Pliocene Research Articles

Fission track age for MT1 tuff bed and paleoenvironment in the Upper Pliocene Mita Formation, Toyama Prefecture, central Japan

富山県富山市八尾町には鮮新統三田層が分布する．この地層は3層の凝灰岩層（OT3，MT1，MT2）を含み，OT3とMT2凝灰岩層の年代は5.2 ± 0.5 Maおよび2.2～2.3 Maと見積もられている．今回，八尾町平林周辺の赤江川流域に分布する，MT1凝灰岩層に対してフィッショントラック法に基づく年代値の推定と，この層準付近から産出する貝形虫と浮遊性有孔虫化石の群集解析を行い，古環境を推定した．その結果，赤江川本流と支流で，3.5 ± 0.2 Maおよび3.4 ± 0.2 Maという年代値が見積もられ，研究結果を統合すると，三田層における暖流系貝化石の初産出層準は3.66～約3.4 Maの範囲にあることが明らかとなった．また，微化石の群集解析から，調査層準下部から上部に向けて，冷温な湾域から温帯性の開放的な浅海域への変遷が認められた．最上部では強い暖流を示す貝形虫化石群集が産出した．

Paleoecological significance of coupling metrics of successful and unsuccessful shell-breaking predation: Examples using Neogene bivalve prey

Traces of durophagous predation on molluscan prey have been used as proxies to reconstruct the nature and intensity of predator–prey interactions in both the fossil record and the modern oceans. Available metrics for the quantification of these interactions have focused either on failed/unsuccessful or successful attacks in isolation. Because predator–prey dynamics and subsequent adaptation depend on both the success as well as the failure of the predator, we propose to combine these two components to increase our ability to reconstruct the dynamics of these relationships in the past. In this study, two bivalve clades, Chione and Varicorbula, from Florida's Plio-Pleistocene fossil record are used to show how the combination of repair frequency and estimated crushing mortality serve as better constraints on interpreting changes in predator–prey interactions as compared to the more limited interpretations when these two metrics are used independently. When used in tandem, the two metrics document an overall predation intensity increase from the upper Pliocene Pinecrest Beds (upper Tamiami Formation to the overlying lower Pleistocene Caloosahatchee, and a decrease in successful attack frequency in the upper Pleistocene Bermont Formations. However, patterns were different in the upper Pleistocene Ft. Thompson Formation: successful attacks increased for Chione and decreased for Varicorbula. In detail, however, the overall dynamics for these two predator–prey systems varied, and they also changed differently throughout the studied interval.

Antelopes (Mammalia, Ruminantia, Bovidae) from the Upper Siwaliks of Tatrot, Pakistan, with description of a new species

New antelope material from the Tatrot type locality of the Tatrot Formation, Upper Siwaliks, northern Pakistan, allows us to recognize four antelopes, i.e., Antilope intermedia sp. nov. Khan and Akhtar, Antilope subtorta Pilgrim, 1937, Antilope cervicapra (Linnaeus, 1758), and Kobus porrecticornis (Lydekker, 1878). Comparisons with A. cervicapra and A. subtorta suggest that A. intermedia sp. nov. is closely related to the black buck A. cervicapra. The new material from Tatrot confirms the idea that antelopes in the Upper Pliocene Tatrot Formation were rather diverse.

Acanthocythereis colini nomen novum for A. reticulata Sciuto, 2014

In Sciuto (2014), a new species, Acanthocythereis reticulata, was described from the Upper Pliocene sediments of NE Sicily and belonging to the family Trachyleberididae Sylvester-Bradley, 1948. Nonetheless, the new species name is preoccupied by A. reticulata Smith, 1978, described from the Danian of Alabama (p. 553, Pl. 5, figs. 5-7). According to the Code of Zoological Nomenclature it is necessary to replace the name of the junior homonym. Therefore, I propose a new name for the species from Capo Milazzo.

