...
Post A Reply
my profile
|
directory
login
|
register
|
search
|
faq
|
forum home
»
EgyptSearch Forums
»
Deshret
»
Some interesting articles
» Post A Reply
Post A Reply
Login Name:
Password:
Message Icon:
Message:
HTML is not enabled.
UBB Code is enabled.
[QUOTE]Originally posted by DD'eDeN: [QB] Primates in Asia moved to Africa The recent paper in Science now suggests that the Simia (Anthropoidea) came from S-Asia to Africa (which doesnıt explain how Strepsirhini/lemurs got in Madagascar). They were probably monkeylike insecti-frugivores, possibly 1 or 2 kg. Itıs not impossible [per MVerhaegen) that, as Guiseppe Sera suggested some 90 years ago, the early Simia (vs tarsiers & Strepsirhini) already had some aquatic features (IHO of ears, nose, vagina, kidneys & spleen IIRC), e.g. for surface-swimming (e.g. to reach other trees in swamps e.g. during the flooded season? cf sloths?). I think that Saadanius c 30 Ma (found near Mekka, in mangroves then) had elongated nasal bones, nostrils very close to each other, "tenting" nostrils & large paranasal maxillary sinuses for frequent surface-swimming. Did the early Simia reach Africa floating?? (The NWM-LCA seem to have rafted to S.America.) Have galago ancestors (Strepsirhini) always lived in Africa? Of course, there were a lot of parallelisms in primates lineages, as always, but the Simia seem to have followed a somewhat different evolutionary path than the prosimians. --- Oligocene primates from China reveal divergence between African and Asian primate evolution Xijun Ni, Qiang Li, Lüzhou Li & K Christopher Beard 2016 Science 352:673-7 doi 10.1126/science.aaf2107 Climate filters dominant species The transition between the Eo- & Oligocene was marked by distinct cooling. Because primate spp are particularly susceptible to cold, this change in climate drove a retraction of primates globally. After this transition, anthropoid primates were dominant in Afro-Arabia, but little has been known about primate reestablishment in Asia. Ni cs describe 10 previously unknown primates found in Yunnan Province, that show that primates took a different path in Asia. Instead of anthropoids, strepsirrhine (lemur-like) primates were dominant. It is still unknown whether this difference was due to the environment or chance. Abstract Profound environmental & faunal changes are associated with climatic deterioration during the Eocene-Oligocene transition (EOT) c 34 Ma. Reconstructing how Asian primates responded to the EOT has been hindered by a sparse record of Oligocene primates in Asia. Here, we report the discovery of a diverse primate fauna from the early Oligocene of S-China. In marked contrast to Afro-Arabian Oligocene primate faunas, this Asian fauna is dominated by strepsirhines. There appears to be a strong break between Paleogene & Neogene Asian anthropoid assemblages. Asian & Afro-Arabian primate faunas responded differently to EOT climatic deterioration: the EOT functioned as a critical evolutionary filter, constraining the subsequent course of primate evolution across the Old World. ____ 9.5.16 New Oligocene primates from China highlight key evolutionary period Chinese Academy of Sciences Headquarters Profound environmental & faunal changes are associated with climatic deterioration during the Eocene-Oligocene transition (EOT) c 34 Ma. Primates are among the most environmentally sensitive of all mammals. Reconstructing how Asian primates responded to the EOT has been hindered by a sparse record of Oligocene primates on that continent. NI Xijun cs (Science 6.5.16) reported the discovery of a diverse primate fauna from the early-Oligocene of S-China. In marked contrast to Afro-Arabian Oligocene primate faunas, this Asian fauna is dominated by strepsirhines. There appears to be a strong break between Paleogene & Neogene Asian anthropoid assemblages. Asian & Afro-Arabian primate faunas responded differently to EOT climatic deterioration: the EOT functioned as a critical evolutionary filter, constraining the subsequent course of primate evolution across the Old World. This study provides a deeper understanding of a pivotal moment in the evolution of primates. These newly discovered fossil primates were collected via careful excavation & screen-washing at Lijiawa (upper part of Caijiachong Fm, Yuezhou Basin). The Lijiawa fossil site has yielded >10 mammal taxa that indicate an early-Oligocene age. Researchers described 10 previously unknown primates, represented by fossil teeth, jaws & a few other bones, helping to fill the gap in the record of Asian primate evolution. Anthropoids (monkeys & apes) originated in Asia, with their earliest fossils dating