Possibly interesting. The authors state a preference for observation of
captive
primates as a control. The data was collected by sending a survey to primate
caregivers at zoos. They conlcude "These lines of evidence tentatively
indicate
that humans and hylobatids reflect the ancestral body form with respect to
lumbar mobility and positional behavior." Do note that the genetic evidence
places hylobatids further from humans than chimpanzees...

<https://www.cambridge.org/core/journals/evolutionary-human-sciences/article/bipedal-locomotion-in-zoo-apes-revisiting-the-hylobatian-model-for-bipedal-origins/C1DC53BDC1F75F0627B9504A26388E72>

Abstract
Bipedal locomotion is a hallmark of being human. Yet, the body form from
which
bipedalism evolved remains unclear. Specifically, the positional behavior
(i.e.,
orthograde vs. pronograde) and the length of the lumbar spine (i.e., long
and mobile
vs. short and stiff) of the last common ancestor (LCA) of the African
great apes and
humans require further investigation. While fossil evidence would be the most
conclusive, the paucity of hominid fossils from 5-10 million years ago
makes this
field of research challenging. In their absence, extant primate anatomy
and behavior
may offer some insight into the ancestral body form from which bipedalism
could
most easily evolve. Here, we quantify the frequency of bipedalism in a
large sample
(N=496) of zoo-housed hominoids and cercopithecines. Our results show that
while
each studied species of ape and monkey can move bipedally, hylobatids are
significantly more bipedal and engage in bipedal locomotion more
frequently and
for greater distances than any other primate sampled. These data support
hypotheses of an orthograde, long-backed, and arboreal LCA, which is
consistent
with hominoid fossils from the middle-to-late Miocene. If true,
knuckle-walking
evolved in parallel in Pan and Gorilla, and the human body form,
particularly the
long lower back and orthograde posture, is conserved.

"The only animals in our sample with a combination of an orthograde body
posture and
a long lumbar region of the spine are hylobatids and, thus, high
frequencies of bipedal
locomotion in these lesser apes would align with aspects of the hylobatian
model."

"Here, we investigate the frequency of bipedalism in a large sample of
zoo-housed
primates. We posit that collecting these data on captive primates is
preferable to wild
observations for addressing our particular question given the different
forest structures
of the African and Asian rainforests, and, in this way, zoo data may serve
as a “control”
for ecological differences and allow us to focus specifically on
anatomical predispositions
for bipedal locomotion."

On Friday 18 March 2022 at 17:57:24 UTC, Primum Sapienti wrote:

Possibly interesting. The authors state a
preference for observation of captive primates
as a control. The data was collected by
sending a survey to primate caregivers at zoos.
They conlcude "These lines of evidence
tentatively indicate that humans and
hylobatids reflect the ancestral body form
with respect to lumbar mobility and positional
behavior." Do note that the genetic evidence
places hylobatids further from humans than
chimpanzees...

<https://www.cambridge.org/core/journals/evolutionary-human-sciences/article/bipedal-locomotion-in-zoo-apes-revisiting-the-hylobatian-model-for-bipedal-origins/C1DC53BDC1F75F0627B9504A26388E72>

Abstract
Bipedal locomotion is a hallmark of being human.
Yet, the body form from which bipedalism evolved
remains unclear. Specifically, the positional
behavior (i.e., orthograde vs. pronograde) and the
length of the lumbar spine (i.e., long and mobile
vs. short and stiff) of the last common ancestor
(LCA) of the African great apes and humans
require further investigation. While fossil evidence
would be the most conclusive, the paucity of
hominid fossils from 5-10 million years ago makes
this field of research challenging. In their absence,
extant primate anatomy and behavior may offer
some insight into the ancestral body form from
which bipedalism could most easily evolve. Here,
we quantify the frequency of bipedalism in a large
sample (N=496) of zoo-housed hominoids and
cercopithecines. Our results show that while each
studied species of ape and monkey can move
bipedally, hylobatids are significantly more
bipedal and engage in bipedal locomotion more
frequently and for greater distances than any
other primate sampled. These data support
hypotheses of an orthograde, long-backed, and
arboreal LCA, which is consistent with hominoid
fossils from the middle-to-late Miocene. If true,
knuckle-walking evolved in parallel in Pan and
Gorilla, and the human body form, particularly
the long lower back and orthograde posture, is
conserved.

"The only animals in our sample with a
combination of an orthograde body posture and a
long lumbar region of the spine are hylobatids
and, thus, high frequencies of bipedal locomotion
in these lesser apes would align with aspects of
the hylobatian model."

"Here, we investigate the frequency of bipedalism
in a large sample of zoo-housed primates. We
posit that collecting these data on captive
primates is preferable to wild observations for
addressing our particular question given the
different forest structures of the African and Asian
rainforests, and, in this way, zoo data may serve
as a “control” for ecological differences and allow
us to focus specifically on anatomical
predispositions for bipedal locomotion."

:-D
Finally, some PAs are admitting (our TREE article) that
- early apes were already vertical, google "aquarboreal",
- KWing evolved in Pan // Gorilla.

> <https://www.cambridge.org/core/journals/evolutionary-human-sciences/article/bipedal-locomotion-in-zoo-apes-revisiting-the-hylobatian-model-for-bipedal-origins/C1DC53BDC1F75F0627B9504A26388E72>
>
> Abstract
> Bipedal locomotion is a hallmark of being human.
> Yet, the body form from which bipedalism evolved
> remains unclear. Specifically, the positional
> behavior (i.e., orthograde vs. pronograde) and the
> length of the lumbar spine (i.e., long and mobile
> vs. short and stiff) of the last common ancestor
> (LCA) of the African great apes and humans
> require further investigation. While fossil evidence
> would be the most conclusive, the paucity of
> hominid fossils from 5-10 million years ago makes
> this field of research challenging. In their absence,
> extant primate anatomy and behavior may offer
> some insight into the ancestral body form from
> which bipedalism could most easily evolve. Here,
> we quantify the frequency of bipedalism in a large
> sample (N=496) of zoo-housed hominoids and
> cercopithecines. Our results show that while each
> studied species of ape and monkey can move
> bipedally, hylobatids are significantly more
> bipedal and engage in bipedal locomotion more
> frequently and for greater distances than any
> other primate sampled. These data support
> hypotheses of an orthograde, long-backed, and
> arboreal LCA, which is consistent with hominoid
> fossils from the middle-to-late Miocene. If true,
> knuckle-walking evolved in parallel in Pan and
> Gorilla, and the human body form, particularly
> the long lower back and orthograde posture, is
> conserved.
>
> "The only animals in our sample with a
> combination of an orthograde body posture and a
> long lumbar region of the spine are hylobatids
> and, thus, high frequencies of bipedal locomotion
> in these lesser apes would align with aspects of
> the hylobatian model."
>
> "Here, we investigate the frequency of bipedalism
> in a large sample of zoo-housed primates. We
> posit that collecting these data on captive
> primates is preferable to wild observations for
> addressing our particular question given the
> different forest structures of the African and Asian
> rainforests, and, in this way, zoo data may serve
> as a “control” for ecological differences and allow
> us to focus specifically on anatomical
> predispositions for bipedal locomotion."

