scholarly journals Immigration dynamics of tropical and subtropical Southeast Asian limestone karst floras

2022 ◽  
Vol 289 (1966) ◽  
Author(s):  
Xiao-Qian Li ◽  
Xiao-Guo Xiang ◽  
Qiang Zhang ◽  
Florian Jabbour ◽  
Rosa del C. Ortiz ◽  
...  
Keyword(s):  
Middle Miocene ◽  
Acid Soil ◽  
Southeast Asian ◽  
Late Eocene ◽  
Ex Situ ◽  
Early Pleistocene ◽  
Divergence Times ◽  
Niche Shift ◽  
Ancestral States ◽  
Two Peaks

Ex situ origins and dispersal of taxa have played important roles in the assembly of island-like biodiversity hotspots. Insular limestone karsts in Southeast Asia are hotspots of biodiversity and endemism, but the immigration processes of their unique floras are still poorly known. Here, we used Gesneriaceae as a proxy to investigate the immigration dynamics of tropical and subtropical Southeast Asian karst floras. We present the most comprehensive phylogenetic analysis of the Old World gesneriads to date based on twelve loci. By estimating divergence times and reconstructing ancestral states (habitat, soil type and range), we found that immigration into subtropical Southeast Asian karst floras first occurred in the Early Miocene, with two peaks in the Early–Middle Miocene and the Pliocene–Early Pleistocene, whereas immigration into tropical Southeast Asian karsts initiated in the Late Eocene, with two peaks in the Late Oligocene and the Late Miocene. We also discover that Southeast Asian karst biodiversity comprises immigrant pre-adapted lineages and descendants from local acid soil ancestors, although niche shift from acid soil to karst in tropical Southeast Asian islands was lacking. This study advances our understanding of the historical assembly of Southeast Asian karst floras.

Middle Miocene recovery of Caribbean reef corals: New data from the Tamana Formation, Trinidad

2001 ◽  
Vol 75 (3) ◽  
pp. 513-526 ◽  
Author(s):  
Kenneth G. Johnson
Keyword(s):  
Middle Miocene ◽  
New Records ◽  
Early Miocene ◽  
Early Pleistocene ◽  
Reef Corals ◽  
Rigorous Description ◽  
Caribbean Coral Reef ◽  
The Caribbean ◽  
Stratigraphic Ranges ◽  
Biotic Change

Caribbean coral reef communities were restructured by episodes of accelerated biotic change during the late Oligocene/early Miocene and the late Pliocene/early Pleistocene. However, rigorous description of the effects of rapid biotic change is problematic because preservation and exposure of coral-bearing deposits is not consistent in all stratigraphic intervals. In the Caribbean, early and middle Miocene exposures are more rare than late Miocene and Pliocene exposures. One exception is the late early to early middle Miocene Tamana Formation of Trinidad, and old and new collections from this unit were studied to determine the timing of recovery after the Oligocene/Miocene transition. A total of 41 species of zooxanthellate corals were recovered from the unit, including 21 new records. Within these assemblages, species first occurrences outnumber species last occurrences by a factor of four (31 first occurrences and eight last occurrences). The extension of the stratigraphic ranges of species previously first recorded in Pliocene sediments has reduced an apparent Pliocene pulse of origination, indicating that the Pliocene/Pleistocene transition was largely a result of accelerated extinction against a background of near-constant origination. The fact that few species last occur in the Tamana fauna indicates that the Oligocene/Miocene transition was complete by the end of the early Miocene.

scholarly journals Petrography of the Siwalik sandstones, Amlekhganj-Suparitar area, central Nepal Himalaya

2003 ◽  
Vol 28 ◽  
Author(s):  
Naresh Kazi Tamrakar ◽  
Shuichiro Yokota ◽  
Suresh Das Shrestha
Keyword(s):  
Middle Miocene ◽  
Foreland Basin ◽  
Early Pleistocene ◽  
Nepal Himalaya ◽  
Central Nepal ◽  
Present Study Area ◽  
Mean Grain Size ◽  
Siwalik Group ◽  
Variation Trends ◽  
The Himalaya

