60 results on '"Larry G. Marshall"'
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2. Evolution of the Neotropical Cenozoic Land Mammal Fauna in Its Geochronologic, Stratigraphic, and Tectonic Context
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Larry G. Marshall and Thierry Sempere
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- 2018
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3. River behavior on megafans and potential influences on diversification and distribution of aquatic organisms
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John G. Lundberg, M. Justin Wilkinson, and Larry G. Marshall
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Hydrology ,River sediment ,Ecology ,Geology ,Earth-Surface Processes ,Aquatic organisms - Abstract
Megafans are partial cones of river sediment usually laid down by a single switching river, characterized by areas on the order of 103–105 km2, smooth plains, and slopes of
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- 2006
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4. Age and stratigraphic reassessment of the fossil-bearing Laguna Umayo red mudstone unit, SE Peru, from regional stratigraphy, fossil record, and paleomagnetism
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Jean-Yves Crochet, Bernard Sigé, Thierry Sempere, Robert F. Butler, and Larry G. Marshall
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Paleomagnetism ,biology ,Paleontology ,Biostratigraphy ,biology.organism_classification ,Cretaceous ,Space and Planetary Science ,Chulpasia ,Phanerozoic ,Cenozoic ,Paleogene ,Geology ,Magnetostratigraphy - Abstract
The thick red mudstone unit that crops out at Laguna Umayo (Puno department, southern Peru), here referred as LURMU, has yielded in different levels a fossil assemblage with plants and vertebrates (including mammals). On the basis of charophytes, the unit was initially assigned to the Vilquechico Formation (Maastrichtian-Danian), of regional extension, and the dinosaurian structure of egg fragments was interpreted as consistent with that age. Revision of the regional stratigraphy leads to reassignment of this unit to the Lower Munani Formation (Early Tertiary). Mammals from the LU-3 and Chulpas levels present affinities with forms from the Upper Paleocene of South America (Patagonia, Brazil). A bunodont marsupial, Chulpasia, is evidence for chronologic proximity to a transantarctic interchange with Australia at the end of the Paleocene. Furthermore, magnetostratigraphy of the LURMU reveals a single reverse polarity zone of 300 m thickness. Because of the new stratigraphic and paleomammalogic data, this long reverse polarity zone is likely correlative to Chron 26r (early Late Paleocene) or Chron 24r (latest Paleocene–earliest Eocene), or, less likely, to Chron 29r (latest Cretaceous–earliest Paleocene). The arguments previously invoked in favor of a Cretaceous age (charophytes, dinosaurian eggs) are critically evaluated, and correlation to Chron 24r is favored.
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- 2004
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5. Middle Maastrichtian vertebrates (fishes, amphibians, dinosaurs and other reptiles, mammals) from Pajcha Pata (Bolivia). Biostratigraphic, palaeoecologic and palaeobiogeographic implications
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Henri Cappetta, Mireille Gayet, Larry G. Marshall, François J. Meunier, Thierry Sempere, and Jean-Claude Rage
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Andinichthyidae ,Lepisosteidae ,biology ,Ecology ,Fauna ,Paleontology ,Vertebrate ,Oceanography ,Osteoglossiformes ,biology.organism_classification ,Cretaceous ,Characidae ,biology.animal ,Latidae ,Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes - Abstract
The Pajcha Pata fossil locality in south central Bolivia, in the upper part of the Lower Member of the El Molino Formation, is the first late Cretaceous fauna in South America which has yielded, in addition to some invertebrates and plants, all kinds of vertebrates except birds, but including dinosaurs and mammals. Its middle Maastrichtian age, indicated by geochronologic data, is consistent with the fauna, including the marine ichthyofauna. The vertebrate fossils reported here come from the main fossiliferous level which includes terrestrial, freshwater and marine taxa: vertebrates, Mammalia (both tribosphenic and non-tribosphenic therians), Theropoda (Coelurosauria and Sauropoda), Crocodylia, Squamata (Serpentes), Chelonia, Amphibia (Anura, Gymnophiona, Caudata) and fish (Dipnoi, Teleostei, Actinopteri, Cladistia, Chondrostei); invertebrates (Gastropoda, Bryozoa) and plants (charophytes). Amongst these taxa are the earliest records of some fish, Amphibia and tribosphenic Mammalia in South America and/or in the world. The fish concerned are: Polypteriformes (Latinopollia suarezi), Siluriformes of the family Andinichthyidae (Andinichthys) and two new families, Osteoglossiformes of the subfamily Heterotidinae (Osteoglossidae), Perciformes of the family Latidae, Dipnoi of the family Lepidosirenidae (Lepidosiren cf. paradoxa). The Amphibia concerned are: indeterminate Gymnophiona, Noterpetontidae (Noterpeton bolivianum). Pajcha Pata is the only known locality in South America with both non-tribosphenic and tribosphenic therian mammals. The depositional environment was probably estuarian or lagoonal as indicated by a mixed continental, freshwater, and marine fauna. Comparison of this local fauna with faunas of the same age at localities belonging to the same proximal part of the El Molino basin on one hand, and with others belonging to the distal part on the other hand, shows that the two continental areas seem to have their own endemic freshwater fish fauna (except the Characidae and the Lepisosteidae, known in all levels of Bolivia). However, these two areas have the same marine taxa. This implies some influence of the sea in the whole basin. Calculated temperatures of the marine waters range from 13 to 17° for a latitute of about 22°S, implying a southern Pacific upwelling. The El Molino Basin could have been also connected with the open sea through present-day Argentina and not only Venezuela as thought until now.
