Palaeogene and Neogene brachyurans of the Amazon basin: a revised first appearance date for primary freshwater crabs (Brachyura, Trichodactylidae)

Crustaceana ◽  
2017 ◽  
Vol 90 (7-10) ◽  
pp. 953-967 ◽  
Author(s):  
Sebastian Klaus ◽  
Célio Magalhães ◽  
Rodolfo Salas-Gismondi ◽  
Martin Gross ◽  
Pierre-Olivier Antoine

We describe claw fragments of fossil primary freshwater crabs from three areas in the Amazon basin, Tarapoto (Early Oligocene) and Contamana (Middle Eocene to early Late Miocene) in Peru, and Eirunepé (Late Miocene) in Brazil. All these fragments most likely belong to the family Trichodactylidae. We show a continuous presence of primary freshwater crabs in proto-Amazonian lowlands from the Middle Eocene to the Late Miocene and can thus shift the earliest appearance date of freshwater-adapted brachyurans into the Eocene, at least in the Neotropics.

2021 ◽  
Vol 118 (37) ◽  
pp. e2105956118
Author(s):  
Kenneth E. Campbell ◽  
Paul B. O’Sullivan ◽  
John G. Fleagle ◽  
Dorien de Vries ◽  
Erik R. Seiffert

The Santa Rosa fossil locality in eastern Perú produced the first Paleogene vertebrate fauna from the Amazon Basin, including the oldest known monkeys from South America. This diverse paleofauna was originally assigned an Eocene age based largely on the stage of evolution of the site’s caviomorph rodents and marsupials. Here, we present detrital zircon dates that indicate that the maximum composite age of Santa Rosa is 29.6 ± 0.08 Ma (Lower Oligocene), although several zircons from Santa Rosa date to the Upper Oligocene. The first appearance datum for Caviomorpha in South America is purported to be the CTA-27 site in the Contamana region of Perú, which is hypothesized to be ∼41 Ma (Middle Eocene) in age. However, the presence of the same caviomorph species and/or genera at both CTA-27 and at Santa Rosa is now difficult to reconcile with a >11-My age difference. To further test the Middle Eocene age estimate for CTA-27, we ran multiple Bayesian tip-dating analyses of Caviomorpha, treating the ages of all Paleogene species from Perú as unknown. These analyses produced mean age estimates for Santa Rosa that closely approximate the maximum 29.6 ± 0.08 Ma composite date provided by detrital zircons, but predict that CTA-27 is much younger than currently thought (∼30 Ma). We conclude that the ∼41 Ma age proposed for CTA-27 is incorrect, and that there are currently no compelling Eocene records of either rodents or primates in the known fossil record of South America.


2014 ◽  
Vol 88 (3) ◽  
pp. 434-443 ◽  
Author(s):  
Donald R. Prothero ◽  
Kenneth E. Campbell ◽  
Brian L. Beatty ◽  
Carl D. Frailey

A new dromomerycine palaeomerycid artiodactyl, Surameryx acrensis new genus new species, from upper Miocene deposits of the Amazon Basin documents the first and only known occurrence of this Northern Hemisphere group in South America. Osteological characters place the new taxon among the earliest known dromomerycine artiodactyls, most similar to Barbouromeryx trigonocorneus, which lived in North America during the early to middle Miocene, 20–16 Ma. Although it has long been assumed that the Great American Biotic Interchange (GABI) began with the closure of the Isthmus of Panama in the late Pliocene, or ca. 3.0–2.5 Ma, the presence of this North American immigrant in Amazonia is further evidence that terrestrial connections between North America and South America through Panama existed as early as the early late Miocene, or ca. 9.5 Ma. This early interchange date was previously indicated by approximately coeval specimens of proboscideans, peccaries, and tapirs in South America and ground sloths in North America. Although palaeomerycids apparently never flourished in South America, proboscideans thrived there until the end of the Pleistocene, and peccaries and tapirs diversified and still live there today.