Herpetocetus morrowi(Cetacea: Mysticeti), a new species of diminutive baleen whale from the Upper Pliocene (Piacenzian) of California, USA, with observations on the evolution and relationships of the Cetotheriidae

The extinct edentulous mysticete family Cetotheriidae historically has been viewed as a notoriously paraphyletic group, and only recently have rigorous studies been executed to rectify this issue. These problems do not necessarily just stem from lack of phylogenetic analyses, but are in part because of a general lack of complete specimens, poor descriptions of taxa, and long-lived taxonomic instability issues. The fossil mysticete genus Herpetocetus is a poster child of these problems as it is primarily only known from a few relatively incomplete and poorly described specimens. A new species of Herpetocetus from the upper Pliocene of California, Herpetocetus morrowi sp. nov., provides an archetypal model for the genus based on a multitude of well-preserved specimens. These specimens reveal a diminutive mysticete characterized by an elongate rostrum and roughly quadrate cranium. A mosaic of primitive and derived features preserved in this new species underscores its potential value in helping to resolve a number of taxonomic and phylogenetic problems. The occurrence of specimens assignable to juvenile through to mature adult individuals provides a basis for investigating ontogenetic changes. Functional analysis of the unusual craniomandibular anatomy of H. morrowi suggests a limited degree of mandibular gape and an enhanced capacity for longitudinal rotation of the dentary, features that support a hypothesis of suction feeding convergent with that of living grey whales. A phylogenetic analysis provides support for recognition of a redefined and monophyletic Cetotheriidae and Herpetocetinae, and also serves as a basis for evaluating the recent proposal that the pygmy right whale (Caperea marginata) is a living cetothere. Morphological features of Herpetocetus morrowi, including features of the cranium and petrosal, suggest that a number of the purported synapomorphies supporting a Caperea−cetothere grouping are either symplesiomorphies, nonhomologous features, or are highly variable. © 2014 The Linnean Society of London

Source to sink: The development of the latest Messinian to Pliocene–Quaternary Cilicia and Adana Basins and their linkages with the onland Mut Basin, eastern Mediterranean

Abstract Multi-channel seismic reflection profiles show that there is a thick northeast–southwest elongated lobe of uppermost Messinian and Pliocene–Quaternary sediments across the Cilicia Basin extending into the onland Adana Basin. Three prominent seismic markers divide this succession into three subunits. Detailed isopach maps constructed using a dense grid of depth-converted seismic reflection profiles show that these three subunits display distinctive sediment distribution patterns that can be confidently related to eastward deposition from the Goksu River to the west. Subsidence rates calculated at 95 locations within the Cilicia and Adana Basins using OSXBackstrip show that the central axis of the Cilicia–Adana Basin complex is subsiding at a rate of ~ 10–20 mm per year. The subsidence rates sharply decrease both toward the Misis–Kyrenia Fault zone in the south and east and the Turkish continental margin in the west and north to values of 0.10–0.15 mm per year. Subsidence rates were 0.10–0.20 mm per year during the deposition of the middle and upper Pliocene, but decreased to ~ 0.05 mm per year. Sedimentation rates calculated for the three subunits compared to the present-day rate of sedimentation by the Goksu River clearly show that sedimentation in the early Pliocene interval was significantly greater than it is today. The data show that the dramatic subsidence of the Cilicia Basin (~ 2000 m since the Messinian) occurred in synchroneity with the rise of the Mut Basin nestled over the Central Taurus Mountains. The adjacency of the Mut and Cilicia Basins suggests that there must be a common local cause for the uplift of the Mut Basin and the subsidence of the Cilicia Basin. We believe that the rise of the Central Taurus Mountains represents an additional load on the underlying asthenosphere, the isostatic response of which would have caused the subsidence in the Cilicia Basin.

Strong chemistry‐climate feedbacks in the Pliocene

AbstractThe Pliocene epoch was the last sustained interval when global climate was significantly warmer than today but has been difficult to explain fully based on the external forcings from atmospheric carbon dioxide and surface albedo. Here we use an Earth system model to simulate terrestrial ecosystem emissions and atmospheric chemical composition in the mid‐Pliocene (about 3 million years ago) and the preindustrial (~1750s). Tropospheric ozone and aerosol precursors from vegetation and wildfire are ~50% and ~100% higher in the mid‐Pliocene due to the spread of the tropical savanna and deciduous biomes. The chemistry‐climate feedbacks contribute a net global warming that is +30–250% of the carbon dioxide effect and a net aerosol global cooling that masks 15–100% of the carbon dioxide effect. These large vegetation‐mediated ozone and aerosol feedbacks operate on centennial to millennial timescales in the climate system and have not previously been included in paleoclimate sensitivity assessments.