On Friday, March 18, 2022 at 1:57:24 PM UTC-4, Primum Sapienti wrote:
> Possibly interesting. The authors state a preference for observation of
> captive
> primates as a control. The data was collected by sending a survey to primate
> caregivers at zoos. They conlcude "These lines of evidence tentatively
> indicate
> that humans and hylobatids reflect the ancestral body form with respect to
> lumbar mobility and positional behavior." Do note that the genetic evidence
> places hylobatids further from humans than chimpanzees...
>
> <https://www.cambridge.org/core/journals/evolutionary-human-sciences/article/bipedal-locomotion-in-zoo-apes-revisiting-the-hylobatian-model-for-bipedal-origins/C1DC53BDC1F75F0627B9504A26388E72>
>
> Abstract
> Bipedal locomotion is a hallmark of being human. Yet, the body form from
> which
> bipedalism evolved remains unclear. Specifically, the positional behavior
> (i.e.,
> orthograde vs. pronograde) and the length of the lumbar spine (i.e., long
> and mobile
> vs. short and stiff) of the last common ancestor (LCA) of the African
> great apes and
> humans require further investigation. While fossil evidence would be the most
> conclusive, the paucity of hominid fossils from 5-10 million years ago
> makes this
> field of research challenging. In their absence, extant primate anatomy
> and behavior
> may offer some insight into the ancestral body form from which bipedalism
> could
> most easily evolve. Here, we quantify the frequency of bipedalism in a
> large sample
> (N=496) of zoo-housed hominoids and cercopithecines. Our results show that
> while
> each studied species of ape and monkey can move bipedally, hylobatids are
> significantly more bipedal and engage in bipedal locomotion more
> frequently and
> for greater distances than any other primate sampled. These data support
> hypotheses of an orthograde, long-backed, and arboreal LCA, which is
> consistent
> with hominoid fossils from the middle-to-late Miocene. If true,
> knuckle-walking
> evolved in parallel in Pan and Gorilla, and the human body form,
> particularly the
> long lower back and orthograde posture, is conserved.
>
> "The only animals in our sample with a combination of an orthograde body
> posture and
> a long lumbar region of the spine are hylobatids and, thus, high
> frequencies of bipedal
> locomotion in these lesser apes would align with aspects of the hylobatian
> model."
>
> "Here, we investigate the frequency of bipedalism in a large sample of
> zoo-housed
> primates. We posit that collecting these data on captive primates is
> preferable to wild
> observations for addressing our particular question given the different
> forest structures
> of the African and Asian rainforests, and, in this way, zoo data may serve
> as a “control”
> for ecological differences and allow us to focus specifically on
> anatomical predispositions
> for bipedal locomotion."

Quasi-hylobatid: ancestor of modern siamangs, gibbons & humans (all remain orthogonal bipeds) and arboreal-bowl-nesting great apes with short legs & short back with mixed quadrupedal/bipedal locomotion.

On Friday 18 March 2022 at 17:57:24 UTC, Primum Sapienti wrote:

> They conlcude "These lines of evidence
> tentatively indicate that humans and
> hylobatids reflect the ancestral body form
> with respect to lumbar mobility and positional
> behavior." Do note that the genetic evidence
> places hylobatids further from humans than
> chimpanzees...

Hylobatids are the ancestors of all apes.
The coding for hylobatid body form is
in the genes of those apes, to which
they can revert when necessary.

<https://www.cambridge.org/core/journals/evolutionary-human-sciences/article/bipedal-locomotion-in-zoo-apes-revisiting-the-hylobatian-model-for-bipedal-origins/C1DC53BDC1F75F0627B9504A26388E72>

> Abstract
>
> Our results show that while each studied species
> of ape and monkey can move bipedally,
> hylobatids are significantly more bipedal and
> engage in bipedal locomotion more frequently
> and for greater distances than any other primate
> sampled. These data support hypotheses of an
> orthograde, long-backed, and arboreal LCA,
> which is consistent with hominoid fossils from
> the middle-to-late Miocene.

Hylobatids are necessarily small; they rarely
come to the ground, and whenever they do,
they flee back to the safety of the trees as
quickly as they can. That is why they are
restricted to the high forests of SE Asia. Their
descendants (which led to gorillas and chimps)
had to be large enough to be able to transit
open ground, at least occasionally) before
they could migrate/expand to Africa.

However, larger apes have to be able to
scoot up trees. This means that their spines
have to be (relatively) shorter than those of
gibbons. They cannot afford to have flexible
waists. Their bodies have to form a solid,
rigid unit, powering strong muscles in their
trunks and upper thighs. In other words
they have to be similar to chimps, gorillas
and orangutans. When they progress on
the ground, they will do so quadrupedally.

> If true, knuckle-walking evolved in parallel in Pan
> and Gorilla, and the human body form,
> particularly the long lower back and orthograde
> posture, is conserved.

The long lower back and orthograde
(upright) posture is not viable in a large
primate which needs to climb trees with
ease and speed. The only 'conservation'
that is possible is in the genes: i.e. if the
taxon needs to recover a set of ancestral
traits, it can probably reactivate the
relevant genes fairly quickly.

> "The only animals in our sample with a
> combination of an orthograde body posture and a
> long lumbar region of the spine are hylobatids
> and, thus, high frequencies of bipedal locomotion
> in these lesser apes would align with aspects of
> the hylobatian model."

Not unreasonable thinking, but it
ignores both geography, and the fact
that hylobatids are restricted to SE Asia.

On Saturday, March 19, 2022 at 7:32:33 PM UTC-4, Paul Crowley wrote:
> On Friday 18 March 2022 at 17:57:24 UTC, Primum Sapienti wrote:
> > They conlcude "These lines of evidence
> > tentatively indicate that humans and
> > hylobatids reflect the ancestral body form
> > with respect to lumbar mobility and positional
> > behavior." Do note that the genetic evidence
> > places hylobatids further from humans than
> > chimpanzees...
> Hylobatids are the ancestors of all apes.
> The coding for hylobatid body form is
> in the genes of those apes, to which
> they can revert when necessary.
>
> <https://www.cambridge.org/core/journals/evolutionary-human-sciences/article/bipedal-locomotion-in-zoo-apes-revisiting-the-hylobatian-model-for-bipedal-origins/C1DC53BDC1F75F0627B9504A26388E72>
>
> > Abstract
> >
> > Our results show that while each studied species
> > of ape and monkey can move bipedally,
> > hylobatids are significantly more bipedal and
> > engage in bipedal locomotion more frequently
> > and for greater distances than any other primate
> > sampled. These data support hypotheses of an
> > orthograde, long-backed, and arboreal LCA,
> > which is consistent with hominoid fossils from
> > the middle-to-late Miocene.
> Hylobatids are necessarily small; they rarely
> come to the ground, and whenever they do,
> they flee back to the safety of the trees as
> quickly as they can. That is why they are
> restricted to the high forests of SE Asia. Their
> descendants (which led to gorillas and chimps)
> had to be large enough to be able to transit
> open ground, at least occasionally) before
> they could migrate/expand to Africa.

