Knuckle-walking in Sahelanthropus?
Locomotor inferences from the ulnae of fossil hominins and other hominoids
Marc R Meyer cs 2023 JHE 179,103355
doi org/10.1016/j.jhevol.2023.103355

The ulna supports & transmits forces during movement:
its morphology can signal aspects of functional adaptation.
Did some hominins (like extant apes) habitually recruit the forelimb in locomotion?
We separate the ulna shaft & ulna proximal complex for independent shape analyses (elliptical Fourier methods), to identify functional signals.
We examine the rel. influence of locomotion, taxonomy & body-mass on ulna contours:
22 Hs, 33 extant (5 spp) & 2 Miocene apes (Hispanopith. & Danuvius), 17 fossil hominin spms: Sahelanthr., Ardipith., Australopith., Paranthropus, early Homo.

Ulna proximal complex contours correlate with body-mass, but not locomotor patterns,
ulna shafts significantly correlate with locomotion.
Afr.apes' ulna shafts are
- more robust & curved than Asian apes',
- unlike other terrestrial mammals (incl. other primates), curving ventrally rather than dorsally,
this distinctive curvature is absent in orangs & hylobatids:
it is likely a function of powerful flexors, engaged in wrist+hand stabilization during KWing, not an adaptation to climbing or suspension.

OH-36 (Par.boisei?) & TM-266 (Sahelanthr.tchadensis?) differ from other hominins:
they fall within the KWing morpho-space = forelimb morphology cons.x terrestrial locomotion.
Discriminant function analysis classifies OH-36 & TM-266 with Pan & Gorilla, with high posterior probability.
Along with its associated femur, the TM-266 ulna shaft contours & its deep, keeled trochlear notch comprise a suite of traits signaling Afr.ape-like QPalism.

Implications for the phylogenetic position & hominin status of Sah.tchadensis remain equivocal,("hominin"??--mv)
but this study supports the growing body of evidence:
Sah.tchadensis was not an obligate BP, but a late-Miocene hominid with KWing adaptations.

_____

:-)

On Sat, 1 Apr 2023 03:53:39 -0700 (PDT), "littor...@gmail.com"
<littoral.homo@gmail.com> wrote:

>Knuckle-walking in Sahelanthropus?
>Locomotor inferences from the ulnae of fossil hominins and other hominoids
>Marc R Meyer cs 2023 JHE 179,103355
>doi org/10.1016/j.jhevol.2023.103355
>
>The ulna supports & transmits forces during movement:
>its morphology can signal aspects of functional adaptation.
>Did some hominins (like extant apes) habitually recruit the forelimb in locomotion?
>We separate the ulna shaft & ulna proximal complex for independent shape analyses (elliptical Fourier methods), to identify functional signals.
>We examine the rel. influence of locomotion, taxonomy & body-mass on ulna contours:
>22 Hs, 33 extant (5 spp) & 2 Miocene apes (Hispanopith. & Danuvius), 17 fossil hominin spms: Sahelanthr., Ardipith., Australopith., Paranthropus, early Homo.
>
>Ulna proximal complex contours correlate with body-mass, but not locomotor patterns,
>ulna shafts significantly correlate with locomotion.
>Afr.apes' ulna shafts are
>- more robust & curved than Asian apes',
>- unlike other terrestrial mammals (incl. other primates), curving ventrally rather than dorsally,
>this distinctive curvature is absent in orangs & hylobatids:
>it is likely a function of powerful flexors, engaged in wrist+hand stabilization during KWing, not an adaptation to climbing or suspension.
>
>OH-36 (Par.boisei?) & TM-266 (Sahelanthr.tchadensis?) differ from other hominins:

OH 36 is category C-3 sensu Grine et al. (2022): Low confidence
taxonomic attribution, isolated postcranial bones that lack a
taxon-specific temporal and/or geographic context.
https://www.sciencedirect.com/science/article/abs/pii/S0047248422001154

The same goes for L40-19 from Omo Shungura, which Meyer cs. also
assign to P. boisei and classify as "Suspensory" (Table 2).

All A. afarensis specimens (A.L.438-1, A.L.288-1, KSD-VP-1/1) are
classified as "Bipedal".

>they fall within the KWing morpho-space = forelimb morphology cons.x terrestrial locomotion.
>Discriminant function analysis classifies OH-36 & TM-266 with Pan & Gorilla, with high posterior probability.
>Along with its associated femur, the TM-266 ulna shaft contours & its deep, keeled trochlear notch comprise a suite of traits signaling Afr.ape-like QPalism.
>
>Implications for the phylogenetic position & hominin status of Sah.tchadensis remain equivocal,("hominin"??--mv)
>but this study supports the growing body of evidence:
>Sah.tchadensis was not an obligate BP, but a late-Miocene hominid with KWing adaptations.