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- 2001
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6. Stratigraphy and chronology of Upper Cretaceous–lower Paleogene strata in Bolivia and northwest Argentina
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D. R. Richards, Robert F. Butler, Thierry Sempere, Larry G. Marshall, Warren D. Sharp, and Carl C. Swisher
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Paleontology ,Geology ,Sequence stratigraphy ,Chronostratigraphy ,Paleogene ,Unconformity ,Foreland basin ,Magnetostratigraphy ,Cretaceous ,Marine transgression - Abstract
Integration of sequence stratigraphy, magnetostratigraphy, Ar/Ar dating, and paleontology considerably advances knowledge of the Late Cretaceous–early Paleogene chronostratigraphy and tectonic evolution of Bolivia and adjacent areas. The partly restricted marine El Molino Formation spans the Maastrichtian and Danian (°73–60.0 Ma). Deposition of the alluvial to lacustrine Santa Lucia Formation occurred between 60.0 and 58.2 Ma. The widespread erosional unconformity at the base of the Cayara Formation is 58.2 Ma. This unconformity separates the Upper Puca and Corocoro supersequences in Bolivia, and is thus coeval with the Zuni-Tejas sequence boundary of North America. The thick overlying Potoco and Camargo formations represent a late Paleocene–Oligocene foreland fill. The onset of shortening along the Pacific margin at °89 Ma initially produced rifting in the distal foreland. Santonian–Campanian eastward-onlapping deposits indicate subsequent waning of tectonic activity along the margin. Significant tectonism and magmatism resumed along the margin at °73 Ma and produced an abrupt increase in subsidence rate and other related phenomena in the basin. Subsidence was maximum between °71 and °66 Ma. Due to the early Maastrichtian global sea-level high, marine waters ingressed from the northwest into this underfilled basin. Subsidence decreased during the Late Maastrichtian and was low during the Danian. It increased again in the latest Danian, for which a slight transgression is recorded, and peaked in the early Selandian. Tectonism between 59.5 and 58.2 Ma produced a variety of deformational and sedimentary effects in the basin and correlates with the end of emplacement of the Coastal batholith. The subsequent 58.2 Ma major unconformity marks the onset of continental foreland basin development, which extended into Andean Bolivia during the late Paleocene–Oligocene interval. This basin underwent internal deformation as early as Eocene time in the Altiplano and Cordillera Oriental. These early structures, previously assigned to the late Oligocene–early Miocene orogeny, probably accommodated observed tectonic rotations in the Eocene–Oligocene.
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- 1997
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7. Chronostratigraphy of the mammal-bearing Paleocene of South America
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Larry G. Marshall, Thierry Sempéré, and Robert F. Butler
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Paleontology ,Fauna ,North American land mammal age ,Geology ,Sequence stratigraphy ,Mammal ,Structural basin ,Chronostratigraphy ,Cenozoic ,Magnetostratigraphy ,Earth-Surface Processes - Abstract
Land mammal faunas of Paleocene age in the southern Andean basin of Bolivia and NW Argentina are calibrated by regional sequence stratigraphy and magnetostratigraphy. The local fauna from Tiupampa in Bolivia is ~59.0 Ma, and is thus early Late Paleocene in age. Taxa from the lower part of the Lumbrera Formation in NW Argentina (long regarded as Early Eocene) are between ~58.0–55.5 Ma, and thus Late Paleocene in age. A reassessment of the ages of local faunas from the Rio Chico Formation in the San Jorge basin, Patagonia, southern Argentina, shows that the local fauna from the Banco Negro Inferior is ~60.0 Ma, making this the most ancient Cenozoic mammal fauna in South America. Critical reevaluation of the Itaborai fauna and associated geology in SE Brazil favors the interpretation that it accumulated during a sea-level lowstand between ~58.2-56.5 Ma. All known South American Paleocene land mammal faunas are thus between 60.0 and 55.5 Ma (i.e. Late Paleocene) and are here assigned to the Riochican Land Mammal Age, with four subages (from oldest to youngest: Peligrian, Tiupampian, Itaboraian, Riochican s.s.). Based on the fact that notable taxonomic reorganization of Riochican faunas begins ~58.2 Ma, an Early (Peligrian, Tiupampian; 60.0–58.2 Ma) and Late (Itaboraian, Riochican s.s.; ~58.2-55.5 Ma) subdivision for this land mammal age is formally recognized. An interchange event for continental taxa between North and South America is identified between 58.2 and 56.5 Ma, which correlates with a sea-level lowstand and was probably enhanced by a major tectonic event beginning ~59.5 Ma that uplifted the Andean margin.
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- 1997
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8. The Terror Birds of South America
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Larry G. Marshall
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Panama ,Paleontology ,Multidisciplinary ,Geography ,Extinction ,Land bridge ,Biogeography ,Paleoecology ,Biostratigraphy ,Neogene ,Predation - Published
- 1994
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9. Late Oligocene-Early Miocene compressional tectosedimentary episode and associated land-mammal faunas in the Andes of central Chile and adjacent Argentina (32–37°s)
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Thierry Semper, Larry G. Marshall, Estanislao Godoy, and Sergio Rivano
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010506 paleontology ,geography ,geography.geographical_feature_category ,Volcanic arc ,Tectonic phase ,Sedimentary basin ,010502 geochemistry & geophysics ,Neogene ,01 natural sciences ,Paleontology ,Geophysics ,Sedimentary rock ,Thrust fault ,Paleogene ,Foreland basin ,Geology ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
A reassessment of the geologic and land-mammal fossil evidence used in attribution of a tectosedimentary episode in the Andes between 32 and 37°S to the Middle Eocene “Incaic tectonic phase” of Peru indicates that the episode occurred during Late Oligocene-Early Miocene times(~ 27-20 Ma). From west to east, three structural domains are recognized for this time span in the study area: a volcanic arc (Chile); a thin-skinned, E-verging fold-thrust belt (Cordillera Principal, Chile-Argentina border strip); and a foreland basin (Argentina). Initiation of thrusting in the Cordillera Principal fold-thrust belt produced the coeval initiation of sedimentation in the foreland basin of adjacent Argentina. This onset of foreland deposition postdates strata bearing a Divisaderan Land Mammal Age fauna (i.e. ~ 35-30 Ma) and is marked at ~ 36°30′S by the base of the “Rodados Lustrosos” conglomerates, which are conformably overlain by sedimentary rocks containing a Deseadan Land Mammal Age fauna (i.e. ~ 29-21 Ma). Geologic relationships between the thick volcanic Abanico (Coya-Machali) and Farellones formations also demonstrate that this tectosedimentary episode practically ended at ~ 20 Ma at least in the volcanic arc, and was therefore roughly coeval with the major tectonic crisis (~ 27-19 Ma) known in northwestern Andean Bolivia some 1500 km to the north. This strongly suggests that a long, outstanding tectonic upheaval affected at least an extended 12–37°S segment of the Andean margin of South America during Late Oligocene and Early Miocene times.