Sleep is absolutely critical to survival, a specific mode of locomotion is not. Hylobatids have long pregnancies indicating a previously larger body size (eg kiwi), perhaps between siamang and bonobo. Fleeing predators was secondary to beating conspecifics to food sources. Sleeping in bowl nests limited leg length but not arm size, sleeping in domeshields limited arm size but not leg size.

> However, larger apes have to be able to
> scoot up trees. This means that their spines
> have to be (relatively) shorter than those of
> gibbons. They cannot afford to have flexible
> waists. Their bodies have to form a solid,
> rigid unit, powering strong muscles in their
> trunks and upper thighs. In other words
> they have to be similar to chimps, gorillas
> and orangutans. When they progress on
> the ground, they will do so quadrupedally.
> > If true, knuckle-walking evolved in parallel in Pan
> > and Gorilla, and the human body form,
> > particularly the long lower back and orthograde
> > posture, is conserved.
> The long lower back and orthograde
> (upright) posture is not viable in a large
> primate which needs to climb trees with
> ease and speed. The only 'conservation'
> that is possible is in the genes: i.e. if the
> taxon needs to recover a set of ancestral
> traits, it can probably reactivate the
> relevant genes fairly quickly.
> > "The only animals in our sample with a
> > combination of an orthograde body posture and a
> > long lumbar region of the spine are hylobatids
> > and, thus, high frequencies of bipedal locomotion
> > in these lesser apes would align with aspects of
> > the hylobatian model."
> Not unreasonable thinking, but it
> ignores both geography, and the fact
> that hylobatids are restricted to SE Asia.

On Monday, March 21, 2022 at 5:44:53 AM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
> On Saturday, March 19, 2022 at 7:32:33 PM UTC-4, Paul Crowley wrote:
> > On Friday 18 March 2022 at 17:57:24 UTC, Primum Sapienti wrote:
> > > They conlcude "These lines of evidence
> > > tentatively indicate that humans and
> > > hylobatids reflect the ancestral body form
> > > with respect to lumbar mobility and positional
> > > behavior." Do note that the genetic evidence
> > > places hylobatids further from humans than
> > > chimpanzees...
> > Hylobatids are the ancestors of all apes.
> > The coding for hylobatid body form is
> > in the genes of those apes, to which
> > they can revert when necessary.
> >
> > <https://www.cambridge.org/core/journals/evolutionary-human-sciences/article/bipedal-locomotion-in-zoo-apes-revisiting-the-hylobatian-model-for-bipedal-origins/C1DC53BDC1F75F0627B9504A26388E72>
> >
> > > Abstract
> > >
> > > Our results show that while each studied species
> > > of ape and monkey can move bipedally,
> > > hylobatids are significantly more bipedal and
> > > engage in bipedal locomotion more frequently
> > > and for greater distances than any other primate
> > > sampled. These data support hypotheses of an
> > > orthograde, long-backed, and arboreal LCA,
> > > which is consistent with hominoid fossils from
> > > the middle-to-late Miocene.
> > Hylobatids are necessarily small; they rarely
> > come to the ground, and whenever they do,
> > they flee back to the safety of the trees as
> > quickly as they can. That is why they are
> > restricted to the high forests of SE Asia. Their
> > descendants (which led to gorillas and chimps)
> > had to be large enough to be able to transit
> > open ground, at least occasionally) before
> > they could migrate/expand to Africa.
> Sleep is absolutely critical to survival, a specific mode of locomotion is not. Hylobatids have long pregnancies indicating a previously larger body size (eg kiwi), perhaps between siamang and bonobo. Fleeing predators was secondary to beating conspecifics to food sources. Sleeping in bowl nests limited leg length but not arm size, sleeping in domeshields limited arm size but not leg size.
> > However, larger apes have to be able to
> > scoot up trees. This means that their spines
> > have to be (relatively) shorter than those of
> > gibbons. They cannot afford to have flexible
> > waists. Their bodies have to form a solid,
> > rigid unit, powering strong muscles in their
> > trunks and upper thighs. In other words
> > they have to be similar to chimps, gorillas
> > and orangutans. When they progress on
> > the ground, they will do so quadrupedally.
> > > If true, knuckle-walking evolved in parallel in Pan
> > > and Gorilla, and the human body form,
> > > particularly the long lower back and orthograde
> > > posture, is conserved.
> > The long lower back and orthograde
> > (upright) posture is not viable in a large
> > primate which needs to climb trees with
> > ease and speed. The only 'conservation'
> > that is possible is in the genes: i.e. if the
> > taxon needs to recover a set of ancestral
> > traits, it can probably reactivate the
> > relevant genes fairly quickly.
> > > "The only animals in our sample with a
> > > combination of an orthograde body posture and a
> > > long lumbar region of the spine are hylobatids
> > > and, thus, high frequencies of bipedal locomotion
> > > in these lesser apes would align with aspects of
> > > the hylobatian model."
> > Not unreasonable thinking, but it
> > ignores both geography, and the fact
> > that hylobatids are restricted to SE Asia.

Quasi-hylobatids, ancestors of all living hominoids, probably lived primarily within 100m of shallow streams, had proportions of modern hylobatid legs and modern Homo arms, and sizes between female bonobo and male siamang, and slept in tree forks with a few leafy unbent/unwoven branches added, male & female sleeping near each other but on opposite sides of tree stem (thus sounding to each other rather than seeing each other at night produced selection for dueting and calling but not for visual display, {whereas male songbirds both sing and display ornamentation while the females do neither.}).
Later Homo male-female nesting maintained adjacent domeshields where sound was conveyed but sight was not, due to leaf walls, continuing selection for conversational vocalization without olfaction pheromones or visual display, until H sapiens merged male & female domeshields into nuclear family dome huts with central hearths (eg. yurts, tipis, Pygmy huts, wikiups etc.).

On Monday 21 March 2022 at 09:44:53 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:

> Sleep is absolutely critical to survival,

Primates sleep in trees. Posture and
support arrangements vary, but none
have systematic problems.

> a specific mode of locomotion is not.

Gibbons (as such) cannot expand beyond
forests of high trees, since they are so
small, so slow and so vulnerable on the
ground.

> Hylobatids have long pregnancies indicating a previously larger
> body size

An indication, but very slight and far from
dispositive. What matters to them is their
unique and extraordinarily fast mode of
locomotion in the trees. Achieving that
determined the fundamentals of the
body shape of apes (centralised spines,
flat chests, loss of tails, poorly-positioned
hearts), even if some of their descendants
grew much larger, and ceased to be
capable of fast brachiation.

> Fleeing predators was secondary to beating conspecifics to food
> sources.

Hylobatids have no predators in their
normal habitat. But they are so vulnerable
outside its boundaries, that they can never
leave.