They also classify StW 573, "Little Foot", a nearly complete
Australopithecus skeleton from Sterkfontein as "Knuckle-walking",
while the total skeletal morphology of this specimen clearly indicates
habitual bipedalism with some degree of arborealism.
Moreover, "the hand morphology and the limb ratios of StW 573 bear no
anatomical evidence that it was a knuckle-walker."
https://www.karger.com/Article/FullText/519723

Locomotor inferences should not be based on morphometrics of single
skeletal elements.

> >Knuckle-walking in Sahelanthropus?
> >Locomotor inferences from the ulnae of fossil hominins and other hominoids
> >Marc R Meyer cs 2023 JHE 179,103355 doi org/10.1016/j.jhevol.2023.103355
> >The ulna supports & transmits forces during movement:
> >its morphology can signal aspects of functional adaptation.
> >Did some hominins (like extant apes) habitually recruit the forelimb in locomotion?
> >We separate the ulna shaft & ulna proximal complex for independent shape analyses (elliptical Fourier methods), to identify functional signals.
> >We examine the rel. influence of locomotion, taxonomy & body-mass on ulna contours:
> >22 Hs, 33 extant (5 spp) & 2 Miocene apes (Hispanopith. & Danuvius), 17 fossil hominin spms: Sahelanthr., Ardipith., Australopith., Paranthropus, early Homo.
> >Ulna proximal complex contours correlate with body-mass, but not locomotor patterns,
> >ulna shafts significantly correlate with locomotion.
> >Afr.apes' ulna shafts are
> >- more robust & curved than Asian apes',
> >- unlike other terrestrial mammals (incl. other primates), curving ventrally rather than dorsally,
> >this distinctive curvature is absent in orangs & hylobatids:
> >it is likely a function of powerful flexors, engaged in wrist+hand stabilization during KWing, not an adaptation to climbing or suspension.
> >OH-36 (Par.boisei?) & TM-266 (Sahelanthr.tchadensis?) differ from other hominins:

Kudu runner:
> OH 36 is category C-3 sensu Grine et al. (2022): Low confidence
> taxonomic attribution, isolated postcranial bones that lack a
> taxon-specific temporal and/or geographic context.
> https://www.sciencedirect.com/science/article/abs/pii/S0047248422001154
> The same goes for L40-19 from Omo Shungura, which Meyer cs. also
> assign to P. boisei and classify as "Suspensory" (Table 2).
> All A. afarensis specimens (A.L.438-1, A.L.288-1, KSD-VP-1/1) are
> classified as "Bipedal".

Are you really incapable to understand?? or do you only pretend?
Today only humans & hylobatids are still BP, but *all* Hominoidea had BP ancestors:
they waded upright in swamp forests & climbed arms overhead in the branches above the water,
this is still seen occasionally (in spite of Pleist.coolings?) in bonobos, lowland gorillas & orangutans:
google "bonobo wading" or "aquarboreal" etc.

> >they fall within the KWing morpho-space = forelimb morphology cons.x terrestrial locomotion.
> >Discriminant function analysis classifies OH-36 & TM-266 with Pan & Gorilla, with high posterior probability.
> >Along with its associated femur, the TM-266 ulna shaft contours & its deep, keeled trochlear notch comprise a suite of traits signaling Afr.ape-like QPalism.
> >Implications for the phylogenetic position & hominin status of Sah.tchadensis remain equivocal,("hominin"??--mv)
> >but this study supports the growing body of evidence:
> >Sah.tchadensis was not an obligate BP, but a late-Miocene hominid with KWing adaptations.

> They also classify StW 573, "Little Foot", a nearly complete
> Australopithecus skeleton from Sterkfontein as "Knuckle-walking",
> while the total skeletal morphology of this specimen clearly indicates
> habitual bipedalism with some degree of arborealism.
> Moreover, "the hand morphology and the limb ratios of StW 573 bear no
> anatomical evidence that it was a knuckle-walker."
> https://www.karger.com/Article/FullText/519723
> Locomotor inferences should not be based on morphometrics of single
> skeletal elements.

*Everything* points into the same direction: as I argued already a few times,
more frequent KWing began apparently a few mill.yrs earlier in Gorilla (E.Afr.apiths cs) than in Pan (S.Afr.apiths).