2001 ◽  
Vol 49 (3) ◽  
pp. I
Author(s):  
Robert S. Hill

The macrofossil record of the plant family Cunoniaceae in Australia is summarised and reviewed where necessary by using detailed studies of the morphology of extant genera. Eleven of the 26 Cunoniaceae genera are represented in the Australian macrofossil record and include leaves and leaf fragments, foliar cuticle and reproductive structures, and range from Late Paleocene to Quaternary in age. Macrofossils show that some genera had a different or more widespread distribution in Australia during the Cenozoic, with two genera (Weinmannia and Codia) having become extinct from the continent. Changes in climate, including increasing cold, frost, dryness, seasonality, or some combination of these, or a reduction in vegetation disturbance regimes (e.g. volcanism, uplifting, landslips), may be implicated in the regional or continental extinctions demonstrated by the macrofossil record. Many extant genera (Schizomeria, Vesselowskya, Callicoma, Ceratopetalum, Acsmithia, Codia) had evolved by the Early Oligocene or earlier (Eucryphia, Late Paleocene; Ceratopetalum, Middle Eocene), perhaps with generic diversification more or less complete by the end of the Early Cenozoic or earlier. A Cretaceous origin of the family is possible, and may account for its widespread distribution on Southern Hemisphere landmasses, although long-distance dispersal events are required to explain some modern geographic disjunctions.


2021 ◽  
Vol 8 ◽  
Author(s):  
C. Montes ◽  
C. A. Silva ◽  
G. A. Bayona ◽  
R. Villamil ◽  
E. Stiles ◽  
...  

Integration of several geologic lines of evidence reveals the prevalence of a lowland trans-Andean portal communicating western Amazonia and the westernmost Andes from at least middle Miocene until Pliocene times. Volcanism and crustal shortening built up relief in the southernmost Central and Eastern Cordilleras of Colombia, closing this lowland gap. Independent lines of evidence consist first, of field mapping in the Tatacoa Desert with a coverage area of ∼381 km2, 1,165 km of geological contact traces, 164 structural data points, and 3D aerial digital mapping models. This map documents the beginning of southward propagation of the southernmost tip of the Eastern Cordillera’s west-verging, fold-and-thrust belt between ∼12.2 and 13.7 Ma. Second, a compilation of new and published detrital zircon geochronology in middle Miocene strata of the Tatacoa Desert shows three distinctive age populations: middle Miocene, middle Eocene, and Jurassic; the first two sourced west of the Central Cordillera, the latter in the Magdalena Valley. Similar populations with the three distinctive peaks have now been recovered in western Amazonian middle Miocene strata. These observations, along with published molecular and fossil fish data, suggest that by Serravallian times (∼13 Ma), the Northern Andes were separated from the Central Andes at ∼3°N by a fluvial system that flowed into the Amazon Basin through the Tatacoa Desert. This paleogeographic configuration would be similar to a Western Andean, or Marañon Portal. Late Miocene flattening of the subducting Nazca slab caused the eastward migration of the Miocene volcanic arc, so that starting at ∼4 Ma, large composite volcanoes were built up along the axis of today's Central Cordillera, closing this lowland Andean portal and altering the drainage patterns to resemble a modern configuration.


2009 ◽  
Vol 28 (1) ◽  
pp. 37-44 ◽  
Author(s):  
R. W. Jones

Abstract. The ages and environments of deposition of the principal mapped units of Barbados, based on foraminiferal and other palaeontological evidence, are discussed, together with the uplift history of the island. The age of the Scotland Formation is demonstrated to be Paleocene to ?early Middle Eocene; that of the Oceanic Formation late Middle Eocene to early Early Miocene; that of the Bissex Hill Formation and Conset Marl late Early to early Late Miocene; and that of the Coral Rock Formation Middle–Late Pleistocene. The environment of deposition of the Scotland Formation is interpreted to be abyssal; that of the Oceanic Formation abyssal to be lower bathyal; that of the Bissex Hill Formation and Conset Marl middle to lower bathyal; and that of the Coral Rock Formation inner neritic. Observed elevation/age relationships imply a mean uplift rate of between 120 m Ma−1 and 220 m Ma−1.