Ostracods of the Upper Pliocene - Pleistocene Punta Mazza succession (NE Sicily) with special focus on the Family Trachyleberididae Sylvester-Bradley, 1948, and description of a new species

The ostracod associations of the Upper Pliocene-Pleistocene sedimentary succession out-cropping at Punta Mazza (Milazzo, Sicily NE) have been investigated. The ostracod fauna is often well-preserved and well-diversified: there 42 species belonging to 24 genera have been found. The association consists almost exclusively of bathyal taxa such as Bythocypris obtusata (Sars), B. bosquetiana (Brady), Henryhowella ex H. profunda Bonaduce et al. group, Quasibuntonia radiatopora (Seguenza), Retibythere (Bathybythere) scaberrima Brady, Pseudocythere caudata Sars and Bythocythere mylaensis Sciuto. Also, the Krithe group is well-represented with Krithe compressa (Seguenza) and K. pernoides (Bornemann). Further taxa such as Cytheropteron testudo Sars are rare. Almost all species, especially those belonging to Trachyleberididae Sylvester-Bradley are described, illustrated and commented on, including a new species, Acanthocythereis reticulata n.sp., found in the lower part of the section in Upper Pliocene sediment, is proposed as new. Finally, a specimen belonging to the genus Quasibuntonia Ruggieri is currently given in open nomenclature.

Upper Pliocene to lower Pleistocene nannofossil datums recognized in the Mera and Minamiasai Formations in the southernmost part of the Boso Peninsula, central Japan

Upper Pliocene to lower Pleistocene nannofossil datums recognized in the Mera and Minamiasai Formations in the southernmost part of the Boso Peninsula, central Japan

Genetic variation in the green anole lizard (Anolis carolinensis) reveals island refugia and a fragmented Florida during the quaternary

The green anole lizard (Anolis carolinensis) is a model organism for behavior and genomics that is native to the southeastern United States. It is currently thought that the ancestors of modern green anoles dispersed to peninsular Florida from Cuba. However, the climatic changes and geological features responsible for the early diversification of A. carolinensis in North America have remained largely unexplored. This is because previous studies (1) differ in their estimates of the divergence times of populations, (2) are based on a single genetic locus or (3) did not test specific hypotheses regarding the geologic and topographic history of Florida. Here we provide a multi-locus study of green anole genetic diversity and find that the Florida peninsula contains a larger number of genetically distinct populations that are more diverse than those on the continental mainland. As a test of the island refugia hypothesis in Pleistocene Florida, we use a coalescent approach to estimate the divergence times of modern green anole lineages. We find that all demographic events occurred during or after the Upper Pliocene and suggest that green anole diversification was driven by population divergence on interglacial island refugia in Florida during the Lower Pleistocene, while the region was often separated from continental North America. When Florida reconnected to the mainland, two separate dispersal events led to the expansion of green anole populations across the Atlantic Seaboard and Gulf Coastal Plain.

Evolution of stomatal and trichome density of the Quercus delavayi complex since the late Miocene

A fossil oak species, Quercus tenuipilosa Q. Hu et Z.K. Zhou, is reported from the upper Pliocene Ciying Formation in Kunming, Yunnan Province, southwestern China. The establishment of this species is based on detailed morphologic and cuticular investigations. The fossil leaves are elliptic, with serrate margins on the apical half. The primary venation is pinnate, and the major secondary venation is craspedodromous. The tertiary veins are opposite or alternate-opposite percurrent with two branches. The stomata are anomocytic, occurring only on the abaxial epidermis. The trichome bases are unicellular or multicellular. The new fossil species shows the closest affinity with the extant Q. delavayi and the late Miocene Q. praedelavayi Y.W. Xing et Z.K. Zhou from the Xiaolongtan Formation of the Yunnan Province. All three species share similar leaf morphology, but differ with respect to trichome base and stomatal densities. Q. tenuipilosa, Q. praedelavayi, and Q. delavayi can be considered to constitute the Q. delavayi complex. Since the late Miocene, a gradual reduction in trichome base density has occurred in this complex. This trend is the opposite of that of precipitation, indicating that increased trichome density is not an adaptation to dry environments. The stomatal density (SD) of the Q. delavayi complex was the highest during the late Miocene, declined in the late Pliocene, and then increased during the present epoch. These values show an inverse relationship with atmospheric CO2 concentrations, suggesting that the SD of the Q. delavayi complex may be a useful proxy for reconstruction of paleo-CO2 concentrations.