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- 1994
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10. Megafan Environments in Northern South America and their Impact on Amazon Neogene Aquatic Ecosystems
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Mikhail H. Kreslavsky, Larry G. Marshall, John G. Lundberg, and M. Justin Wilkinson
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Hydrology ,Amazon rainforest ,Ecology ,Aquatic ecosystem ,Neogene ,Geology - Published
- 2011
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11. Enigmatic Caudata (amphibia) from the upper cretaceous of gondwana
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Larry G. Marshall, Jean-Claude Rage, and Mireille Gayet
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Gondwana ,Paleontology ,Sister group ,Space and Planetary Science ,media_common.quotation_subject ,Mesozoic ,Biostratigraphy ,Phyletic gradualism ,Geology ,Cretaceous ,Caudata ,media_common - Abstract
All living and fossil salamanders known till now are primarily Laurasian and have amphicoelous or opisthocoelous vertebrae. But Cretaceous salamanders from Gondwanan continents (South America and Africa) have procoelous vertebrae. One of them, from the Maastrichtian of Bolivia, is here described as Noterpeton bolivianum gen. and sp. nov. and it is referred to a family of its own, Noterpetontidae fam. nov. It is suggested that the procoelous Gondwanan forms could represent the sister group of all the other salamanders, but no detailed phyletic study can be undertaken on the basis of the available material.
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- 1993
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12. Relationships of the dog‐like marsupials, deltatheroidans and early tribosphenic mammals
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Larry G. Marshall and Zofia Kielan-Jaworowska
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Paraphyly ,Tribosphenida ,Eutheria ,biology ,Paleontology ,Zoology ,Metatheria ,biology.organism_classification ,Deltatheroida ,Ecology, Evolution, Behavior and Systematics ,Cretaceous ,Cladistics ,Protocone - Abstract
A cladistic analysis of the major groups of early metatherian mammals shows that the Deltatheroida and South American dog-like Borhyaenoidea are closely related and are placed in a new supercohort Deltatheralia. while all other metatherians are placed in the supercohort Marsupialia. A reassessment of Early Cretaceous mammals with tribosphenic molars shows that metatherians and eutherians apparently evolved independently from a peramuran-like ancestor, and an entoconid. distinctly basined talonid and large protocone were acquired separately in each group. Consequently. the Tribosphenida (sensu McKenna) is apparently paraphyletic. Aegialodontia are regarded as structurally ancestral to Metatheria but not Eutheria. The known fossil record supports the view that differentation of the stocks which gave rise to metatherians and eutherians apparently occurred in Late Jurassic or Early Cretaceous time.
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- 1992
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13. Alcidedorbignya inopinata(Mammalia: Pantodonta) from the Early Paleocene of Bolivia: phylogenetic and paleobiogeographic implications
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Larry G. Marshall and Christian de Muizon
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Synapomorphy ,Paleontology ,Phylogenetic tree ,biology ,Paracone ,Genus ,Alcidedorbignya ,Metacone ,biology.organism_classification ,Pantodonta ,Geology - Abstract
Alcidedorbignya inopinataMuizon and Marshall is a primitive pantodont from the Early Paleocene of Tiupampa, Department of Cochabamba, in the “Cordillera Oriental” of south-central Bolivia. It is known by almost complete upper and lower dentitions, which are described in detail. The occurrence of abundant juvenile specimens allows a study of tooth replacement. The molars ofAlcidedorbignya inopinataare primitive for a pantodont but they show the characteristic synapomorphy of the group, which is the presence of a V-shaped ectoloph of P3-4. However, the paracone and the metacone ofA. inopinataare separated at their bases, a feature absent in the Bemalambdidae andHarpyodus, which have connate to semi-connate paracone and metacone. Because of this character,A. inopinata, although the oldest, is not the most primitive pantodont. However,A. inopinata, as in bemalambdids andHarpyodus, does not have a mesostyle on M1-2/ or a strongly V-shaped centrocrista, which are found in all other pantodonts. For this reason,Alcidedorbignya inopinatais removed from the Pantolambdidae (which are too specialized) and referred to the new monotypic family Alcidedorbignyidae. The family Wangliidae Van Valen, 1988, is not accepted here and the genusWangliais regarded as a junior synonym ofHarpyodus; the latter includes the two speciesH. eurosandH. decorus.Analysis of pantodont origins leads to the conclusion that didelphodontines constitute the best potential sister-group; however, no synapomorphy could be found to substantiate this hypothesis.Alcidedorbignya inopinatais the first pantodont known from a southern continent and, being the oldest, it raises a discussion on the paleobiogeographic history of the group.