from 45 Ma. Only later, c 38 Ma, did some anthropoids migrate to Africa. It was on that continent 200 ka that humans arose. The transition between the Eo- & Oligocene was marked by distinct cooling. This change in climate drove a retraction of primates globally. Comparing the composition of the early-Oligocene primate faunas from Yunnan & Pakistan with later Eocene Asian primates known from China, Myanmar & Thailand, researchers revealed that surviving the EOT entailed a high degree of taxonomic & ecological selectivity. - Later Eocene primate assemblages in China, Myanmar & Thailand tend to be dominated (in taxonomic richness & numerical abundance) by stem anthropoids belonging to the families Eosimiidae & Amphipithecidae. - In stark contrast, only 1 of the 6 primates known from the early Oligocene of Yunnan is an anthropoid. - 3 of 5 primate spp documented from the late early Oligocene of Pakistan are anthropoids, but even in this case, the anthropoid taxa known from Pakistan differ from their contemporary African relatives in being relatively small-bodied. However, late-Eocene-early-Oligocene primates from Afro-Arabia show a very different pattern of taxonomic selectivity in response to the EOT. - There, very few strepsirhines (none of which were large) survived the EOT, - but anthropoids diversified both taxonomically & ecologically, and became dominant in Afro-Arabian regions. NI Xijun: "The EOT functioned as a critical evolutionary filter during the evolutionary history of primates. - Before the Tps dropped, Asia's primates were dominated by anthropoids. - Afterward, they were dominated by lemur-like primates, with the monkey-like ones decimated². The EOT climatic deterioration may be the reason why apes & people emerged in Africa, even though anthropoids first appeared in Asia. Co-author Christopher Beard : "We had a lot of evidence previously that the earliest anthropoids originated in Asia. The EOT climate crisis virtually wiped out Asian anthropoids, so the only place where they could evolve to become later monkeys, apes & humans was Africa." Dynamic changes to the Asian physical environment during the interval spanning the EOT included - progressive retreat of the Para-Tethys Sea from C-Asia, - continued uplift of the Tibetan-Himalayan orogen & - opening of the South China Sea. Co-author LI Qiang: "Africa was not immune to global climatic changes across the EOT, but it did not experience the dramatic tectonic & paleo-geographic alterations that characterized Asia at this time. It is tempting to attribute the different patterns of turnover in Asian & African primate faunas across the EOT to local changes in vegetation & paleo-environment, but current evidence is not sufficient to rule out the possibility that random processes may also play a substantial role". Beard: "We have so many primates from the Oligocene at this particular site in China, because it was located far enough to the south that it remained warm enough during that cold, dry time that primates could still survive there." They crowded into the limited space that remained available to them. Like most of today's primates, they were tropical tree-dwellers. The lone anthropoid in the group, a small, monkey-like primate named Bahinia banyueae, probably resembled some of today's smaller S.American monkeys such as marmosets, and its teeth suggest its diet was mainly fruits & insects. MV @ AAT: There was a single source once of all primates (the primate LCA), but there might have been parallel evolutions in some prosimian or earlier groups (some omomyids//paromomyids, some strepsi-//haplorrhines etc.), esp. on different continents (e.g. Africa//Asia//Madagascar?), but I have no good insight in these fossils. My impression FWIW, the primate LCA was possibly a rel.slow end-branch grasping arboreal (cf nails instead of claws), feeding on flowers, nectar & fruits & later insects. The early haplorrhines seem to have become faster hunters on flying insects (cf strongly overlapping visual fields). The early simians became more frugivorous again? Haplorrhines = tarsiers + simians=anthropoids: - Tarsiers = SE.Asia. - Simia = New + Old World simians: -- NW monkeys probably crossed the Atlantic 40-30 Ma (then much narrower). -- OW simians (OWMs + hominoids) probably originated in Africa-Arabia, but the simian LCA might have come from S.Asia 40 Ma or more. Strepsirrhines today: Madagascar, Africa, S.Asia. [/QB][/QUOTE]
Instant Graemlins
Instant UBB Code™
What is UBB Code™?
Options
Disable Graemlins in this post.
*** Click here to review this topic. ***
Contact Us
|
EgyptSearch!
(c) 2015 EgyptSearch.com
Powered by UBB.classic™ 6.7.3