> Sleeping in bowl nests limited leg length but not arm
> size, sleeping in domeshields limited arm size but not leg size.

Bowl-nest fantasy, up there in la-la land
with unicorns and floating-ape babies.

On Monday, March 21, 2022 at 12:10:16 PM UTC-4, Paul Crowley wrote:
> On Monday 21 March 2022 at 09:44:53 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
>
> > Sleep is absolutely critical to survival,
> Primates sleep in trees. Posture and
> support arrangements vary, but none
> have systematic problems.

Only arboreal bowl nesting great apes have drastically shortened legs, while numerous primates scoot up trees.

> > a specific mode of locomotion is not.
> Gibbons (as such) cannot expand beyond
> forests of high trees, since they are so
> small, so slow and so vulnerable on the
> ground.

Gibbons are the second fastest primate ground bipeds. Their former range was larger, monkeys and man have intruded and reduced their range.

> > Hylobatids have long pregnancies indicating a previously larger
> > body size
> An indication, but very slight and far from
> dispositive.

It is typical of body/metabolism changes. Their trunks shrank while their limbs did not.

What matters to them is their
> unique and extraordinarily fast mode of
> locomotion in the trees.

A derived condition. Their ancestors were slower.

Achieving that
> determined the fundamentals of the
> body shape of apes (centralised spines,
> flat chests, loss of tails, poorly-positioned
> hearts), even if some of their descendants
> grew much larger, and ceased to be
> capable of fast brachiation.

Fast brachiation is derived from slow brachiation, cf avian flight, piscine swimming speed.

> > Fleeing predators was secondary to beating conspecifics to food
> > sources.
> Hylobatids have no predators in their
> normal habitat.

Eagles, owls, pythons, clouded leopards...opportunistically.

But they are so vulnerable
> outside its boundaries, that they can never
> leave.

Normal populations expand and contract with climate changes.

> > Sleeping in bowl nests limited leg length but not arm
> > size, sleeping in domeshields limited arm size but not leg size.
> Bowl-nest fantasy, up there in la-la land
> with unicorns and floating-ape babies.

Rejecting reality and adopting fantasies may be ego-soothing, but it is not scientific.

On Monday 21 March 2022 at 20:07:22 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:

>>> Sleep is absolutely critical to survival,
>>..
>> Primates sleep in trees. Posture and
>> support arrangements vary, but none
>> have systematic problems.
>.
> Only arboreal bowl nesting great apes have drastically shortened legs, while
> numerous primates scoot up trees.

I've no idea which species you think
have "drastically shortened legs" but
no one (other than you) thinks any
species of primate has legs the
length of which are determined by
its sleeping position.

> Gibbons are the second fastest primate ground bipeds.

I've no idea what this means. Over what
distances? In any case, all likely ground
predators are much faster.

>>> Hylobatids have long pregnancies indicating a previously larger
>>> body size
>>..
>> An indication, but very slight and far from
>> dispositive.
>.
> It is typical of body/metabolism changes. Their trunks shrank while their
> limbs did not.

As for all other species, their body shape
fits their niche. The can fold up their legs
while brachiating to form a ball with their
bodies, which is swung on very long arms.

>> What matters to them is their
>> unique and extraordinarily fast mode of
>> locomotion in the trees.
> .
> A derived condition.

An evolved faculty

> Their ancestors were slower.

They couldn't have been faster. Their
ancestors were monkeys that insofar
as they could brachiate at all, were
much slower at it.

>> Achieving that
>> determined the fundamentals of the
>> body shape of apes (centralised spines,
>> flat chests, loss of tails, poorly-positioned
>> hearts), even if some of their descendants
>> grew much larger, and ceased to be
>> capable of fast brachiation.
>.
> Fast brachiation is derived from slow brachiation, cf avian flight, piscine
> swimming speed.

Not in any worthwhile sense. Almost
every small monkey can brachiate --
but not with speed or comfort. One
population in one restricted locality
~ 24 ma specialised in doing so -- for
many generations -- and became the
ancestors of all gibbons and all apes.

Presumably it did not happen often
because such potential proto-gibbons
became less good at other abilities
(fast vertical climbing?) that were
important within and between
monkey species.

On Tuesday, March 22, 2022 at 7:54:45 PM UTC-4, Paul Crowley wrote:
> On Monday 21 March 2022 at 20:07:22 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
>
> >>> Sleep is absolutely critical to survival,
> >>..
> >> Primates sleep in trees. Posture and
> >> support arrangements vary, but none
> >> have systematic problems.
> >.
> > Only arboreal bowl nesting great apes have drastically shortened legs, while
> > numerous primates scoot up trees.
> I've no idea which species you think
> have "drastically shortened legs"

All great apes which sleep in arboreal bowl nests, as stated repeatedly, succinctly, correctly. That you "have no idea" is a good indicator of your persistently fallacious daydreaming, not scientific reasoning.

but
> no one (other than you) thinks any
> species of primate has legs the
> length of which are determined by
> its sleeping position.

All fauna sleep. Sleeping in a bowl nest directly influences body form, long legs don't fit.

> > Gibbons are the second fastest primate ground bipeds.
> I've no idea what this means.

More fallacy. Only humans are faster.

Over what
> distances?

All.

In any case, all likely ground
> predators are much faster.

Step away from the savannah, Gilligan.

> >>> Hylobatids have long pregnancies indicating a previously larger
> >>> body size
> >>..
> >> An indication, but very slight and far from
> >> dispositive.
> >.
> > It is typical of body/metabolism changes. Their trunks shrank while their
> > limbs did not.
> As for all other species, their body shape
> fits their niche.

Blah blah.

The can fold up their legs
> while brachiating to form a ball with their
> bodies, which is swung on very long arms.

Once more, that is modern hylobatids in fast brachiation.

> >> What matters to them is their
> >> unique and extraordinarily fast mode of
> >> locomotion in the trees.
> > .
> > A derived condition.
>
> An evolved faculty

Blah blah.
>
> > Their ancestors were slower.
>
> They couldn't have been faster.

More irrelevance.

Their
> ancestors were monkeys that insofar
> as they could brachiate at all, were
> much slower at it.

Duh.

> >> Achieving that
> >> determined the fundamentals of the
> >> body shape of apes (centralised spines,
> >> flat chests, loss of tails, poorly-positioned
> >> hearts), even if some of their descendants
> >> grew much larger, and ceased to be
> >> capable of fast brachiation.
> >.
> > Fast brachiation is derived from slow brachiation, cf avian flight, piscine
> > swimming speed.
> Not in any worthwhile sense.

Blah blah.

Almost
> every small monkey can brachiate --

Wrong.

> but not with speed or comfort. One
> population in one restricted locality
> ~ 24 ma specialised in doing so -- for
> many generations -- and became the
> ancestors of all gibbons and all apes.

Vertical posture while climbing, walking and slow brachiating.

> Presumably it did not happen often
> because such potential proto-gibbons
> became less good at other abilities
> (fast vertical climbing?) that were
> important within and between
> monkey species.

