Op 10-09-2021 12:10 schreef DDeden <daud.deden@gmail.com>:
Miocene apes swam like monkeys, had no enlarged laryngeal air sacs, were not swamp-dependent.

MV No: large size & tail loss.

They were not large, did not swim often, tail-lessness comparable to Celebes macaque or Atlas Barbary macaque.

On Fri, Sep 10, 2021, 6:05 AM <m_verhaegen@skynet.be> wrote:
The earliest hominoids (e.g. Proconsul) were already aquarboreal: larger size & tail loss. But already broad sternum-thorax-pelvis?
Curved proximal phalanges suggest also below-branch locomotion.

Yes, slow brachiation.

The long thumb was probably for grasping, perhaps already also for swimming?

Little swimming, thumb still monkey-like.

Op 10-09-2021 11:49 schreef DDeden <daud.deden@gmail.com>: https://groups.io/g/AAT/message/72345
Did the H/P LCA display extant-ape-like hand proportions:
- rel.long fingers

Yes, but shorter than chimps

- a short thumb?

No, that occurred with faster brachiation.
See rudapithicus post.


Here we describe new pollical remains: a complete proximal phalanx & a partial distal phalanx (mid-/late-Miocene Castell de Barberà c 11.2–10.5 Ma, Vallès-Penedès Basin),
we provide morphometric & qualitative comparisons with other available Miocene spms & extant catarrhines incl.humans.
Results: all available Miocene taxa (Proconsul, Nachola-, Afro-, Siva-, Hispano-, Oreopithecus & Castell de Barberà) share a similar phalangeal thumb morphology:
the phalanges are rel.long,
the proximal phalanges have
- a high degree of curvature,
- marked insertions for the flexor muscles,
- a palmarly bent trochlea,
- a low basal height.
All these features suggest:
- these Miocene apes used their thumb with an emphasis on flexion, most of them to powerfully assist the fingers during above-branch, grasping arboreal locomotion,
- in terms of relative proximal phalangeal length, the thumb of Miocene taxa is intermediate between the long-thumbed humans & the short-thumbed extant apes.
Together with previous evidence, this suggests:
a moderate-length hand with rel.long thumb (involved in locomotion) is the original hominid hand morpho-type.
____

They err in claiming the longish thumb indicates only above-branch climbing. Early hominoids were above-branch bipeds using their hands above to grasp branches positionally, strip green bark (pinching = long thumb), plucking hanging fruit & nuts, and they did the same below branch while bimanually suspended, using their feet to
manipulate; and they used **slow** brachiation (not hooking like modern apes, just grasping branch above and swinging a bit while reaching for the next branch).
I've referred to these as quasi-hylobatids, with shorter arms and longer thumbs than modern apes.


DD

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