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- 1992
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14. Geochronology of the mammal-bearing late Cenozoic on the northern Altiplano, Bolivia
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G.H Curtis, Carl C. Swisher, Larry G. Marshall, R Hoffstetter, and A. Lavenu
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geography ,geography.geographical_feature_category ,Geology ,Late Miocene ,Sanidine ,Unconformity ,Volcanic rock ,Paleontology ,Igneous rock ,Absolute dating ,Geochronology ,Cenozoic ,Earth-Surface Processes - Abstract
Samples of seven tuff or ignimbrite units associated with known land mammal faunas of late Miocene and Pliocene age were collected from 17 localities on the northern Altiplano of western Bolivia. Mineral separates dated by the classic 40K-40Ar technique (35 dates) and by single crystal laser fusion (SCLF) 40Ar/39Ar analysis (84 dates) indicate the following preferred ages based on SCLF 40Ar/39Ar dates on sanidine for six of these units: Ulloma Tuff, 10.35±0.06 Ma; Callapa Tuff, 9.03±0.07 Ma; Toba 76, 5.348±0.003 Ma; Ayo Ayo Tuff, 2.896±0.006 Ma; Perez Ignimbrite, 2.815±0.005 Ma; and Chijini Tuff, 2.650±0.012 Ma. Land mammal faunas of early Huayquerian age are bracketed below by the Callapa Tuff (9.0 Ma) and above the base of the Cerke Formation (7.6 Ma); faunas of Montehermosan age are bracketed below by the Toba 76 and Cota Cota Tuffs (ca. 5.4 Ma), and above by the Ayo Ayo and Chijini Tuffs (ca. 2.8 Ma) of the Umala and La Paz Formations, respectively; and faunas of Ensenadan and Lujanian age occur in rocks younger than 1.6 Ma. Hiatuses identified by the absence of late Huayquerian and Chapadmalalan-Uquian faunas correlate with unconformities which are interpreted as deformation phases: the first with Q3 (8.0-5.5 Ma) and the second with Q4 (2.8-1.6 Ma) of the Quechua Orogeny.
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- 1992
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15. Miocene Deposits in the Amazonian Foreland Basin
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Larry G. Marshall and John G. Lundberg
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Background information ,Paleontology ,Multidisciplinary ,Amazon rainforest ,Amazonian ,Sedimentary rock ,Acre ,Palaeogeography ,Foreland basin ,Geology - Abstract
In their report, Matti E. Rasanen et al. state that there is a tidal origin for the sedimentary sequences they studied in the western Amazon region (1). Their interpretation of these sequences in Acre, Brazil, as tidal, on the basis of a relatively small data set, implies the existence of a marine connection between the Caribbean Sea and the southern Atlantic Ocean. Background information and earlier work suggests that this conclusion is not the best explanation of the sediments in Acre. The sedimentary history and paleogeography of this area are more complex than Rasanen et al. or S. David Webb, in his Perspective (2), suggest.
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- 1996
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16. Late Cretaceous and Paleocene Pan-American Interchanges of Continental Vertebrates
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Mireille Gayet, Jean-Claude Rage, Thierry Sempere, and Larry G. Marshall
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- 1996
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17. Paleomagnetic determinations of vertical-axis tectonic rotations from Late Cretaceous and Paleocene strata of Bolivia
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Larry G. Marshall, D. R. Richards, Thierry Sempere, and Robert F. Butler
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Tectonics ,Paleomagnetism ,Paleontology ,Orocline ,Vertical axis ,Geology ,Orogeny ,Thickening ,Clockwise ,Cretaceous - Abstract
Structural development of the Altiplano during the past 10 m.y. involved crustal thickening and enhanced curvature of the central Andes. Oroclinal bending of 30° explains reasonably the pattern of vertical-axis rotations observed from units with ages 10 to 30 Ma. New paleomagnetic data from Late Cretaceous through Paleocene strata of southeastern Peru and the Eastern Cordillera of Bolivia document rotations that are also counterclockwise on the north limb of the orocline and clockwise on the south limb. However, the rotations of units with ages 30 to 70 Ma are more variable; nearby areas have undergone differential vertical-axis rotations of up to 60° . These larger rotations that have affected 30–70 Ma units in the central Andes may represent (1) local rotations during late Oligocene to present orogeny, (2) local rotations during Eocene orogeny, and/or (3) oroclinal bending during Eocene orogency.
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- 1995
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18. 40K-40Ar age calibration of Late Miocene-Pliocene mammal-bearing Huayquerias and Tunuyan formations, Mendoza Province, Argentina
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Garniss H. Curtis, Robert E. Drake, and Larry G. Marshall
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0106 biological sciences ,010506 paleontology ,Bearing (mechanical) ,Calibration (statistics) ,Paleontology ,Late Miocene ,010603 evolutionary biology ,01 natural sciences ,law.invention ,law ,Mammal ,Geology ,0105 earth and related environmental sciences - Abstract
Mineral separates of five tuffs interbedded in the mammal-bearing Huayquerías and Tunuyán formations in Mendoza Province, west-central Argentina, were dated by the 40K-40Ar method. At the locality of Rio Seco Ultima Aguada on the east side the Meseta Guadal three biotite concentrates of a tuff from a level that apparently corresponds to the very top of the Huayquerias Formation (or less probably to the very bottom of the Tunuyan Formation, sensu Dessanti, 1946) yielded an average age of 5.8 ± 0.1 Ma. The boundary between the Huayquerias Formation (namesake and type formation and fauna of the Huayquerian Land Mammal Age) and the Tunuyan Formation (which contains a Montehermosan age fauna at this locality) is thus about 5.8 Ma. At the locality of Rio Seco de la Salada on the west side of the Meseta Guadal, glass concentrates from two tuffs in the upper part of the Tunuyan Formation yielded ages of 2.6 ± 0.1 and 2.4 ± 0.3 Ma, respectively (the latter date is from a tuff located 90 m stratigraphically above the former). These dates indicate that the rocks and faunas from the upper part of the Tunuyan Formation are of Chapadmalalan (i.e., 2.8 to 2.5 Ma) and Uquian (i.e., 2.5 to 1.5 Ma) age. The faunas from the lower and middle parts of the Tunuyan Formation on the east side of the Meseta Guadal are apparently all of Montehermosan age (i.e., ca. 6.0 to 2.8 Ma).