Why does parsimony terrify some people?

On Wednesday 23 March 2022 at 04:18:25 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:

>>> Only arboreal bowl nesting great apes have drastically shortened legs, while
>>> numerous primates scoot up trees.
>>..
>> I've no idea which species you think
>> have "drastically shortened legs"
>.
> All great apes which sleep in arboreal bowl nests, as stated repeatedly,
> succinctly, correctly.

If this is a common rule (for all fauna) you
will, of course, be able to quote studies
around the topic.

>> but
>> no one (other than you) thinks any
>> species of primate has legs the
>> length of which are determined by
>> its sleeping position.
>
> All fauna sleep. Sleeping in a bowl nest directly influences body form, long legs
> don't fit.

If a species needs long legs -- or long
arms -- for any reason, it's not going to
be bound by its sleeping arrangements.
It will alter them long before there's
any change in anatomy.

>>> Gibbons are the second fastest primate ground bipeds.
>>..
>> I've no idea what this means.
>
> More fallacy. Only humans are faster.

Quadrupedal chimps are much faster than
humans on the ground. The same applies
to most monkeys, e.g. baboons. (I'm
assuming that your humans are not in
cars or helicopters.)

>> In any case, all likely ground predators are much faster.
> .
> Step away from the savannah, Gilligan.

The context was the restriction of gibbons
to SE Asia, and the likelihood that they
could have spread to Europe/Africa.
There were far too many areas where
the gibbons would never have had high
canopies, and they could not have lived
in (nor traversed) open ground -- beyond
a few metres.

> Blah blah.

So articulate

>> The can fold up their legs
>> while brachiating to form a ball with their
>> bodies, which is swung on very long arms.
>..
> Once more, that is modern hylobatids in fast brachiation.

Gibbons have been around for ~23 Myr
-- doing fast brachiation.

>> Their
>> ancestors were monkeys that insofar
>> as they could brachiate at all, were
>> much slower at it.
> .
> Duh.

So articulate

>>> Fast brachiation is derived from slow brachiation, cf avian flight, piscine
>>> swimming speed.
>> Not in any worthwhile sense.
> ..
> Blah blah.

So articulate

>> Almost every small monkey can brachiate --
> .
> Wrong.

So articulate

"brachiate": to progress by swinging from hold to hold by the arms

An animal with two arms and gripping
hands can brachiate. To do it as well as
a gibbon, you need small size, long arms,
etc., etc.

>> but not with speed or comfort. One
>> population in one restricted locality
>> ~ 24 ma specialised in doing so -- for
>> many generations -- and became the
>> ancestors of all gibbons and all apes.
>.
> Vertical posture while climbing, walking and slow brachiating.

Primates often have a vertical posture
when climbing, in any brachiating they
do, and sometimes when walking.
None of this can lead (or has led) to
the drastic change in morphology that
we see in gibbons and all other apes.

>> Presumably it did not happen often
>> because such potential proto-gibbons
>> became less good at other abilities
>> (fast vertical climbing?) that were
>> important within and between
>> monkey species.
>
> Why does parsimony terrify some people?

You're confusing parsimony with vacuity.
If, for example, you remove predators
from your evolutionary scenario, you can
greatly simplify the problems that your
taxon supposedly encountered. This is
the strategy adopted by standard PA
(not that they ever set out solutions).
It's also common among the Watery Ape
theorists. It's also yours.

Another favourite device is to ignore
every significant morphological change
in the taxon, and claim "It was just a
change in the genes" or "it just happened"
or "it can be ascribed to their everyday
activities" , and in your bizarre scenario,
to the way they wanted to sleep.

That's not parsimony. It's mindlessness.

On Wednesday, March 23, 2022 at 5:49:03 PM UTC-4, Paul Crowley wrote:
> On Wednesday 23 March 2022 at 04:18:25 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
>
> >>> Only arboreal bowl nesting great apes have drastically shortened legs, while
> >>> numerous primates scoot up trees.
> >>..
> >> I've no idea which species you think
> >> have "drastically shortened legs"
> >.
> > All great apes which sleep in arboreal bowl nests, as stated repeatedly,
> > succinctly, correctly.
> If this is a common rule (for all fauna) you
> will, of course, be able to quote studies
> around the topic.
> >> but
> >> no one (other than you) thinks any
> >> species of primate has legs the
> >> length of which are determined by
> >> its sleeping position.
> >
> > All fauna sleep. Sleeping in a bowl nest directly influences body form, long legs
> > don't fit.
> If a species needs long legs -- or long
> arms -- for any reason, it's not going to
> be bound by its sleeping arrangements.
> It will alter them long before there's
> any change in anatomy.
> >>> Gibbons are the second fastest primate ground bipeds.
> >>..
> >> I've no idea what this means.
> >
> > More fallacy. Only humans are faster.
> Quadrupedal chimps are much faster than
> humans on the ground. The same applies
> to most monkeys, e.g. baboons. (I'm
> assuming that your humans are not in
> cars or helicopters.)
> >> In any case, all likely ground predators are much faster.
> > .
> > Step away from the savannah, Gilligan.
> The context was the restriction of gibbons
> to SE Asia, and the likelihood that they
> could have spread to Europe/Africa.
> There were far too many areas where
> the gibbons would never have had high
> canopies, and they could not have lived
> in (nor traversed) open ground -- beyond
> a few metres.
>
> > Blah blah.
>
> So articulate
> >> The can fold up their legs
> >> while brachiating to form a ball with their
> >> bodies, which is swung on very long arms.
> >..
> > Once more, that is modern hylobatids in fast brachiation.
> Gibbons have been around for ~23 Myr
> -- doing fast brachiation.
> >> Their
> >> ancestors were monkeys that insofar
> >> as they could brachiate at all, were
> >> much slower at it.
> > .
> > Duh.
>
> So articulate
> >>> Fast brachiation is derived from slow brachiation, cf avian flight, piscine
> >>> swimming speed.
> >> Not in any worthwhile sense.
> > ..
> > Blah blah.
>
> So articulate
> >> Almost every small monkey can brachiate --
> > .
> > Wrong.
>
> So articulate
>
> "brachiate": to progress by swinging from hold to hold by the arms
>
> An animal with two arms and gripping
> hands can brachiate. To do it as well as
> a gibbon, you need small size, long arms,
> etc., etc.
> >> but not with speed or comfort. One
> >> population in one restricted locality
> >> ~ 24 ma specialised in doing so -- for
> >> many generations -- and became the
> >> ancestors of all gibbons and all apes.
> >.
> > Vertical posture while climbing, walking and slow brachiating.
> Primates often have a vertical posture
> when climbing, in any brachiating they
> do, and sometimes when walking.
> None of this can lead (or has led) to
> the drastic change in morphology that
> we see in gibbons and all other apes.
> >> Presumably it did not happen often
> >> because such potential proto-gibbons
> >> became less good at other abilities
> >> (fast vertical climbing?) that were
> >> important within and between
> >> monkey species.
> >
> > Why does parsimony terrify some people?
> You're confusing parsimony with vacuity.
> If, for example, you remove predators
> from your evolutionary scenario, you can
> greatly simplify the problems that your
> taxon supposedly encountered. This is
> the strategy adopted by standard PA
> (not that they ever set out solutions).
> It's also common among the Watery Ape
> theorists. It's also yours.
>
> Another favourite device is to ignore
> every significant morphological change
> in the taxon, and claim "It was just a
> change in the genes" or "it just happened"
> or "it can be ascribed to their everyday
> activities" , and in your bizarre scenario,
> to the way they wanted to sleep.
>
> That's not parsimony. It's mindlessness.

