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Learn about 50 million years of primate evolution during the Pliocene epoch, from their origins in Africa to their spread to the New World and origin of the human species.

Indian summer monsoon (ISM) change under global warming is a serious concern because of its widespread socio‐economic impacts. Under the greenhouse gas (GHG)‐induced near future warming, climate models project a weakened ISM circulation, limiting the rate of monsoon rainfall increase. However, we find that climate models commonly simulate a strengthened ISM circulation in favor of ISM rainfall increase during the mid‐Pliocene that is often considered analogous to the ongoing anthropogenic warming. This enhanced ISM circulation change is physically consistent with a dramatically strong warming over Eastern Eurasia, which strengthened the mid‐upper tropospheric meridional temperature gradient across the ISM region. Sensitivity experiments reveal that such an Eastern Eurasian warming was closely associated with the northern continental greening via local vegetation‐albedo feedback. Our results highlight that the land cover changes, rather than GHG forcing, dominated this regional‐scale warming and resultant regional hydrological cycle in the mid‐Pliocene warm period.

The global flora is thought to contain a large proportion of herbs, and understanding the general spatiotemporal processes that shaped the global distribution of these communities is one of the most difficult issues in biogeography. We explored patterns of world‐wide biogeography in a species‐rich herbaceous group, the paper daisy tribe Gnaphalieae (Asteraceae), based on the hitherto largest taxon sampling, a total of 835 terminal accessions representing 80% of the genera, and encompassing the global geographic range of the tribe, with nuclear internal transcribed spacer (ITS) and external transcribed spacer (ETS) sequences. Biogeographic analyses indicate that Gnaphalieae originated in southern Africa during the Oligocene, followed by repeated migrations into the rest of Africa and the Mediterranean region, with subsequent entries into other continents during various periods starting in the Miocene. Expansions in the late Miocene to Pliocene appear to have been the driving force that shaped the global distribution of the tribe as forests were progressively broken up by the mid‐continent aridification and savannas and grasslands expanded into the interior of the major continents. This pattern of recent colonizations may explain the world‐wide distribution of many other organisms in open ecosystems and it is highlighted here as an emerging pattern in the evolution of the global flora.

Climate models and paleoclimate proxy records indicate that the absence of preserved eastern Mediterranean organic-rich layers preceding mid-Pliocene glaciation is linked to a pan-North African humid period caused by a more northerly African monsoon front relative to subsequent glacials. The vegetation expansion caused by this humid phase might have influenced early hominin dispersal.

Three new equilibrium mid‐Pliocene (MP) simulations are implemented with the Community Climate System Model version 4 (CCSM4) and Community Earth System Model versions 1.2 (CESM1.2) and 2 (CESM2). All simulations are carried out with the same boundary and forcing conditions following the protocol of Pliocene Model Intercomparison Project Phase 2 (PlioMIP2). These simulations reveal amplified MP climate change relative to the preindustrial going from CCSM4 to CESM2, seen in global and polar averages of surface warming, sea ice reduction in both the Arctic and the Antarctic, and weakened Hadley circulation. The enhanced global mean warming arises from enhanced Earth system sensitivity (ESS) to not only CO2 change but also changes in boundary conditions primarily from vegetation and ice sheets. ESS is amplified by up to 70% in CCSM4 and up to 100% in CESM1.2 and CESM2 relative to the equilibrium climate sensitivity of respective models. Simulations disagree on several climate metrics. Different from CCSM4, both CESM1.2 and CESM2 show reduction of cloud cover, and weakened Walker circulation accompanied by an El Niño‐like mean state of the tropical Pacific in MP simulations relative to the preindustrial. This El Niño‐like mean state is consistent with paleo‐observational sea surface temperatures, suggesting an improvement upon CCSM4. The performances of MP simulations are assessed with a new compilation of observational MP sea surface temperature. The model‐data comparison suggests that CCSM4 is not sensitivity enough to the MP forcings, but CESM2 is likely too sensitive, especially in the tropics. Plain Language Summary Our knowledge of past climate evolves with both new paleo‐observations and advancements in modeling past climates. Using the mid‐Pliocene (MP, 3.205 million years ago) as an example, we demonstrate how to implement geological reconstructions of past topography, bathymetry, and vegetation distribution in Earth system models (ESMs); how to initialize these experiments; and, finally, the new knowledge learnt from simulations with three consecutive versions of the ESMs from the same model lineage. In our simulations, the MP climate warms substantially more than the estimated amount of warming that only consider changes in CO2 radiative forcing. The simulated MP climate features strongly amplified polar warmth, massive loss of Arctic and Antarctic summer sea ice, and weakened Northern Hemispheric cell of the Hadley circulation. Interestingly, two newer versions of ESMs are more sensitive to not only CO2 changes but also changes in biome range and ice sheets than the earlier version. Paleo‐observations suggest that MP global warming is underestimated by the previous versions of models but may be overestimated by the latest version. Key Points PlioMIP2 simulations are completed with Earth System Models from the NCAR family: CCSM4, CESM1, and CESM2 Simulated mid‐Pliocene climate by CESM2 features greater changes in many climate metrics than simulations by previous versions CESM1 and CESM2 match paleo‐observations better than CCSM4, yet CESM2 likely overestimates the Earth System Sensitivity

