Re: Plate Tectonics & hominoid splittings?
I have a new theory of what caused the ape/OWM split, and I think it happened in East Africa.toggle quoted messageShow quoted text
25+ Ma continental plate tectonics pushed up against East Africa starting to form the rift. This pushed the eastern seaboard upwards and caused rivers to run backwards, forming the great East African lakes. It would also have flooded the forests and created forested islands, especially in and around lake Victoria. (Roberts, et al., 2012)
The earliest fossil evidence comes from 2 species, dating to 25.2 Ma from the Rift Basin of Tanzania: Rukwapithecus fleaglei appears to be more hominoid whereas Nsungwepithecus gunnelli appears to be more OWM (Stevens, et al., 2013).
I believe the apes diverged by becoming more aquarboareal, climbing down the trunks to exploit newly available niches in the flooded forests, while the monkeys remained more arboreal. Over time these apes became bigger in size, more orthograde, longer armed, flatter thoraxes, etc. and they lost their tails. (Verhaegen, et al.)
Morotopithecus at 21 Ma represents one of the first fully orthograde apes.
Sometime between 22 - 18 Ma they Hylobatids diverged. Their ancestor made their way to Asia, perhaps over the gomphotherium land bridge (20-19 Ma), and it was there that they returned to the tree tops, became smaller, etc. (Hence why no hylobatids in Africa).
Hominoid apes, e.g. Helipithecus, occupied the Arabian continent / coastal forests around 17 - 16 Ma.
Some form of Griphopithecus made it all the way to central Europe by 16.5 Ma and apes diversified into many different species between 16- 11 Ma, mostly Aquarboreal, orthograde and always close to water. (Europe was very hot, flooded, wet at that time - many inland seas). It was around that time that Pongo diverged and set off for Asia.
11 - 9 Ma - Vallesian crisis - (loss of forest, increase in grassland savannah, arrival of many predators, seasonal food availability) caused most apes to go extinct. A few survived into the late Miocene.
Ouranopithecus (9.8 Ma) may be a branch of the gorilla line that returned to Africa, c. 10 Ma. (de Bonis, et al.)
Graecopithecus (7.2 Ma) may have been close to the LCA of Pan/Homo. (Fuss, Boheme, Spassov, et al, 2017)
Trachilos shows bipedal hominines in Crete 6.0 Ma. (Gierlinski / Spassov, et al.)
5.9 - 5.3 Ma - the Messinian Salinity Crisis - time to leave!
5.3 Ma - the Zanclean flood cut off the route between Arabia and Africa.
Those that made it across to Africa before the flood followed the African coast of the Red Sea, followed the Rift and eventually all the way down to South Africa, becoming over time less semi-aquatic / more arboreal (Pan).
Those that didn't make it across in time, colonised the Arabian coast of the Red Sea throughout the Pliocene, becoming increasingly aquatic (Homo).
2.6 Ma, Pleistocene cooling and drop in sea-levels.
Pan/Homo come together again at the southern end of the Red Sea / Afar / Rift Valley = Homo habilis
2.5 - 2.0 Ma - the great radiation of Homo out of the Red Sea (north to Georgia, East to China / Indonesia, West to Africa, etc.) (Mansfield, 😊 2022)
From: AAT@groups.io <AAT@groups.io> On Behalf Of Marc Verhaegen
Sent: Saturday, March 26, 2022 2:50 PM
Subject: [AAT] Plate Tectonics & hominoid splittings?
India under Asia:
1) OWM/ape split: apes colonized India (low, wet, hot) & became
aquarboreal: vertical waders-climbers along the Tethys Ocean,
2) the Himalaya split colobines (E) & cercopithecines (W),
3) India split lesser (E) & great (W) apes (still predom.aquarboreal):
-- hylobatids along the SE.Asian Ind.Ocean coasts,
-- gr.apes along the Tethys=Med.Sea.
The Mesopotamian Seaway closure c 15 Ma split hominids (W) & pongids
-- pongids along the SE.Asian coastal forests, forcing hylobatids higher into the trees,
-- hominids around the Red & Med.Sea (Graecopith, footprints, Oreopith
etc.) + inland along rivers.
HPG in Red Sea.
E.Afr.Rift fm split Gorilla & HP c 8 Ma:
G followed the rift ->subgenus Praeanthropus Pliocene afarensis
Opening of Red Sea c 5 Ma? = Zanclean flood??:
- Pan fossil subgenus Australopithecus initially followed the E.Afr.coasts ->Pliocene africanus ->Pleist.robustus // E.Afr.apiths,
- Homo followed the S.Asian coasts ->Peistocene shellfish-diving.