The problem is that you depend entirely upon savanna chasing. As long as you do that, your claims are fluffy voids that even the brainless jerm can surpass by endlessly repeating one word: coasts! Please stop embarrassing yourself.

Op maandag 21 maart 2022 om 13:10:52 UTC+1 schreef DD'eDeN aka note/nickname/alas_my_loves:

> Quasi-hylobatids, ancestors of all living hominoids

:-DDD

My dear boy, hylobatids are as derived as gorillas, orangs, humans & chimps.

On Friday 25 March 2022 at 07:56:58 UTC, littor...@gmail.com wrote:

>> Quasi-hylobatids, ancestors of all living hominoids
>..
> My dear boy, hylobatids are as derived as gorillas, orangs, humans & chimps.

Derived from what?

The standard chest shape for terrestrial
animals -- including cercopithecoids -- is
"narrow and deep", with the heart located
at the lowest possible point when all four
limbs are touching the ground. Whereas
in apes the chest shape is "broad and
shallow".

See Figure 7 (about half-way through) in:
https://onlinelibrary.wiley.com/doi/10.1111/joa.12454#

When, why and how did the hominoid
chest evolve?

On Friday, March 25, 2022 at 3:56:58 AM UTC-4, littor...@gmail.com wrote:
> Op maandag 21 maart 2022 om 13:10:52 UTC+1 schreef DD'eDeN aka note/nickname/alas_my_loves:
> > Quasi-hylobatids, ancestors of all living hominoids
> :-DDD
>
> My dear boy, hylobatids are as derived as gorillas, orangs, humans & chimps.

Quasi-hylobatids (shorter-armed slow brachiators/bipedalists in forest canopies) preceded all hominoids.

On Friday, March 25, 2022 at 8:04:49 AM UTC-4, Paul Crowley wrote:
> On Friday 25 March 2022 at 07:56:58 UTC, littor...@gmail.com wrote:
>
> >> Quasi-hylobatids, ancestors of all living hominoids
> >..
> > My dear boy, hylobatids are as derived as gorillas, orangs, humans & chimps.
> Derived from what?
>
> The standard chest shape for terrestrial
> animals -- including cercopithecoids -- is
> "narrow and deep", with the heart located
> at the lowest possible point when all four
> limbs are touching the ground. Whereas
> in apes the chest shape is "broad and
> shallow".
>
> See Figure 7 (about half-way through) in:
> https://onlinelibrary.wiley.com/doi/10.1111/joa.12454#
>
> When, why and how did the hominoid
> chest evolve?

That paper ignores the 'built environment' of the great apes/hominins (bowl nests, domeshields) vs hylobatids, but otherwise does have other good info.

On Friday, March 25, 2022 at 8:04:49 AM UTC-4, Paul Crowley wrote:
> On Friday 25 March 2022 at 07:56:58 UTC, littor...@gmail.com wrote:
>
> >> Quasi-hylobatids, ancestors of all living hominoids
> >..
> > My dear boy, hylobatids are as derived as gorillas, orangs, humans & chimps.
> Derived from what?
>
> The standard chest shape for terrestrial
> animals -- including cercopithecoids -- is
> "narrow and deep", with the heart located
> at the lowest possible point when all four
> limbs are touching the ground. Whereas
> in apes the chest shape is "broad and
> shallow".
>
> See Figure 7 (about half-way through) in:
> https://onlinelibrary.wiley.com/doi/10.1111/joa.12454#
>
> When, why and how did the hominoid
> chest evolve?

The context demonstrates that figure 7 shows the divergence after the monkey-ape split, but the common ancestor had a skeletal frame midway between them, very typical of nonspecialized arboreal-terrestrial taxa. Though apes specialized for arboreal end-of-branch frugivory/nugivory, their ancestors had a more mixed diet.

On Friday 25 March 2022 at 12:48:10 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:

> The context demonstrates that figure 7 shows the divergence after the
> monkey-ape split,

Which of the following is more parsimonious?

A) A taxon split, into X and Y.
Both X and Y changed their forms drastically
finding new roles (or allied sets of niches) in the
forest -- abandoning their former niches.

B) A taxon split, into X and Y.
X was the old taxon, and stayed pretty much the
same, occupying the same set of long-established
niches; Y was new, and radically different -- as
the result of finding and occupying a wholly new
niche (or set of niches)

> but the common ancestor had a skeletal frame midway
> between them, very typical of nonspecialized arboreal-terrestrial taxa.

A childish conception of evolution. It's like
claiming that hominins and chimps had an
ancestor that was equally adept (and equally
clumsy) at both bipedal and quadrupedal
running & walking.

The scapulae MUST be either at the side
of the chest (as with monkeys and nearly
all mammals) or on the back (hominoids).
They can't be hovering at some midway
position.

On Friday, March 25, 2022 at 8:04:36 PM UTC-4, Paul Crowley wrote:
> On Friday 25 March 2022 at 12:48:10 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
>
> > The context demonstrates that figure 7 shows the divergence after the
> > monkey-ape split,
> Which of the following is more parsimonious?
>
> A) A taxon split, into X and Y.
> Both X and Y changed their forms drastically
> finding new roles (or allied sets of niches) in the
> forest -- abandoning their former niches.

More likely their niches abandoned them due to climate change or other externality.
See scapula position in tarsiers, lemurs, tupaia vs baboons.

>
> B) A taxon split, into X and Y.
> X was the old taxon, and stayed pretty much the
> same, occupying the same set of long-established
> niches; Y was new, and radically different -- as
> the result of finding and occupying a wholly new
> niche (or set of niches)

Less likely unless the diverging populations were separated in 2 different locations (or as in Homo, a new ground shelter evolved).

> > but the common ancestor had a skeletal frame midway
> > between them, very typical of nonspecialized arboreal-terrestrial taxa.
> A childish conception of evolution. It's like
> claiming that hominins and chimps had an
> ancestor that was equally adept (and equally
> clumsy) at both bipedal and quadrupedal
> running & walking.

Nope, entirely wrong. Upright bipedal habit allows scapula to shift, palmigrade pronograde quadrupedalism forbids shift, ape knucklewalking allows the shift.

> The scapulae MUST be either at the side
> of the chest (as with monkeys and nearly
> all mammals) or on the back (hominoids).
> They can't be hovering at some midway
> position.