- Published
- 1986
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19. Variation between groups in evolutionary rates: a statistical test of significance
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David M. Raup and Larry G. Marshall
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0106 biological sciences ,010506 paleontology ,Extinction ,Ecology ,Range (biology) ,Paleontology ,Evolution of mammals ,Biology ,010603 evolutionary biology ,01 natural sciences ,Taxon ,Evolutionary biology ,Mammal ,Taxonomic rank ,General Agricultural and Biological Sciences ,Origination ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences ,Statistical hypothesis testing - Abstract
The statistical significance of differences in evolutionary rate between major taxonomic groups is evaluated using conventional chi-square techniques on stratigraphic range data. Romer's (1966) compilation of stratigraphic ranges of fossil mammals is used to determine whether orders differ significantly from each other in generic origination and extinction rates. The evolutionary histories of 2180 genera (primarily Cenozoic in age) are analyzed. Chi-square testing shows that significantly high or low (P ≥ 0.99) extinction or origination occurs in 15% of the testable cases. Significantly high or low evolutionary turnover in a taxon (orders in this case) we term taxotely. Significantly high turnover rate is equivalent to Simpson's tachytely and significantly low turnover is equivalent to his bradytely.In the mammal data set, taxotely is largely attributable to the influence of South American endemics. Some of the effect is interpreted as an artifact of biases in the fossil record (or its study) and some is attributed to real biological aspects of mammalian evolution.
- Published
- 1980
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20. A model for paleobiogeography of South American cricetine rodents
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Larry G. Marshall
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0106 biological sciences ,010506 paleontology ,geography ,geography.geographical_feature_category ,Ecology ,biology ,Land bridge ,Paleontology ,myr ,Disjunct ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Archaeology ,Biological dispersal ,Foothills ,Glacial period ,General Agricultural and Biological Sciences ,Oryzomyini ,Ecology, Evolution, Behavior and Systematics ,Sea level ,Geology ,0105 earth and related environmental sciences - Abstract
A model for the paleobiogeographic history of South American cricetine rodents is proposed based on new and/or recently published fossil, geological, paleobotanical and radioisotope data. Cricetine rodents of the tribe Sigmodontini evolved in North America before 7.0 Myr BP. They got to South America by waif dispersal across the Bolivar Trough marine barrier from Central America during a world wide drop in sea level (the “Messinian Low”) between 7.0 and 5.0 Myr BP. The basal stock was probably a sylvan (forest) form, from which evolved pastoral (grazing) forms in the savanna-grassland area of Venezuela, Colombia and the Guianas. The pastoral forms in the northern savanna-grassland area were restricted there until about 3.5 Myr BP. At that time there occurred the first glaciation in South America and consonant with glacial advance was a retraction of forest habitats and an expansion of savanna-grassland habitats. At that time the pastoral forms were able to disperse southward through a savanna-grassland corridor along the eastern foothills of the Andes and spread throughout the previously disjunct savanna-grasslands of Bolivia and Argentina. Cricetines are first recorded as fossil in the Monte Hermoso Fm. of Argentina which is about 3.5 Myr BP in age. The Panamanian land bridge came into existence about 3.0 Myr BP as indicated by the beginning of a major interchange of terrestrial faunas between the Americas, which was well underway by 2.7 Myr BP.
- Published
- 1979
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21. Magnetic Polarity Stratigraphy and 40K-40Ar Dating of Late Miocene and Early Pliocene Continental Deposits, Catamarca Province, NW Argentina
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Garniss H. Curtis, Larry G. Marshall, Robert F. Butler, and Robert E. Drake
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Sedimentary depositional environment ,Paleomagnetism ,Paleontology ,Stratigraphy ,Geologic time scale ,Geology ,Radiometric dating ,Tertiary ,Late Miocene ,Cenozoic - Abstract
Magnetostratigraphic and $^{40}K -^{40}Ar$ data on a 2300 m thick sequence of continental sediments at Puerta de Corral Quemado in Catamarca Province, NW Argentina permit calibration of land mammal faunas of late Tertiary (Huayquerian and Montehermosan) age. The sequence represents (from oldest to youngest) the Chiquimil A, Araucanense, and Corral Quemado Formations. Paleomagnetic samples were collected from 99 stratigraphic levels. Strong-field thermomagnetic and isothermal remanent magnetization experiments indicate that the dominant ferrimagnetic mineral is magnetite. Progressive alternating-field (AF) and themal demagnetization of the natural remanent magnetism (NRM) demonstrates that AF demagnetization to 20 mT peak field is sufficient to isolate the primary NRM which is of depositional origin. The resulting paleomagnetic data provide a well-defined magnetic polarity zonation, although sampling is less dense in the upper half of the section. $^{40}K-^{40}Ar$ data obtained from mineral separates of fo...