On Saturday, April 1, 2023 at 11:45:50 AM UTC-7, littor...@gmail.com wrote:
> > >Knuckle-walking in Sahelanthropus?
> > >Locomotor inferences from the ulnae of fossil hominins and other hominoids
> > >Marc R Meyer cs 2023 JHE 179,103355 doi org/10.1016/j.jhevol.2023.103355
> > >The ulna supports & transmits forces during movement:
> > >its morphology can signal aspects of functional adaptation.
> > >Did some hominins (like extant apes) habitually recruit the forelimb in locomotion?
> > >We separate the ulna shaft & ulna proximal complex for independent shape analyses (elliptical Fourier methods), to identify functional signals.
> > >We examine the rel. influence of locomotion, taxonomy & body-mass on ulna contours:
> > >22 Hs, 33 extant (5 spp) & 2 Miocene apes (Hispanopith. & Danuvius), 17 fossil hominin spms: Sahelanthr., Ardipith., Australopith., Paranthropus, early Homo.
> > >Ulna proximal complex contours correlate with body-mass, but not locomotor patterns,
> > >ulna shafts significantly correlate with locomotion.
> > >Afr.apes' ulna shafts are
> > >- more robust & curved than Asian apes',
> > >- unlike other terrestrial mammals (incl. other primates), curving ventrally rather than dorsally,
> > >this distinctive curvature is absent in orangs & hylobatids:
> > >it is likely a function of powerful flexors, engaged in wrist+hand stabilization during KWing, not an adaptation to climbing or suspension.
> > >OH-36 (Par.boisei?) & TM-266 (Sahelanthr.tchadensis?) differ from other hominins:
> Kudu runner:
> > OH 36 is category C-3 sensu Grine et al. (2022): Low confidence
> > taxonomic attribution, isolated postcranial bones that lack a
> > taxon-specific temporal and/or geographic context.
> > https://www.sciencedirect.com/science/article/abs/pii/S0047248422001154
> > The same goes for L40-19 from Omo Shungura, which Meyer cs. also
> > assign to P. boisei and classify as "Suspensory" (Table 2).
> > All A. afarensis specimens (A.L.438-1, A.L.288-1, KSD-VP-1/1) are
> > classified as "Bipedal".
> Are you really incapable to understand?? or do you only pretend?

Understand what? You don't even write in complete sentences, you convoluted moron.

> Today only humans & hylobatids are still BP, but *all* Hominoidea had BP ancestors:
> they waded upright in swamp forests & climbed arms overhead in the branches above the water,

So the fuck what? They occasionally waded. They occasionally brachiated. WHO THE FUCK CARES?

> this is still seen occasionally (in spite of Pleist.coolings?) in bonobos, lowland gorillas & orangutans:
> google "bonobo wading" or "aquarboreal" etc.

Occasional wading? Are you fucking retarded? Seriously. How do you two morons expect anybody to take you seriously?

> > >they fall within the KWing morpho-space = forelimb morphology cons.x terrestrial locomotion.
> > >Discriminant function analysis classifies OH-36 & TM-266 with Pan & Gorilla, with high posterior probability.
> > >Along with its associated femur, the TM-266 ulna shaft contours & its deep, keeled trochlear notch comprise a suite of traits signaling Afr.ape-like QPalism.
> > >Implications for the phylogenetic position & hominin status of Sah.tchadensis remain equivocal,("hominin"??--mv)
> > >but this study supports the growing body of evidence:
> > >Sah.tchadensis was not an obligate BP, but a late-Miocene hominid with KWing adaptations.
>
> > They also classify StW 573, "Little Foot", a nearly complete
> > Australopithecus skeleton from Sterkfontein as "Knuckle-walking",
> > while the total skeletal morphology of this specimen clearly indicates
> > habitual bipedalism with some degree of arborealism.
> > Moreover, "the hand morphology and the limb ratios of StW 573 bear no
> > anatomical evidence that it was a knuckle-walker."
> > https://www.karger.com/Article/FullText/519723
> > Locomotor inferences should not be based on morphometrics of single
> > skeletal elements.
> *Everything* points into the same direction: as I argued already a few times,
> more frequent KWing began apparently a few mill.yrs earlier in Gorilla (E..Afr.apiths cs) than in Pan (S.Afr.apiths).

You vague, nitwits are perfectly unaware of confirmation bias?

Neither of you idiots has any business in a scientific discussion.

littor...@gmail.com wrote:

> Implications for the phylogenetic position & hominin status of Sah.tchadensis remain equivocal,("hominin"??--mv)
> but this study supports the growing body of evidence:
> Sah.tchadensis was not an obligate BP, but a late-Miocene hominid with KWing adaptations.

The foramen magnum is just plain wrong for a Chimp or Gorilla. It
appears MORE, not less, bipedal than Ardi and the claim is that is is
less bipedal than Lucy but just Google them! They look very close,
and it definitely looks more bipedal than any other Australopithecus!

The closer to the back of the skull, the less bipedal...

One may argue that Sahelanthropus was caught within the midst of
evolving *Away* from bipedal locomotion to knuckle walking, or the
idiots are simply defending their precious Out of Africa narrative and
Sahelanthropus is "To soon" for them.

NOTE: Sahelanthropus is presently dated to about 2 million years
AFTER what I would identify as a peak era for selective pressures
favoring Aquatic Ape/Bipedal adaptations... which was roughly 8.7
million years ago due to a super volcanic eruption.

That 2 million years IS enough time for a whole new species to
arise, so maybe Sahelanthropus is a step away from bipedal: Maybe
it really did have ancestors that were significantly more adapted to
bipedal locomotion!

Or, yeah, they're crazy.

-- --

https://jtem.tumblr.com/post/713529832816902144