They certainly did at the LCA monkey/ape split, in association with arboreal bipedalism and slow brachiation initiation.

I was seeking if birds had scapula more like monkeys-dogs on side of thorax, or apes-humans on back.

https://chickenandchicksinfo.com/do-chickens-have-shoulders/

I guess there is a parallel between white vs brown fat and white meat (chicken breast light because rarely flies) and dark meat (pheasant breast dark because strong flier), mitochondria higher in dark tissue. (Reminds me of O2-bearing myoglobin in whale meat being dark, but not sure if related. Is whale blubber white or black fat?)

Chicken shoulder meat is called 'oyster', a delicacy in Japan.

Avian scapulae are of medullary bone, store calcium for eggs, not hollow for flight like wing bones.

Proto-birds used WAIR to climb trees, Wing Assisted Incline Running, where the arms didn't need to grasp branches to climb. I witnessed a duck doing this last month.

On Friday, March 25, 2022 at 10:46:58 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
> On Friday, March 25, 2022 at 8:04:36 PM UTC-4, Paul Crowley wrote:
> > On Friday 25 March 2022 at 12:48:10 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
> >
> > > The context demonstrates that figure 7 shows the divergence after the
> > > monkey-ape split,
> > Which of the following is more parsimonious?
> >
> > A) A taxon split, into X and Y.
> > Both X and Y changed their forms drastically
> > finding new roles (or allied sets of niches) in the
> > forest -- abandoning their former niches.
> More likely their niches abandoned them due to climate change or other externality.
> See scapula position in tarsiers, lemurs, tupaia vs baboons.
> >
> > B) A taxon split, into X and Y.
> > X was the old taxon, and stayed pretty much the
> > same, occupying the same set of long-established
> > niches; Y was new, and radically different -- as
> > the result of finding and occupying a wholly new
> > niche (or set of niches)
> Less likely unless the diverging populations were separated in 2 different locations (or as in Homo, a new ground shelter evolved).
> > > but the common ancestor had a skeletal frame midway
> > > between them, very typical of nonspecialized arboreal-terrestrial taxa.
> > A childish conception of evolution. It's like
> > claiming that hominins and chimps had an
> > ancestor that was equally adept (and equally
> > clumsy) at both bipedal and quadrupedal
> > running & walking.
> Nope, entirely wrong. Upright bipedal habit allows scapula to shift, palmigrade pronograde quadrupedalism forbids shift, ape knucklewalking allows the shift.
> > The scapulae MUST be either at the side
> > of the chest (as with monkeys and nearly
> > all mammals) or on the back (hominoids).
> > They can't be hovering at some midway
> > position.
> They certainly did at the LCA monkey/ape split, in association with arboreal bipedalism and slow brachiation initiation.
>
>
> I was seeking if birds had scapula more like monkeys-dogs on side of thorax, or apes-humans on back.
>
> https://chickenandchicksinfo.com/do-chickens-have-shoulders/
>
> I guess there is a parallel between white vs brown fat and white meat (chicken breast light because rarely flies) and dark meat (pheasant breast dark because strong flier), mitochondria higher in dark tissue. (Reminds me of O2-bearing myoglobin in whale meat being dark, but not sure if related. Is whale blubber white or black fat?)
>
> Chicken shoulder meat is called 'oyster', a delicacy in Japan.
>
> Avian scapulae are of medullary bone, store calcium for eggs, not hollow for flight like wing bones.
>
> Proto-birds used WAIR to climb trees, Wing Assisted Incline Running, where the arms didn't need to grasp branches to climb. I witnessed a duck doing this last month.

A recently described behavior, wing-assisted incline running (WAIR), documents the use of wings to enable bipedal ground birds to `run' up vertical surfaces(Dial, 2003). This challenging and unexpected activity requires that in contrast to the traditional function of supplying thrust in the direction of travel and lift to support body weight, the wings of ground birds act to enhance hindlimb function(Dial, 2003). Specifically,the WAIR hypothesis suggests that during a substantial portion of the wingbeat cycle the wings of ground birds act to accelerate these animals towards the substrate.

WAIR has been documented in the juveniles and adults of four species of ground birds, and involves the simultaneous use of flapping wings and running legs to ascend steep inclines (Dial,2003). WAIR permits extant ground birds, and may have permitted proto-birds, to use their hindlimbs more effectively in retreat to elevated refuges (cliffs, boulders, trees, etc.). It has been hypothesized that as these animals negotiate precipitous inclines (>60°), they alter their normal flight stroke to develop aerodynamic forces that secure the animal's feet upon the substrate, essentially functioning like the spoiler on a racecar, to enhance traction (Dial,2003).

Note: Proto-birds had claws, primates nails.
Note: Monkeys have quadrupedal dog-like thorax, but lemurs & tarsiers never run quadrupedally. Monkey quadrupedalism is novel, as is ape bipedalism and derived knucklewalking quadrupedalism.

On Saturday, March 26, 2022 at 1:37:40 AM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
> On Friday, March 25, 2022 at 10:46:58 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
> > On Friday, March 25, 2022 at 8:04:36 PM UTC-4, Paul Crowley wrote:
> > > On Friday 25 March 2022 at 12:48:10 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
> > >
> > > > The context demonstrates that figure 7 shows the divergence after the
> > > > monkey-ape split,
> > > Which of the following is more parsimonious?
> > >
> > > A) A taxon split, into X and Y.
> > > Both X and Y changed their forms drastically
> > > finding new roles (or allied sets of niches) in the
> > > forest -- abandoning their former niches.
> > More likely their niches abandoned them due to climate change or other externality.
> > See scapula position in tarsiers, lemurs, tupaia vs baboons.
> > >
> > > B) A taxon split, into X and Y.
> > > X was the old taxon, and stayed pretty much the
> > > same, occupying the same set of long-established
> > > niches; Y was new, and radically different -- as
> > > the result of finding and occupying a wholly new
> > > niche (or set of niches)
> > Less likely unless the diverging populations were separated in 2 different locations (or as in Homo, a new ground shelter evolved).
> > > > but the common ancestor had a skeletal frame midway
> > > > between them, very typical of nonspecialized arboreal-terrestrial taxa.
> > > A childish conception of evolution. It's like
> > > claiming that hominins and chimps had an
> > > ancestor that was equally adept (and equally
> > > clumsy) at both bipedal and quadrupedal
> > > running & walking.
> > Nope, entirely wrong. Upright bipedal habit allows scapula to shift, palmigrade pronograde quadrupedalism forbids shift, ape knucklewalking allows the shift.
> > > The scapulae MUST be either at the side
> > > of the chest (as with monkeys and nearly
> > > all mammals) or on the back (hominoids).
> > > They can't be hovering at some midway
> > > position.
> > They certainly did at the LCA monkey/ape split, in association with arboreal bipedalism and slow brachiation initiation.
> >
> >
> > I was seeking if birds had scapula more like monkeys-dogs on side of thorax, or apes-humans on back.
> >
> > https://chickenandchicksinfo.com/do-chickens-have-shoulders/
> >
> > I guess there is a parallel between white vs brown fat and white meat (chicken breast light because rarely flies) and dark meat (pheasant breast dark because strong flier), mitochondria higher in dark tissue. (Reminds me of O2-bearing myoglobin in whale meat being dark, but not sure if related. Is whale blubber white or black fat?)
> >
> > Chicken shoulder meat is called 'oyster', a delicacy in Japan.
> >
> > Avian scapulae are of medullary bone, store calcium for eggs, not hollow for flight like wing bones.
> >
> > Proto-birds used WAIR to climb trees, Wing Assisted Incline Running, where the arms didn't need to grasp branches to climb. I witnessed a duck doing this last month.
> A recently described behavior, wing-assisted incline running (WAIR), documents the use of wings to enable bipedal ground birds to `run' up vertical surfaces(Dial, 2003). This challenging and unexpected activity requires that in contrast to the traditional function of supplying thrust in the direction of travel and lift to support body weight, the wings of ground birds act to enhance hindlimb function(Dial, 2003). Specifically,the WAIR hypothesis suggests that during a substantial portion of the wingbeat cycle the wings of ground birds act to accelerate these animals towards the substrate.
>
> WAIR has been documented in the juveniles and adults of four species of ground birds, and involves the simultaneous use of flapping wings and running legs to ascend steep inclines (Dial,2003). WAIR permits extant ground birds, and may have permitted proto-birds, to use their hindlimbs more effectively in retreat to elevated refuges (cliffs, boulders, trees, etc.). It has been hypothesized that as these animals negotiate precipitous inclines (>60°), they alter their normal flight stroke to develop aerodynamic forces that secure the animal's feet upon the substrate, essentially functioning like the spoiler on a racecar, to enhance traction (Dial,2003).
>
> Note: Proto-birds had claws, primates nails.
> Note: Monkeys have quadrupedal dog-like thorax, but lemurs & tarsiers never run quadrupedally. Monkey quadrupedalism is novel, as is ape bipedalism and derived knucklewalking quadrupedalism.