Middle Miocene to early Pleistocene sedimentary sequence deposited in the foreland basin of the Himalaya is represented by the Siwalik Group. In the present study area the Siwalik Group extends in a NW-SE direction and well-exposed. Forty­four sandstone samples were studied for texture, fabric and composition in order to assess their petrographic properties and variation trends of these properties in stratigraphic levels. Sandstones were classified into sublitharenite, subarkose, lithic arenite, arkosic arenite and feldspathic graywacke and further thirteen sub-clans. Mean grain size (M) and Trask sorting coefficient (So) increase up-section. Recalculated quartz, matrix, modified maturity index (MMI), total cement (Ct), cement versus matrix index (CMI) and ratio of strong cement over total cement ((Cfc/Cs)/Ct) also increase, whilst packing proximity (PP), packing density (PD) and consolidation factor (Pcc) decrease up-section showing distinct trends, and therefore, these properties are promising in recognizing the older sandstones from the younger ones.

Grossplots: a Method for Estimating the Temperature State of the Earth and of Australia, Cretaceous to Middle Miocene

1997 ◽  
Vol 45 (3) ◽  
pp. 359 ◽  
Author(s):  
L. A. Frakes
Keyword(s):  
Middle Miocene ◽  
Global Climate ◽  
Interval Data ◽  
Late Eocene ◽  
Space Distribution ◽  
Mean Annual Temperature ◽  
The North ◽  
Early Oligocene ◽  
Time Space ◽  
Temperature State

Grossplots are compilations of globally distributed palaeotemperature data onto latitude versus age plots, which are then contoured. The results specifically show the distribution of temperature over the globe and its variations over the Cretaceous to Middle Miocene interval. Data for continents and oceans are plotted separately in this investigation, and each such grossplot is in accord with the known climate changes of this time. The general scarcity of quantitative palaeotemperature information for Australia can be rectified by deriving, from the global continental grossplot, the relationship between mean annual temperature and latitude. When these are applied to the latitude band progressively occupied by Australia, the following observations can be made: (1) during the Early Cretaceous, the south-east of the continent was subjected to freezing wintertime temperatures; (2) peak warming of northern Australia was attained in the Turonian–Santonian, but this was followed by cooling later in the Cretaceous; (3) Early Tertiary warming until the Late Eocene particularly affected the northern half of the continent, but this region then underwent the most severe cooling in the Early Oligocene; (4) subsequently, the whole of the continent cooled uniformly from conditions only slightly warmer than at present. Despite Australia’s equatorward march, the Late Cretaceous to Palaeocene climates of the continent have been influenced more effectively by changes in the global climate state. However, global cooling since the Eocene has been less effective than drift in controlling the warming climate of Australia. The time–space distribution of precipitation over Australia is estimated from the global relationship between terrestrial temperature and rainfall. The Eocene experienced the heaviest rainfall (> 1560 mm year-1, in the north only), and the Eocene to Middle Miocene experienced moderately high rates (> 500 mm year-1 in the northern three-quarters of the continent). Tertiary brown coals in southern regions were formed in proximity to areas of high rainfall. Continentwide low rates (< 500 mm year-1; semi-arid) are suggested for the Cretaceous, except for wet conditions in the north during the Albian–Santonian and the Late Maastrichtian. Estimates of precipitation are subject to factors such as continentality and location of moisture sources, which cannot be evaluated at present.