The evolution of Sahel summer rainfall in the context of global warming is a severe socio-economic concern because of its widespread influences on local agriculture, water resource management, food security, infrastructure planning, and ecosystems. Based on the mid-Pliocene simulations from the Pliocene Model Intercomparison Project Phase 2 and the historical simulations and shared socio-economic pathway 5–8.5 experiments from the Coupled Model Intercomparison Project phase 6, the present study contrasts the Sahel summer rainfall changes between the past mid-Pliocene and near future global warming climates. The results show that the Western African summer monsoon (WASM) circulation, closely linked with the Sahel summer rainfall change, tends to strengthen in both the past and future global warming climates, but the monsoonal circulation strengthening is much more intense in the past warm period than in the projected warm future. This causes that the multi-model ensemble (MME) mean increase ratio of Sahel summer rainfall in the past warming climate is about twice to three times larger than that in the future warming climate for the same increase of global mean surface temperature (the regional rainfall increase ratio in the MME mean: about 19.6% per one degree Celsius of global warming in the mid-Pliocene simulations versus about 7.7% per one degree Celsius of global warming in the SSP5-8.5 future projections). Such a striking discrepancy in the regional circulation and hydrological cycle changes is mainly attributed to a dramatically stronger warming over the Canadian Archipelago and Greenland during the mid-Pliocene warm period relative to the projected near future. The more significant northern high-latitude warming during the mid-Pliocene enhances the meridional temperature gradient between the extratropical and tropical regions, which could induce an excessive northward shift of the Intertropical Convergence Zone and a stronger WASM, and thus result in a more intense hydrological cycle around the Sahel region. Our results highlight that besides the global mean temperature increase, meridional warming patterns are also essential for the changes of WASM and regional hydrological cycle in a warmer world. Implications for projecting the regional monsoon and hydrological cycle changes at longer time scales than in the near future are discussed.

The specific name velunensis is established to encompass porcupine remains ( Hystrix Linnæus, 1758) recovered from the Pliocene site of Węże 1 in southern Poland. The studied specimen was previously assigned either to H. primigenia (Wagner, 1848) or H. depereti Sen, 2001, however it can be distinguished from these species and other fossil Hystricidae by its distinct occlusal morphology, most importantly the presence of an anterolingual flexus dissecting the anteroloph of P4. Hystrix velunensis sp. nov. was probably closely related to H. primigenia and H. depereti. A previously undescribed specimen from the nearby site of Węże 2 most probably belongs to H. refossa Gervais, 1852b, which would be the first known occurrence of this species in Poland.

In this paper, the holotype (and hitherto single) specimen (part and counterpart) of Chelydra strausi Schmidt, 1966, from the Late Pliocene of the former clay pit of Willershausen (Lower Saxony, northwestern Germany) is revised for the first time. The main result of the present study is that it belongs to the extinct genus Chelydropsis Peters, 1858, where it is preliminary assigned to Ch. aff. nopcsai (Szalai, 1934).

Aim The Hengduan Mountains (HDM) of southwest China is a biodiversity hotspot and harbours one of the world's richest temperate floras. However, the origin and evolution of its biota remain largely unresolved. Here we explore the impact of mountain uplift on the diversification process of biodiversity in this hotspot using alpine bamboos. Location The HDM region, southwest China. Taxon Alpine bamboos. Methods We used ddRAD‐seq data from the most complete sampling of alpine bamboos undertaken to date (79% of the species diversity), to investigate their evolutionary history. The ancestral area of these bamboos was reconstructed using a time‐calibrated phylogeny in BioGeoBEARS and diversification rates were inferred using BAMM analyses. In addition, the impact of mountain uplift on the divergence of alpine bamboos was evaluated using trait‐dependent models of diversification. Results The alpine bamboos were strongly supported as monophyletic, and the relationships within them were robustly resolved. Fargesia was found to be polyphyletic and Yushania was resolved as monophyletic. Alpine bamboos originated outside the HDM region during the late Miocene, and spread to this region in the Pliocene, undergoing a significant acceleration in net diversification, which is temporally congruent with the orogeny. The speciation rate increased with altitude and a high diversification rate, estimated to be 0.75 species per million years, was detected for alpine bamboos distributed in high elevations. Main Conclusions Our study demonstrates that heterogeneous mountain habitats and geographical isolation of alpine bamboos, which have limited dispersal ability, are important drivers for their rapid diversification. This study also highlights the power of complementary analyses in revealing the link between species diversification and past geological changes.

Understanding ice sheet behaviour in the geological past is essential for evaluating the role of the cryosphere in the climate system and for projecting rates and magnitudes of sea level rise in future warming scenarios 1 – 4 . Although both geological data 5 – 7 and ice sheet models 3 , 8 indicate that marine-based sectors of the East Antarctic Ice Sheet were unstable during Pliocene warm intervals, the ice sheet dynamics during late Pleistocene interglacial intervals are highly uncertain 3 , 9 , 10 . Here we provide evidence from marine sedimentological and geochemical records for ice margin retreat or thinning in the vicinity of the Wilkes Subglacial Basin of East Antarctica during warm late Pleistocene interglacial intervals. The most extreme changes in sediment provenance, recording changes in the locus of glacial erosion, occurred during marine isotope stages 5, 9, and 11, when Antarctic air temperatures 11 were at least two degrees Celsius warmer than pre-industrial temperatures for 2,500 years or more. Hence, our study indicates a close link between extended Antarctic warmth and ice loss from the Wilkes Subglacial Basin, providing ice-proximal data to support a contribution to sea level from a reduced East Antarctic Ice Sheet during warm interglacial intervals. While the behaviour of other regions of the East Antarctic Ice Sheet remains to be assessed, it appears that modest future warming may be sufficient to cause ice loss from the Wilkes Subglacial Basin. Studies of an Antarctic marine sediment core suggest that the East Antarctic Ice Sheet retreated in the vicinity of the Wilkes Subglacial Basin during extended warm periods of the late Pleistocene, when temperatures were similar to those predicted to occur within this century.