- Published
- 1984
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22. A new argyrolagoid (Mammalia: Marsupialia) from the middle Miocene of Bolivia
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Larry G. Marshall and A Carlos Villarroel
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0106 biological sciences ,010506 paleontology ,Paleontology ,Geography ,010603 evolutionary biology ,01 natural sciences ,0105 earth and related environmental sciences - Abstract
A new argyrolagoid marsupial, Hondalagus altiplanensis n. gen., n. sp., from the middle Miocene (Santacrucian–Friasian) age locality of Quebrada Honda in southernmost Bolivia represents the smallest and most specialized member of the family Argyrolagidae known. The lower molars are hypselodont and lack vertical grooves labially and lingually, and M4 is greatly reduced relative to M3. In overall size and structure, H. altiplanensis compares best with Microtragulus catamarcensis (Kraglievich, 1931) from rocks of late Miocene (Huayquerian) age in northwest Argentina. Hondalagus altiplanensis demonstrates that the adaptive radiation of argyrolagoids was much greater than previously envisioned, and that generic differentiation of known taxa occurred no later than early–middle Miocene time in South America.
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- 1988
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23. Caenolestidae Trouessart, 1898, And Palaeothentidae Sinclair, 1906 2214
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Richard H. Tedford and Larry G. Marshall
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Geography - Published
- 1978
- Full Text
- View/download PDF
24. A New Genus of Caroloameghiniinae (Marsupialia: Didelphoidea: Didelphidae) from the Paleocene of Brazil
- Author
-
Larry G. Marshall
- Subjects
Geography ,Ecology ,Genus ,Genetics ,Zoology ,Animal Science and Zoology ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation - Published
- 1982
- Full Text
- View/download PDF
25. Geochronology of Type Uquian (Late Cenozoic) Land Mammal Age, Argentina
- Author
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Garniss H. Curtis, Robert E. Drake, Larry G. Marshall, and Robert F. Butler
- Subjects
Paleontology ,Paleomagnetism ,Multidisciplinary ,Geography ,Early Pleistocene ,Range (biology) ,North American land mammal age ,Fauna ,parasitic diseases ,Geochronology ,Mammal ,Cenozoic - Abstract
Mammal faunas collected from the Uquía Formation at Chucalezna and Esquina Blanca in Jujuy Province, northwest Argentina, are calibrated by potassium-argon age determinations and paleomagnetic polarity data. The sediments range in age from 2.5 million years old to perhaps as young as 1.5 million years, from late Pliocene through early Pleistocene, and correspond in time to late Blancan and early Irvingtonian land mammal age faunas in North America.
- Published
- 1982
- Full Text
- View/download PDF
26. Notes on the Deciduous Dentition of the Borhyaenidae (Marsupialia: Borhyaenoidea)
- Author
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Larry G. Marshall
- Subjects
Orthodontics ,Ecology ,biology ,Genetics ,Borhyaenidae ,Animal Science and Zoology ,Deciduous dentition ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation - Published
- 1976
- Full Text
- View/download PDF
27. Evolution of metatherian and eutherian (mammalian) characters: a review based on cladistic methodology
- Author
-
Larry G. Marshall
- Subjects
Docodonta ,Prototheria ,Theria ,Monophyly ,Multituberculata ,biology ,Eutheria ,Zoology ,Animal Science and Zoology ,Metatheria ,Evolution of mammals ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics - Abstract
Cladistic methodology is used to test the hypothesis that three major monophyletic groups exist among living mammals–the oviparous monotremes (Prototheria), and the viviparous marsupials (Metatheria) and placentals (Eutheria). Evaluation is made of the polarity (i.e. the direction of change in a primitive-to-derived sequence) of numerous characters which distinguish some or all of these groups, and of the usefulness of these characters in phylogenetic inference. An attempt is made to establish the state of these characters in the common Late Jurassic-Early Cretaceous therian ancestor of marsupials and placentals. It is concluded that the most basic division of the Mammalia is the dichotomy into the subclasses Prototheria (including Monotremata, Multituberculata, Triconodonta, Docodonta) and Theria (including Metatheria, Eutheria, Pantotheria and Symmetrodonta). Two major groups exist among living viviparous mammals, the Metatheria and Eutheria; in a cladistic framework these are sister-groups. It is demonstrated that there is no special (sister-group) relationship between monotremes and marsupials, and there is no justification for placing them in a group Marsupionta.
- Published
- 1979
- Full Text
- View/download PDF
28. Vertebrate paleontology, geology, and geochronology of the Tapera de López and Scarritt Pocket, Chubut Province, Argentina
- Author
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Garniss H. Curtis, Robert E. Drake, Richard Cifelli, and Larry G. Marshall
- Subjects
Paleontology ,Archaeohyracidae ,biology ,Scarrittia ,Fauna ,Geochronology ,Interatheriidae ,Leontiniidae ,Vertebrate paleontology ,biology.organism_classification ,Geology ,Pyrotherium - Abstract
Fossil land mammals were collected by G. G. Simpson in 1933–1934 at and near the Tapera de López in central Chubut Province, Patagonia, southern Argentina, from rocks now mapped as the Sarmiento Formation. These fossils are assigned to land mammal faunas of Casamayoran (Early Eocene), Mustersan (Middle Eocene), and Deseadan (late Early Oligocene through Early Miocene) age.40K-40Ar age determinations of eight basalt and two tuff units associated with the Deseadan age local fauna at Scarritt Pocket establish a geochronologic framework that calibrates the biostratigraphic record at this locality. The radioisotope dates obtained at Scarritt Pocket range from 23.4 Ma to about 21.0 Ma, and equate with earliest Miocene time. The Scarritt Pocket local fauna is the youngest dated Deseadan age fauna yet known in South America.Seven other localities have, or were reputed to have, local faunas of Deseadan age associated with dated volcanic units. Six of these localities are in Argentina (Gran Barranca, Cerro Blanco, Valle Hermoso, Pico Truncado, Cañadón Hondo, Quebrada Fiera de Malargüe) and one in Bolivia (Estratos Salla in the Salla-Luribay Basin). The stratigraphic relationships of the volcanic units with these local faunas is discussed, and the taxonomic content of each is reassessed.The Deseadan Land Mammal Age is defined by the earliest record of the land mammal genus Pyrotherium, which is from below a basalt dated at 33.6 Ma at Pico Truncado. Other early records of Pyrotherium occur below basalts dated at about 29 Ma at the Gran Barranca and Valle Hermoso, and from a 28.5 Ma level of the Estratos Salla. Thus, the lower boundary for Deseadan time is about 34 Ma.The youngest record of Pyrotherium is in the upper levels of the Estratos Salla dated at about 24 Ma. However, the Scarritt Pocket local fauna, which lacks Pyrotherium, permits placement of the upper boundary for Deseadan time at about 21.0 Ma. Late Deseadan time is surely, and the end of Deseadan time is apparently, marked by the last record of such groups as Proborhyaeninae (Proborhyaena), Rhynchippinae (Rhynchippus), Archaeohyracidae (Archaeohyrax), and the genera Platypittamys (Octodontidae), Scarrittia (Leontiniidae), Propachyrucos and Prohegetotherium (Hegetotheriidae), and Argyrohyrax (Interatheriidae), as these taxa are recorded in the Scarritt Pocket local fauna. Thus, Deseadan time extends from about 34.0 Ma to about 21.0 Ma, making it the Land Mammal Age with the longest known duration in South America.