Note the broad thorax of the arboreal tarsier: https://images.app.goo.gl/q569P7f96iu5ED1X7

DD'eDeN aka note/nickname/alas_my_loves wrote:

> A recently described behavior, wing-assisted incline running (WAIR), documents the use of wings to enable bipedal ground birds to `run' up vertical surfaces(Dial, 2003). This challenging and unexpected activity requires that in contrast to the traditional function of supplying thrust in the direction of travel and lift to support body weight, the wings of ground birds act to enhance hindlimb function(Dial, 2003).

They're all secondarily flightless!

Are you actually trying to pretend that wings evolved as a way for flightless birds
to climb because flying was an evolutionary failure?

They're secondarily flightless. They evolved from fully flying ancestors.

-- --

https://jtem.tumblr.com/post/679763679359680512

On Saturday, March 26, 2022 at 2:23:15 AM UTC-4, I Envy JTEM wrote:
> DD'eDeN aka note/nickname/alas_my_loves wrote:
>
> > A recently described behavior, wing-assisted incline running (WAIR), documents the use of wings to enable bipedal ground birds to `run' up vertical surfaces(Dial, 2003). This challenging and unexpected activity requires that in contrast to the traditional function of supplying thrust in the direction of travel and lift to support body weight, the wings of ground birds act to enhance hindlimb function(Dial, 2003).
> They're all secondarily flightless!
>
> Are you actually trying to pretend that wings evolved as a way for flightless birds
> to climb because flying was an evolutionary failure?
>
> They're secondarily flightless. They evolved from fully flying ancestors.
>
>
>
>
>
>
> -- --
>
> https://jtem.tumblr.com/post/679763679359680512

"Ground birds" as opposed to seabirds, arboreal songbirds, raptors etc. do not refer to completely non-flying birds (emu, ostrich, cassowary, flightless cranes, penguins etc) but rather to poorly-flying birds which spend most of their time (not all) on the ground but can fly for short periods up to tree branches or across rivers, etc. as can chickens, grouse, prairie chickens, turkeys, some waterfowl, peacocks, none of which are "secondarily flightless".

On Saturday 26 March 2022 at 02:46:58 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:

>> Which of the following is more parsimonious?
>>..
>> A) A taxon split, into X and Y.
>> Both X and Y changed their forms drastically
>> finding new roles (or allied sets of niches) in the
>> forest -- abandoning their former niches.
>.
> More likely their niches abandoned them due to climate change or other externality.

Essentially nonsense. Gibbons have been around
for 20+ Myr. Large apes: chimps/gorillas/orangs
for 10+

>> B) A taxon split, into X and Y.
>> X was the old taxon, and stayed pretty much the
>> same, occupying the same set of long-established
>> niches; Y was new, and radically different -- as
>> the result of finding and occupying a wholly new
>> niche (or set of niches)
>.
> Less likely unless the diverging populations were separated in
> 2 different locations (or as in Homo, a new ground shelter evolved).

Separation for a few 100 K years (or even
a million) is common. See Bonobos --
presumably the Congo river changed its
course. In this case both populations
continued (more-or-less) in their ancient
niches.

> See scapula position in tarsiers, lemurs, tupaia vs baboons.

You'd need to study live animals to see
where their scapulae are located. but
these animals are so small, that their
location is almost irrelevant. Tarsiers
weigh around 100 grams -- half an apple or
two medium eggs. Tupaia are only slightly
larger. These are tiny, nearly mouse-sized.
Size matters. Muscle power and bone
strength scale more than proportionately.

That's highly relevant when a taxon with
a new body form comes into existence.
Smaller animals can afford much more
plasticity. Modern small gibbons weigh
~5 kg. The very first ones were probably
less than half that. A monkey of that size
could brachiate to some extent -- much
better than one double its size with the
same anatomy. If the circumstances
favoured more of that activity, the small
monkey could readily specialise in it.

>>> but the common ancestor had a skeletal frame midway
>>> between them, very typical of nonspecialized arboreal-terrestrial taxa.
>>..
>> A childish conception of evolution. It's like
>> claiming that hominins and chimps had an
>> ancestor that was equally adept (and equally
>> clumsy) at both bipedal and quadrupedal
>> running & walking.
>..
> Nope, entirely wrong. Upright bipedal habit allows scapula to shift,

Firstly, we're talking about chests,
and the bones and ligaments around
them. Bipedalism is primarily about
legs and the pelvis. Secondly, it's
about evolutionary developments
before 20 ma when there were no
bipeds.

If you were right, you should be able to
refer to numerous primate (& other?)
species (> ~2kg) which have scapula in
the gibbon/hominoid position -- on
their backs. Let's see the list.

Hominoid chests became shallow and
broad so that the spinal column could
be central. That was to enable fast
brachiation. Find other mammals >~2kg
with shallow, broad chests.

> palmigrade pronograde quadrupedalism forbids shift, ape knucklewalking
> allows the shift.

Nonsense on every level. K/walking is
quadrupedal, with a horizontal trunk.