A new marine vertebrate assemblage from the Late Neogene Purisima Formation in Central California, part II: Pinnipeds and Cetaceans

ABSTRACT The newly discovered Upper Miocene to Upper Pliocene San Gregorio assemblage of the Purisima Formation in Central California has yielded a diverse collection of 34 marine vertebrate taxa, including eight sharks, two bony fish, three marine birds (described in a previous study), and 21 marine mammals. Pinnipeds include the walrus Dusignathus sp., cf. D. seftoni, the fur seal Callorhinus sp., cf. C. gilmorei, and indeterminate otariid bones. Baleen whales include dwarf mysticetes (Herpetocetus bramblei Whitmore & Barnes, 2008, Herpetocetus sp.), two right whales (cf. Eubalaena sp. 1, cf. Eubalaena sp. 2), at least three balaenopterids (“Balaenoptera” cortesi “var.” portisi Sacco, 1890, cf. Balaenoptera, Balaenopteridae gen. et sp. indet.) and a new species of rorqual (Balaenoptera bertae n. sp.) that exhibits a number of derived features that place it within the genus Balaenoptera. This new species of Balaenoptera is relatively small (estimated 61 cm bizygomatic width) and exhibits a comparatively ...

Mineralogy of Egyptian Bentonitic Clays II: Geologic Origin

AbstractReconstructing the origin of bentonitic clays is often a challenging and rather complicated undertaking, but the analysis of certain predictor clay minerals is proving to be an excellent method to simplify this process. The goal of the present investigation was to use abundance changes of five X-ray diffraction (XRD) predictor minerals to determine the relative contributions of weathering and parent-rock changes to the origin of clay minerals in Egyptian bentonitic clays as the test case. The XRD predictor minerals, selected in an earlier discriminant function analysis of quantitative abundances of 14 minerals, provided a simpler approach to the interpretation of clay-mineral origins because they are the minerals that were most responsible for statistically significant differences among the samples. Changes in mineral composition were basically a function of parent-rock lithology, drainage, and climate interactions. A Paleo-Climate Index (CI; the ratio of coarsely crystalline kaolinite to Fe-rich smectite), and a Parent-Rock Index (PI; the ratio of the illitic phases and quartz abundances to pure smectite) were established to track the paleo-climate and parent-rock changes, respectively. Low CI values indicated that a long, seasonally dry climate prevailed during the Middle Eocene, uppermost Eocene, Lower Miocene, and Upper Pliocene bentonitic clay deposition. Lowermost Upper Eocene and the Middle Miocene bentonitic clays were produced when a wet climate prevailed throughout the year. Moderate to high PI values suggested derivation of the clays from the acidic basement crystalline rocks at Uweinat-Bir Safsaf uplift and Lower Paleogene shales during the Middle Eocene and lowermost Upper Eocene. The youngest Upper Eocene and Lower Miocene materials contained abundant Fe-smectite and low PIs indicating derivation from tholeiitic basalts. Diagenetic and sedimentary segregation modifications were not apparent. Direct evidence for in situ derivation from volcanic precursor materials was lacking in general, but volcanic eruptions were common in the region. The minerals in the Egyptian bentonitic clays formed as weathering products on land and have been transported by north-flowing streams and rivers to the sites of accumulation.

Persistent warmth across the Benguela upwelling system during the Pliocene epoch

A feature of Pliocene climate is the occurrence of “permanent El Niño-like” or “El Padre” conditions in the Pacific Ocean. From the analysis of sediment cores in the modern northern Benguela upwelling, we show that the mean oceanographic state off Southwest Africa during the warm Pliocene epoch was also analogous to that of a persistent Benguela “El Niño”. At present these events occur when massive southward flows of warm and nutrient-poor waters extend along the coasts of Angola and Namibia, with dramatic effects on regional marine ecosystems and rainfall. We propose that the persistent warmth across the Pliocene in the Benguela upwelling ended synchronously with the narrowing of the Indonesian seaway, and the early intensification of the Northern Hemisphere Glaciations around 3.0–3.5 Ma. The emergence of obliquity-related cycles in the Benguela sea surface temperatures (SST) after 3 Ma highlights the development of strengthened links to high latitude orbital forcing. The subsequent evolution of the Benguela upwelling system was characterized by the progressive intensification of the meridional SST gradients, and the emergence of the 100 ky cycle, until the modern mean conditions were set at the end of the Mid Pleistocene transition, around 0.6 Ma. These findings support the notion that the interplay of changes in the depth of the global thermocline, atmospheric circulation and tectonics preconditioned the climate system for the end of the warm Pliocene epoch and the subsequent intensification of the ice ages.