2001 ◽  
Vol 49 (3) ◽  
pp. 301 ◽  
Author(s):  
Richard W. Barnes ◽  
Robert S. Hill ◽  
Jason C. Bradford

The macrofossil record of the plant family Cunoniaceae in Australia is summarised and reviewed where necessary by using detailed studies of the morphology of extant genera. Eleven of the 26 Cunoniaceae genera are represented in the Australian macrofossil record and include leaves and leaf fragments, foliar cuticle and reproductive structures, and range from Late Paleocene to Quaternary in age. Macrofossils show that some genera had a different or more widespread distribution in Australia during the Cenozoic, with two genera (Weinmannia and Codia) having become extinct from the continent. Changes in climate, including increasing cold, frost, dryness, seasonality, or some combination of these, or a reduction in vegetation disturbance regimes (e.g. volcanism, uplifting, landslips), may be implicated in the regional or continental extinctions demonstrated by the macrofossil record. Many extant genera (Schizomeria, Vesselowskya, Callicoma, Ceratopetalum, Acsmithia, Codia) had evolved by the Early Oligocene or earlier (Eucryphia, Late Paleocene; Ceratopetalum, Middle Eocene), perhaps with generic diversification more or less complete by the end of the Early Cenozoic or earlier. A Cretaceous origin of the family is possible, and may account for its widespread distribution on Southern Hemisphere landmasses, although long-distance dispersal events are required to explain some modern geographic disjunctions.


Recent studies that integrate conventional thermobarometry of pelitic mineral assemblages with thermodynamic modeling of garnet zoning reveal complex Tertiary P -T paths for the Greater Himalayan metamorphic sequence in the central Himalaya. Viewed in light of our current understanding of the structural evolution of the Himalaya, these data provide insights into the relations between tectonic and thermal processes during orogenesis. In this paper, we present an interpretive model for tectonothermal evolution of the Greater Himalaya in the central part of the range. This model involves: (1) middle Eocene—early Oligocene burial to depths of more than 30 km during the early stages of collision between India and Asia; (2) early—late Oligocene uplift and cooling; (3) late Oligocene heating and renewed burial synchronous with the early stages of anatectic melting and leucogranite plutonism; (4) latest Oligocene-middle Miocene rapid uplift and continued leucogranite production associated with ramping on the structurally lower Main Central Thrust and tectonic denudation on structurally higher low-angle detachment systems; and (5) middle Miocene—Recent rapid cooling during the final stages of uplift to the surface.


Geosciences ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 34
Author(s):  
Santiago Moliner-Aznar ◽  
Manuel Martín-Martín ◽  
Tomás Rodríguez-Estrella ◽  
Gregorio Romero-Sánchez

The Cenozoic Malaguide Basin from Sierra Espuña (Internal Betic Zone, S Spain) due to the quality of outcropping, areal representation, and continuity in the sedimentation can be considered a key-basin. In the last 30 years, a large number of studies with very different methodological approaches have been done in the area. Models indicate an evolution from passive margin to wedge-top basin from Late Cretaceous to Early Miocene. Sedimentation changes from limestone platforms with scarce terrigenous inputs, during the Paleocene to Early Oligocene, to the deep basin with huge supplies of turbidite sandstones and conglomerates during the Late Oligocene to Early Miocene. The area now appears structured as an antiformal stack with evidence of synsedimentary tectonics. The Cenozoic tectono-sedimentary basin evolution is related to three phases: (1) flexural tectonics during most of the Paleogene times to create the basin; (2) fault and fold compartmentation of the basin with the creation of structural highs and subsiding areas related to blind-fault-propagation folds, deforming the basin from south to north during Late Oligocene to Early Aquitanian times; (3) thin-skin thrusting tectonics when the basin began to be eroded during the Late Aquitanian-Burdigalian. In recent times some works on the geological heritage of the area have been performed trying to diffuse different geological aspects of the sector to the general public. A review of the studies performed and the revisiting of the area allow proposing different key-outcrops to follow the tectono-sedimentary evolution of the Cenozoic basin from this area. Eight sites of geological interest have been selected (Cretaceous-Cenozoic boundary, Paleocene Mula Fm, Lower Eocene Espuña-Valdelaparra Fms, Middle Eocene Malvariche-Cánovas Fms, Lowermost Oligocene As Fm, Upper Oligocene-Lower Aquitanian Bosque Fm, Upper Oligocene-Aquitanian Río Pliego Fm, Burdigalian El Niño Fm) and an evaluation has been performed to obtain four parameters: the scientific value, the educational and touristic potential, and the degradation risk. The firsts three parameters obtained values above 50 being considered of “high” or “very high” interest (“very high” in most of the cases). The last parameter shows always values below 50 indicating a “moderate” or “low” risk of degradation. The obtained values allow us considering the tectono-sedimentary evolution of this basin worthy of being proposed as a geological heritage.


