Op maandag 29 november 2021 om 07:24:57 UTC+1 schreef DD'eDeN aka note/nickname/alas_my_loves:
Ischial Form as an Indicator of Bipedal Kinematics in Early Hominins:
a Test Using Extant Anthropoids
Kristi L Lewton & Jeremiah Scott 2017
Anat Rec 300:845–858
Human ischia (vs great apes) are
- cranio-caudally short,
- dorsally projecting.
This is thought to facilitate greater hip extension in Hs BPism.
This link has been used to infer kinematics in early hominins,
but the consequences of variation in ischial configuration for gait remain uncertain.
Kinematic data for a limited sample of extant non-human primates demonstrate:
there is variation in hip extension in these taxa during BP behaviors:
Hylobates & Ateles are capable of greater extension than Pan & Macaca.
In this study, we tested:
are ischial length & orientation functionally linked with hip extension during BP among these taxa?
As expected, Hs have the shortest ischia, followed by gibbon, spider monkey, chimp & macaque.
But our predictions for ischial orientation are not supported:
- macaques, gibbons & spider monkeys do not vary in this trait,
- they have ischia that are less dorsally angled than chimps.
The results for ischium length provide limited support for the idea that
- the early hominin Ardipithecus ramidus (with its long, caudally oriented ischium) was not capable of humanlike extended-hip BPism,
- the ischial shortening observed in post-Ardipithecus hominins reflects a shift toward a more human-like gait.
our results do not necessarily refute a link between ischial orientation & hip extension in hominins,
but they do not provide comparative support, making changes in ischial orientation in this part of the fossil record more difficult to interpret.
Simply google "aquarboreal".
All Mio-Pliocene hominoids (incl."hominins") were "BP", not for running after antelopes, but simply for wading upright & climbing arms overhead in the branches above the swamp.
This is occasionally still seen (prediced by us :-)) in great apes:
- lowland gorillas wading for sedges,
- bonobos wading for waterlilies.