- Published
- 1986
- Full Text
- View/download PDF
29. Variability, evolutionary rates, and allometry in dwarfing lineages
- Author
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Larry G. Marshall and Robert S. Corruccini
- Subjects
0106 biological sciences ,0301 basic medicine ,Ecology ,biology ,Paleontology ,Interspecific competition ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Macropus titan ,Dwarfing ,03 medical and health sciences ,030104 developmental biology ,Evolutionary biology ,Megafauna ,Taxonomy (biology) ,Allometry ,Sarcophilus laniarius ,General Agricultural and Biological Sciences ,Ecology, Evolution, Behavior and Systematics ,Marsupial - Abstract
Evolutionary “dwarfism” or “nanism” is the phenomenon in which a significant decrease in mean body size of a lineage (an ancestral-descendant sequence of populations) occurs through time. A detailed analysis of several Late Quaternary dwarfed marsupial lineages from Australia is given. Based on linear tooth dimensions of the dwarfed lineages, four points are considered: 1) percent dwarfing; 2) evolutionary rates of change of tooth dimensions; 3) variation within lineages before and after dwarfing; and 4) several aspects of multivariate dental allometry. [The lineages includeMacropus titan(fossil)—M. giganteus(Recent) andOsphranter cooperi(fossil)—O. robustus(Recent) in the family Macropodidae (kangaroos), andSarcophilus laniarius(fossil)—S. harrisii(Recent) in the family Dasyuridae (Tasmaniandevil).]Dental measurements led to these conclusions: 1) Species with the largest body size show the greatest size reduction, and the species with the smallest body size change the least. 2) Evolutionary rates for this reduction in Australian lineages are similar to comparable Post-Pleistocene dwarfed lineages in Europe. 3) Tooth width, especially posterior width, changes more rapidly than length. The first molar changes relatively slowly, especially in length. 4) Variability is higher in the dwarfed forms than in the larger ancestors. 5) Multivariate allometric rates of dwarfing are consistent with results for rates of change calculated in darwins for the relation between change in length and maximum width (and less so for the relation between M1 and M4 reduction). This pattern of dwarfing allometry is broadly similar to within-species allometry, and is quite dissimilar to synchronous interspecific allometry.Brief consideration is also given to taxonomy of dwarfing lineages and to problems of concurrent megafaunal extinctions. It is concluded that dwarfism is an adaptive process which is probably the result of a density-dependent factor(s) (i.e. a resource limited system).
- Published
- 1978
- Full Text
- View/download PDF
30. Calibration of the Great American Interchange
- Author
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Robert E. Drake, Garniss H. Curtis, Richard H. Tedford, Robert F. Butler, and Larry G. Marshall
- Subjects
Paleontology ,Multidisciplinary ,Geography ,Montehermosan ,Land bridge ,Fauna ,Tribe ,Before Present ,North American origin ,Magnetostratigraphy ,South American origin - Abstract
From radioisotopic (potassium-argon) age determinations of tuffs and magnetostratigraphy of Late Tertiary mammal-bearing beds in Catamarca Province, northwest Argentina, refined estimates have been obtained for the durations and boundaries of beds of Chasicoan (Middle Miocene) through Chapadmalalan (Pliocene) age. An age of 9.0 million years is tentatively accepted for the Chasicoan-Huayquerian boundary, 5.0 million years for the Huayquerian-Montehermosan boundary, and 3.0 million years for the Montehermosan-Chapadmalalan boundary. Procyonids (raccoons and their allies), a group of North American origin, are first recorded in South America in a level immediately below a unit dated at 6.0 million years. Cricetine rodents of the tribe Sigmodontini are first recorded in South America in beds of Montehermosan age in Argentina. Ground sloths, a group of South American origin, first appear in North America in Early Hemphillian time in beds dated between 9.5 and 9.0 million years. The Panamanian land bridge was established by 3.0 million years ago, and an interchange of the terrestrial faunas was well under way by Late Blancan time (around 2.5 million years before present) in North America and by Chapadmalalan time in South America.
