math.sc.edu/nyikos
On Thursday, December 8, 2022 at 4:15:03 PM UTC-8, peter2...@gmail.com wrote:
On Wednesday, November 30, 2022 at 3:14:30 PM UTC-5, John Harshman wrote:
On 11/30/22 10:25 AM, Peter Nyikos wrote:
John, I'll think some more later about what you wrote about the technical aspects
of phylogenetic methods. For now I will focus on what I call the "down to earth"
implications in my second paragraph below.
On Tuesday, November 29, 2022 at 1:40:24 PM UTC-5, John Harshman wrote:
On 11/29/22 7:55 AM, Peter Nyikos wrote:
It's become a widespread practice to look upon *Archaeopteryx* as a bird relative
rather than an actual bird (member of Avialae). This practice puts it among the deinonychosaurs.
This seemingly technical question has down to earth implications: did flight among birds
go through a four-winged phase, or did birds always rely on two-winged powered flight?
<snip to get to your words on this, John>
Microraptor gui,* used both the forelimbs and hindlimbs, and has been argued to be a glider [21] and asymmetric pennaceous feathers indicating aerodynamic ability are known only in dromaeosaurus outside of birds [22]."I will note that at least some specimens of Archaeopteryx have what look like
flight feathers on the rear legs, though less prominently so than in >> Microraptor.
That was and still is my impression, but I am having second thoughts about this"flight feathers" indicates a very noticeable lack of symmetry, making these feathersYes, though it seems clear that Archaeopteryx was flying, though I would not suppose that he was flapping his legs.
into miniature airfoils. AFAIK this need not indicate powered flight. It would seem that they would be at least as good for gliding.
Would you agree, John?
also being true of Microraptor.
The fastest swimming stroke is the American crawl, AFAIK, although the Australian crawl
may be better for some. Both involve a flutter kick,
beating the legs almost stiff-legged in short alternate strokes that move up and down.
Might *Microraptor* have used a variation on it for getting fast through the air?
It's also used in the only backstroke I've ever seen in competitive swimming,
except for underwater starts, which use a dolphin kick. The dolphin kick moves the legs simultaneously, and it is the only kick that is allowed these days in swimming competitions where the butterfly is called for. [IIRC it's illegal to use the older frog kick in swimming competition.]
So this is another possible way *Microraptor* might have flapped its legs, although "flapped" might not be the best word to use here.
What do you think of this idea, John? I don't know why what
works so well in water would not work in air, with the proper "equipment."
<snip for focus>
As for Microraptor, which all analyses by the authors place among the deinonychosaurs,
the linked article says:
"Powered, forewing-only flight typical of modern birds has been generally inferred to be present only in *Archaeopteryx* and other birds [2,5,20].The flight capabilities of some deinonychosaurs remain contentious: the most proficient, *
Note the attribution of forewing-only flight to *Archaeopteryx* despite the feathers on the
legs that you mention, John. Those feathers might make substantial contributions to flight
just like the tail feathers (retrices) are known to do in present-day birds.
That seems most likely. Lift only, not thrust.I'm still inclined to think this, but I'd like to see your reaction to what I wrote about *Microraptor*.
One would think that what works so well in water might also work in air, with the proper "equipment."
As for whether Archaopteryx is a bird, isn't that a matter of personal
taste in definitions?
To some extent, yes, but placing it in Avialae, as the Baysean and ML analyses do, would satisfy
a lot more personal tastes than relying on flight remiges to define it as one.
Archaeopteryx/Wellnhoferia, and in ‘true’ birds), or an earlier origin at the base of Paraves (with subsequent reduced flying ability or modifications to four-winged locomotion in various deinonychosaurs; [17,21])."The rest of the paragraph I quoted takes us back to more technical aspects of
the analyses, but it also weaves it in with more talk about powered flight.
"The likelihood-based phylogenies are consistent with a single origin of typical forewing-driven flight with no losses in basal birds (i.e. the taxa here sampled); in contrast, the parsimony tree implies either minimally two origins (in
I don't think we can reliably distinguish the difference with current data.I suppose you are talking about phylogeny here, not the details of flight. Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
Univ. of South Carolina in Columbia
http://people.math.sc.edu/nyikos
Water and air have many differences; a similar remark holds for swimming and flight.
You might check https://en.wikipedia.org/wiki/Tradeoffs_for_locomotion_in_air_and_water
- Capt. Obvious
On 11/29/22 11:36, erik simpson wrote:
Despite your contempt for my recommendation of a fairly-easily read textbook on phylogenetic trees,what text is that?
I still think your understanding would be augemented by it.
(It goes beyond what you learned from Romer.)
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