Author(s):  
Ümitcan Erbil ◽  
Aral I. Okay ◽  
Aynur Hakyemez

AbstractLate Cenozoic was a period of large-scale extension in the Aegean. The extension is mainly recorded in the metamorphic core complexes with little data from the sedimentary sequences. The exception is the Thrace Basin in the northern Aegean, which has a continuous record of Middle Eocene to Oligocene marine sedimentation. In the Thrace Basin, the Late Oligocene–Early Miocene was characterized by north-northwest (N25°W) shortening leading to the termination of sedimentation and formation of large-scale folds. We studied the stratigraphy and structure of one of these folds, the Korudağ anticline. The Korudağ anticline has formed in the uppermost Eocene–Lower Oligocene siliciclastic turbidites with Early Oligocene (31.6 Ma zircon U–Pb age) acidic tuff beds. The turbidites are underlain by a thin sequence of Upper Eocene pelagic limestone. The Korudağ anticline is an east-northeast (N65°E) trending fault-propagation fold, 9 km wide and 22 km long and with a subhorizontal fold axis. It is asymmetric with shallowly-dipping northern and steeply-dipping southern limbs. Its geometry indicates about 1 km of shortening in a N25°W direction. The folded strata are unconformably overlain by Middle Miocene continental sandstones, which constrain the age of folding. The Korudağ anticline and other large folds in the Thrace Basin predate the inception of the North Anatolian Fault (NAF) by at least 12 myr. The Late Oligocene–Early Miocene (28–17 Ma) shortening in the Thrace Basin and elsewhere in the Balkans forms an interlude between two extensional periods, and is probably linked to changes in the subduction dynamics along the Hellenic trench.


1998 ◽  
Vol 11 (6) ◽  
pp. 711 ◽  
Author(s):  
Robert S. Hill ◽  
Leonie J. Scriven

A re-investigation of macrofossils previously referred to the extantpodocarpaceous genus Falcatifolium Laubenfels shows thatno records can be sustained. Falcatifolium australisD.R.Greenwood from Middle Eocene sediments in Victoria bears littleresemblance to extant species in the genus and is transferred to the newfossil genus Sigmaphyllum R.S.Hill & L.J.Scriven.Specimens from Early Oligocene sediments in Tasmania previously assigned toFalcatifolium are described as a second species ofSigmaphyllum, S. tasmanensisR.S.Hill & L.J.Scriven, and specimens from mid to late Eocene sediments inTasmania previously assigned to Falcatifolium do notbelong to that genus, although their true generic affinities are uncertain.Dispersed cuticle specimens from Late Eocene–Oligocene sediments inSouth Australia referred to Falcatifolium are notreliable records of the genus and require further investigation. However,Dacrycarpus eocenica D.R.Greenwood, from Middle Eocenesediments in Victoria is transferred to Falcatifolium,and is similar to the extant species F. angustumLaubenfels, which has a leaf morphology unusual for the genus.Falcatifolium eocenica (D.R.Greenwood) R.S.Hill & L.J.Scriven is the only reliable record of the genus in the Australian fossilrecord to date.


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