Late cretaceous and cenozoic stratigraphy of the Baikal Rift sediments

The data obtained from long-term field studies in the Baikal Rift area are summarized. A new stratigraphic scheme is developed on the basis of previous stratigraphic research of N.A. Logachev. The new elements of the scheme are (1) the use of regional correlation horizons; (2) recognition of pre-Tankhoi (pre-Late Oligocene) sediments correlated with the Maastrichtian-Early Oligocene deposits of the Baikal Fore-deep; (3) elimination from the scheme of the Khalagai and Anosovka formations and distinction on their basis of the Tagai, Sasa, Osinovka, and Shankhaikha formations; (4) recognition of several weathering crust beds and Neogene paleosols. The “lower Eopleistocene (Upper Pliocene)” red-rock formation of Logachev is subdivided into the following stratigraphic units: the Cretaceous-Paleogene unit characterized by a few finds of Early Oligocene fossils, the Upper Miocene-Lower Pliocene red clay bearing numerous fossil remains, and the Upper Pliocene reddish clay with abundant localities of fossils. The sections examined in the land portion of the Baikal Rift are correlated with bottom sediments of the Baikal depression and are subdivided into three instead of the two commonly accepted large tectonic-lithological-stratigraphic complexes. Stratigraphic studies provide a new insight into the history of the Baikal Rift and into some general questions of the continental rift formation.

Challenges in quantifying Pliocene terrestrial warming revealed by data–model discord

Comparing simulations of key warm periods in Earth history with contemporaneous geological proxy data is a useful approach for evaluating the ability of climate models to simulate warm, high-CO2 climates that are unprecedented in the more recent past. Here we use a global data set of confidence-assessed, proxy-based temperature estimates and biome reconstructions to assess the ability of eight models to simulate warm terrestrial climates of the Pliocene epoch. The Late Pliocene, 3.6–2.6 million years ago, is an accessible geological interval to understand climate processes of a warmer world. We show that model-predicted surface air temperatures reveal a substantial cold bias in the Northern Hemisphere. Particularly strong data–model mismatches in mean annual temperatures (up to 18 °C) exist in northern Russia. Our model sensitivity tests identify insufficient temporal constraints hampering the accurate configuration of model boundary conditions as an important factor impacting on data–model discrepancies. We conclude that to allow a more robust evaluation of the ability of present climate models to predict warm climates, future Pliocene data–model comparison studies should focus on orbitally defined time slices.

Late Miocene threshold response of marine algae to carbon dioxide limitation

Coccolithophores are marine algae that use carbon for calcification and photosynthesis. The long-term adaptation of these and other marine algae to decreasing carbon dioxide levels during the Cenozoic era has resulted in modern algae capable of actively enhancing carbon dioxide at the site of photosynthesis. This enhancement occurs through the transport of dissolved bicarbonate (HCO3(-)) and with the help of enzymes whose expression can be modulated by variable aqueous carbon dioxide concentration, [CO2], in laboratory cultures. Coccolithophores preserve the geological history of this adaptation because the stable carbon and oxygen isotopic compositions of their calcite plates (coccoliths), which are preserved in the fossil record, are sensitive to active carbon uptake and transport by the cell. Here we use a model of cellular carbon fluxes and show that at low [CO2] the increased demand for HCO3(-) at the site of photosynthesis results in a diminished allocation of HCO3(-) to calcification, which is most pronounced in larger cells. This results in a large divergence between the carbon isotopic compositions of small versus large coccoliths only at low [CO2]. Our evaluation of the oxygen and carbon isotope record of size-separated fossil coccoliths reveals that this isotopic divergence first arose during the late Miocene to the earliest Pliocene epoch (about 7-5 million years ago). We interpret this to be a threshold response of the cells' carbon acquisition strategies to decreasing [CO2]. The documented coccolithophore response is synchronous with a global shift in terrestrial vegetation distribution between 8 and 5 Myr ago, which has been interpreted by some studies as a floral response to decreasing partial pressures of carbon dioxide () in the atmosphere. We infer a global decrease in carbon dioxide levels for this time interval that has not yet been identified in the sparse proxy record but is synchronous with global cooling and progressive glaciations.