Distinguishing tectonic versus climatic forcing on landscape evolution: An example from SE Tibetan Plateau

2020 ◽  
Vol 133 (1-2) ◽  
pp. 233-242 ◽  
Author(s):  
Fangbin Liu ◽  
Martin Danišík ◽  
Dewen Zheng ◽  
Kerry Gallagher ◽  
Junsheng Nie
Keyword(s):  
Tibetan Plateau ◽  
Middle Miocene ◽  
Asian Summer Monsoon ◽  
Late Eocene ◽  
Crustal Shortening ◽  
Lateral Extrusion ◽  
Granite Belt ◽  
Cooling Phase ◽  
Forcing Mechanisms ◽  
Exhumation History

Abstract Distinguishing climate from tectonic forcing in shaping the Earth’s surface has been a long-standing issue in the Earth sciences. Great debate exists regarding when and how the SE Tibetan Plateau achieved its current low-relief topography, and both lateral extrusion and lower crust flow have been proposed as the dominant mechanism. Reconstruction of the exhumation history of the SE Tibetan Plateau is key to understanding these formation processes and resolving the significance of different forcing mechanisms. Here we report zircon and apatite (U-Th)/He ages from steep transects across the Lincang granite belt of the SE Tibetan Plateau. Our results reveal a two-stage exhumation history during the Cenozoic with rapid cooling phases in the late Eocene and the middle Miocene. In the late Eocene, the climate was generally dry and there is plenty of evidence for increased extrusion and upper crustal shortening. We suggest tectonic processes are responsible for the first inferred cooling. In contrast, the Asian summer monsoon precipitation increased during the middle Miocene, and we posit the middle Miocene cooling phase records a phase of rapid river incision triggered by the intensified precipitation and associated fault movements. The results are consistent with recent paleo-altimetry work in this region suggesting that the present-day topography of the SE Tibetan Plateau had been largely constructed by the late Eocene. Together, these data suggest that extrusion and/or upper crustal shortening setup the first order topography of the SE Tibetan Plateau, which was then modified by climate-triggered fluvial incision and feedbacks initiated in the middle Miocene.

Evolutionary adaptation and geographic spread of the Cenozoic buccinid genus Lirabuccinum in the North Pacific

2003 ◽  
Vol 77 (5) ◽  
pp. 863-872 ◽  
Author(s):  
Kazutaka Amano ◽  
Geerat J. Vermeij
Keyword(s):  
North Pacific ◽  
Middle Miocene ◽  
Eastern Pacific ◽  
Early Pleistocene ◽  
Northwestern Pacific ◽  
The North ◽  
Early Oligocene ◽  
Rocky Bottom ◽  
Late Middle Miocene ◽  
The Western Pacific

The Early Oligocene to Recent genus Lirabuccinum Vermeij, 1991, is a North Pacific clade of rocky-bottom predatory buccinid gastropods. A re-examination of all available material from eastern Asia and comparison of this material with western American species leads us to recognize four northwestern Pacific species: L. fuscolabiatum (Smith, 1875) from the Pliocene to Recent; L. japonicum (Yokoyama, 1926) from the Pliocene and Early Pleistocene; L. branneri (Clark and Arnold, 1923) from the early Middle Miocene, also known from the Oligocene in the eastern Pacific; and Lirabuccinum sp. from the late Middle Miocene. The genus originated in the eastern Pacific and subsequently spread to the western Pacific by late Early Miocene to early Middle Miocene time. Lirabuccinum exemplifies a common pattern among rocky-bottom North Pacific gastropods in that the early species have a thick, internally strongly ribbed or denticulate outer lip. As they adapted to the colder boreal realm during the Pliocene and Pleistocene, Lirabuccinum and such other clades as Nucella, Ceratostoma, and Ocinebrellus (all Muricidae) evolved thinner, less heavily reinforced outer lips.

Remarks on the age of Dominican amber

2019 ◽  
Vol 2 (3) ◽  
pp. 236-240 ◽  
Author(s):  
MANUEL A. ITURRALDE-VINENT ◽  
ROSS D.E. MACPHEE
Keyword(s):  
Dominican Republic ◽  
Analytical Approach ◽  
Late Eocene ◽  
Early Pleistocene ◽  
High Quality ◽  
Lower Miocene ◽  
Dominican Amber ◽  
Geological Age ◽  
Best Fit ◽  
Age Estimates