Hydrocarbon Geology Characteristics and Oil & Gas Resource Potential in the Afghan-Tajik Basin

The Afghan-Tajik Basin is an intermontane depression between the mountain ranges of Gissar and Pamirs, and Jurassic system and Tertiary system are rich in large oil & gas resources. In order to assure sustainable supply of oil & gas from Central Asia, we deeply researched hydrocarbon geology characteristics and resource potentials. The basin belongs to paralic sedimentary environment, and develops 3 sedimentary strata: Jurassic, Cretaceous, and Tertiary. Afghan-Tajik Basin develops 3 main source rocks including clastic rocks of Jurassic, carbonate rocks of Cretaceous and mudstone rocks of Eocene. The basin develops 2 plays: Jurassic-Cretaceous play is gas containing one, and Tertiary play is oil containing one. Plaster stone and salt rock of upper Jurassic are regional cap rocks of Jurassic-Cretaceous gas pool, and creaming mudstone and muddy limestone of Cretaceous and Tertiary are regional or partial cap rocks. Migration and accumulation of hydrocarbon occur in the late Cretaceous and early Pliocene epoch. Afghan-Tajik Basin has larger exploration potentials, and residual resources are 2.4¡Á108t. The potential zones are as follows, south part of basin, oil-gas structures of post-salt, reef limestone of pre-salt, and litho-stratigraphic traps.

Geochemical composition of faecal pellets as an indicator of deposit-feeding strategies in the trace fossilPhymatoderma

Phymatoderma is a branching burrow system consisting of tunnels filled with faecal pellets, and it has been interpreted as a product of a surface deposit-feeding animal. Elemental analyses of Phymatoderma were conducted to reveal the specific feeding mode of its tracemaker, using samples from the Lower Jurassic epicontinental shelf deposits in the Dotternhausen section, southern Germany and from the Upper Pliocene continental slope deposits in the Shioura section, central Japan. Elemental compositions of the pelletal infill of Phymatoderma and its overlying mudstone from the Dotternhausen section show no significant difference, suggesting that the tracemaker was a non-selective deposit feeder. In contrast, elemental compositions of the tuffaceous pellets of Phymatoderma from the Shioura section and its overlying volcanic ash show a difference in trends: CaO is significantly concentrated in the pellets. Because microfossils such as foraminifera and coccoliths are occasionally found in the tuffaceous pellets, CaO accumulation in the pelletal infill indicates the Phymatoderma-producer that lived in the Pliocene slope setting selectively ingested particles with higher biomass of such microorganisms (or ingested microorganisms themselves) when feeding the surface sediments. Although two types of feeding modes of the tracemaker were recognized in Phymatoderma between different bathymetrical settings, each feeding mode seems to be an effective strategy to intake nutrients from the surface sediments and to reflect an adaptation of the tracemaker to the food contents in the surrounding substrate. This study suggests that geochemical composition of faecal pellets of trace fossils can be a useful indicator of grain-selective/non-selective deposit-feeding strategies of ancient animals.

The intensification of the East Asian winter monsoon contributed to the disappearance of Cedrus (Pinaceae) in southwestern China

Climate change during the Quaternary played an important role in the distribution of extant plants. Herein, cone scales of Cedrus (Pinaceae) were uncovered from the Upper Pliocene Sanying Formation, Longmen Village, Yongping County of Yunnan Province in southwestern China. Detailed comparisons show that these fossils all belong to the genus Cedrus (Pinaceae), and a new species is proposed, Cedrus angusta sp. nov. This find expands the known distribution of Cedrus during the Late Pliocene to Yunnan, where the genus no longer exists in natural forests. Based on the analysis of reconstructed Neogene climate data, we suggest that the intensification of the East Asian winter monsoon during the Quaternary may have dramatically increased seasonality and given rise to a much drier winter in Yunnan. Combined with information on Cedrus fossil records and its seed physiology, we conclude that the intensification of a drier climate after the Late Pliocene may have prevented the survival of Cedrus seedlings, leading to the eventual disappearance of Cedrus in western Yunnan. This study indicates that the topography in southwestern China acted as a vital refuge for many plants during the Quaternary, but that other species gradually disappeared due to the intensification of the monsoonal climate.