Amber from the Dominican Republic is famous for the high quality, frequency, and diversity of organic fossils found as inclusions in this mineral (Grimaldi, 1996; Poinar & Poinar, 1999). However, its geological age of origin remains a continuing source of controversy. Over the years a wide variety of age estimates have been made for occurrences of Dominican amber, ranging from Cretaceous (Brouwer & Brouwer, 1982) to Late Eocene (Lambert et al., 1985) to pre-Lower Miocene (Baroni-Urbani & Saunders, 1982). Some authors have also favored a spread of ages that covers much of the Cenozoic (e.g., 40 or 45 Ma to 15 Ma; Poinar & Poinar, 1999). Iturralde-Vinent & MacPhee (1996) attempted to resolve discrepancies in age assignments by taking a multi-pronged analytical approach which yielded a best-fit estimate of mid-Miocene age (20–15 Ma). This estimate has been widely accepted and additionally corroborated by new studies (Iturralde-Vinent, 2001; Ortega-Ariza et al., 2015). However, Braga et al. (2012) have challenged the assessment of Iturralde-Vinent & MacPhee (1996) by arguing for a Pliocene–early Pleistocene date for the amber-bearing Yanigua Formation. Here we address the sources of disagreement and suggest a solution.

scholarly journals The Late Eocene – Recent <i>Bradleya johnsoni</i> Benson lineage (Crustacea, Ostracoda) in the Central Equatorial Pacific

1988 ◽  
Vol 7 (2) ◽  
pp. 187-199 ◽  
Author(s):  
P. Lewis Steineck ◽  
David Yozzo
Keyword(s):  
Middle Miocene ◽  
Late Eocene ◽  
Equatorial Pacific ◽  
General Increase ◽  
Reticular Pattern ◽  
Lower Oligocene ◽  
Upper Oligocene ◽  
Central Equatorial Pacific ◽  
Stratigraphic Ranges ◽  
Direct Ancestor

Abstract. Three stratigraphically successive species of Bradleya Hornibrook, 1952 from abyssal sediments of the central equatorial Pacific (Leg 85, Deep Sea Drilling Project) form an unbranching evolutionary sequence designated as the B. johnsoni Benson lineage. These taxa are B. sp. 1 (Lower Oligocene), B. johnsoni (Upper Oligocene – Middle Miocene) and B. thomasi n. sp. (Upper Miocene – Recent). A shared synapomorphic character, the posterior bridge complex, establishes the kinship of these species. Their stratigraphic ranges and a traceable series of changes in the organisation and mass of the reticulum are consistent with the hypothesis of direct ancestor/descendant relationships between them. Bradleya johnsoni is distinguished from B. sp. 1 by the appearance of new primary muri in the posteroventral region and by a general increase in reticular mass. In B. thomasi, the overall reticular pattern is maintained but it becomes more delicate and less rectilinear. Each species of this lineage shows similar variation in the posteroventral reticulum.

scholarly journals Systematics and Phylogeography of The Non-Ethiopian Speckled-Pelage Brush-Furred Rats (Lophuromys Flavopunctatus Group) Inferred From Integrative Genetics and Morphometry

2021 ◽  
Author(s):  
Kenneth Onditi ◽  
Julian Kerbis Peterhans ◽  
Chen Zhongzheng ◽  
Terrence Demos ◽  
Josef Bryja ◽  
...  
Keyword(s):  
Taxonomic Diversity ◽  
Morphological Characters ◽  
Early Pleistocene ◽  
Divergence Times ◽  
Mtdna Phylogeny ◽  
Divergence Dating ◽  
History Of ◽  
Primary Groups ◽  
Bayesian Phylogenetic Inference ◽  
Dispersal Events

Abstract Background: The speckled-pelage brush-furred rats (Lophuromys flavopunctatus group) has been difficult to define given conflicting genetic, morphological, and distributional records that combine to obscure meaningful accounts of its taxonomic diversity. In this study, we inferred the systematics, phylogeography, and evolutionary history of the L. flavopunctatus group using maximum likelihood and Bayesian phylogenetic inference, divergence times, historical biogeographic reconstruction, and morphometric discriminant tests. We compiled comprehensive datasets of three loci (two mitochondrial [mtDNA] and one nuclear) and two morphometric datasets (linear and geometric) from across the known range of the genus Lophuromys.Results: The mtDNA phylogeny supported the division of the genus Lophuromys into three primary groups with nearly equidistant pairwise differentiation: one group corresponding to the subgenus Kivumys (Kivumys group) and two groups corresponding to the subgenus Lophuromys (L. sikapusi group and L. flavopunctatus group). The L. flavopunctatus group comprised the speckled-pelage brush-furred Lophuromys endemic to Ethiopia (Ethiopian L. flavopunctatus members [ETHFLAVO]) and the non-Ethiopian ones (non-Ethiopian L. flavopunctatus members [NONETHFLAVO]) in deeply nested relationships. There were distinctly geographically structured mtDNA clades among the NONETHFLAVO, which were incongruous with the nuclear tree where several clades were unresolved. The morphometric datasets did not systematically assign samples to meaningful taxonomic units or agreed with the mtDNA clades. The divergence dating and ancestral range reconstructions showed the NONETHFLAVO colonized the current ranges over two independent dispersal events out of Ethiopia in the early Pleistocene.Conclusion: The phylogenetic associations and divergence times of the L. flavopunctatus group conform to demonstrated hypotheses surrounding the paleoclimatic and ecosystem refugium impacts on the evolutionary radiation of rodents dependent on stably humid conditions in the East Africa region. The overlap in craniodental variation between distinct mtDNA clades among the NONETHFLAVO suggests unraveling underlying ecomorphological drivers is key to reconciling taxonomically informative morphological characters. The genus Lophuromys requires a taxonomic reassessment based on extensive genomic evidence to elucidate the patterns and impacts of genetic isolation at clade contact zones.

scholarly journals Late Cenozoic palaeogeography of the eastern North Sea Basin: climatic vs tectonic forcing of basin margin uplift and deltaic progradation

2002 ◽  
Vol 49 ◽  
pp. 145-170
Author(s):  
Mads Huuse
Keyword(s):  
North Sea ◽  
Middle Miocene ◽  
Late Eocene ◽  
Middle Pleistocene ◽  
Tectonic Events ◽  
Erosional Unloading ◽  
Southern Norway ◽  
Uplift And Erosion ◽  
Basin Margin ◽  
Passive Model

The late Eocene to middle Pleistocene development of the eastern North Sea Basin is described by a series of palaeogeographic maps. The maps are based on published information integrated with recent investigations of seismic and well data from the eastern North Sea. The maps provide overviews of the basin geometry at late Eocene, late Oligocene, middle Miocene, late Miocene, late Pliocene and middle Pleistocene time. In post-Eocene time, the eastern and central North Sea Basin was progressively filled by large deltas, which built out from the eastern basin margin. These deltas were fed by ancient rivers from southern Norway (late Paleocene-Oligocene and Pliocene), southern Norway and Sweden (early Miocene), the Baltic region (middle Miocene-early Pleistocene), and finally by rivers flowing northward through the northwest European lowland (middle Pleistocene). It is argued that the Cenozoic evolution of the eastern North Sea Basin may be explained by a ‘self-perpetuating’ passive model. This model involves isostatic uplift of source areas due to erosional unloading of a relief generated by early Palaeogene uplift. The erosional unloading accelerated at the Eocene/Oligocene transition, in the middle Miocene and in the Plio-Pleistocene corresponding to periods of global climatic cooling and long-term eustatic lowering as indicated by δ18O records. The passive model diminishes the need for hypothetical Neogene tectonic events, although the influence of tectonic events cannot be excluded. Previous estimates of Neogene uplift and erosion of the northeastern Danish North Sea of the order of 500–1000 m do not agree with seismic geometries or with the regional palaeogeographic development. This indicates that previous estimates of Neogene uplift and erosion of the northeastern Danish North Sea may be several hundred metres too high.

Sign in / Sign up

Export Citation Format

Share Document