- Published
- 1979
- Full Text
- View/download PDF
31. Late Cretaceous vertebrates, including mammals,from Tiupampa, Southcentral Bolivia
- Author
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Christian de Muizon, Carlos Villaroel, Larry G. Marshall, Alain Lavenu, Mireille Gayet, and Bernard Sigé
- Subjects
Lungfish ,Taxon ,Phylogenetic tree ,biology ,Space and Planetary Science ,Ecology ,Fauna ,Paleontology ,biology.organism_classification ,Cretaceous ,Geology - Abstract
A taxonomically diverse fossil fauna with small and medium size vertebrates was recovered from the Late Cretaceous (Maestrichtian) age El Molino Formation at Tiupampa, southcentral Bolivia. Among the known taxa, many new to science, are selacians, actinopterygians, lungfish, amphibians, lizards, snakes, turtles, crocodiles, and several mammals. This finding provides a unique and previously unavailable opportunity to understand debated aspects of the phylogenetic and biogeographic histories of these groups.
- Published
- 1983
- Full Text
- View/download PDF
32. South American Geochronology: Radiometric Time Scale for Middle to Late Tertiary Mammal-Bearing Horizons in Patagonia
- Author
-
Rosendo Pascual, Robert E. Drake, Larry G. Marshall, and Garniss H. Curtis
- Subjects
Basalt ,Paleontology ,Multidisciplinary ,Geochronology ,engineering ,Plagioclase ,Mammal ,Radiometric dating ,engineering.material ,Hiatus ,Late Miocene ,Geology ,Biotite - Abstract
Radiometric (potassium-argon) age determinations for basalts and tuffs associated with middle to late Tertiary mammal-bearing horizons in Patagonia, southern Argentina, permit refinement of boundaries and hiatuses between beds of Deseadan (early Oligocene) through Friasian (middle to late Miocene) age. At two localities beds of Deseadan age are overlain by basalts, which gave dates of 33.6 and 35.4 million years ago; 34.0 million years ago is tentatively accepted as a terminal date for known Deseadan. At several localities beds of Colhuehuapian age are underlain by basalts, which gave dates ranging from 28.8 to 24.3 million years ago; 25.0 million years is tentatively taken as a basal age for known Colhuehuapian. The paleontological hiatus between known Deseadan and known Colhuehuapian is thus in the order of 9.0 million years. Two tuffs from the Santa Cruz Formation (Santacrucian) gave ages of 21.7 and 18.5 million years. Plagioclase and biotite concentrates of an ignimbrite from the Collón Curá Formation (Friasian) gave ages ranging from 15.4 to 14.0 million years.
- Published
- 1977
- Full Text
- View/download PDF
33. Calibration of the age of mammals in South America
- Author
-
Larry G. Marshall
- Subjects
biology ,European land mammal age ,North American land mammal age ,Paleontology ,biology.organism_classification ,Foraminifera ,Geologic time scale ,Space and Planetary Science ,Absolute dating ,Stage (stratigraphy) ,parasitic diseases ,Mammal ,Cenozoic ,Geology - Abstract
Fossil land mammals from scattered localities in South America are used by vertebrate paleontologists to subdivide Cenozoic time. This practice has resulted in recognition of Land Mammal Ages based on unique suites of mammal genera inferred to have existed during a restricted interval of geologic time. South American land mammal ages have been partially calibrated in terms of an absolute age time scale by radioisotopic (40K-40Ar) age determinations of volcanic rocks associated with mammal-bearing strata and by magneto-stratigraphic correlation of these strata with the magnetic polarity time scale. These geochronologic data are used to verify and refine the ages of these beds as inferred from the composition and stage of evolution of the mammal faunas contained in them. Detailed studies of marine faunas (especially foraminifera) from beds associated with continental mammal-bearing strata (i.e. marine-non marine tie-ins) permit further refinement of earlier chronologies and serve as a check on the geochronologic studies. Most geochronologic studies (reviewed here) have been made on the taxonomically rich Argentine mammal-bearing strata which represent the key to understanding mammalian evolution on the South American continent. In fact, all but one of the South American land mammal ages recognized in this study were defined on Argentine beds and faunas.
- Published
- 1982
- Full Text
- View/download PDF
34. Geochronology of Type Santacrucian (Middle Tertiary) Land Mammal Age, Patagonia, Argentina
- Author
-
Charles W. Naeser, Robert F. Butler, Robert E. Drake, Larry G. Marshall, Garniss H. Curtis, and Kathy M. Flanagan
- Subjects
Paleontology ,Geologic time scale ,Fauna ,Geochronology ,Geology ,Mammal ,Radiometric dating ,Tertiary ,Cenozoic ,Magnetostratigraphy - Abstract
Mammal-bearing lacustrine and tuffaceous sediments from three localities of the Santa Cruz Formation, type fauna of the Santacrucian Land Mammal Age, in Patagonia, southern Argentina, are calibrated by radioisotope dating with the aid of magnetostratigraphy. The strata range from about 17.6 Ma to perhaps 16.0 Ma, and are thus of late-early Miocene age. The Santacrucian Land Mammal Age ranges from about 18.0 Ma to about 15.0 Ma.
- Published
- 1986
- Full Text
- View/download PDF
35. Biosynthesis of phenazines
- Author
-
Ulrich. Hollstein and Larry G. Marshall
- Subjects
Carbon Isotopes ,chemistry.chemical_compound ,Biochemistry ,Biosynthesis ,Chemistry ,Pseudomonas ,Pseudomonas aeruginosa ,Organic Chemistry ,Phenazines ,Shikimic Acid ,Ketones - Published
- 1972
- Full Text
- View/download PDF
36. Acyonidae Ameghino, 1889 (Mammalia): Supplement To Proposal To Suppress This Name. Z.n.(S.) 2159
- Author
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William D. Turnbull, R J Hoffstetter, Bryan Patterson, Larry G. Marshall, R Pascual, Richard H. Tedford, and W A Clemens
- Published
- 1978
- Full Text
- View/download PDF
37. First Pliocene Record of the Water Opossum, Chironectes minimus (Didelphidae, Marsupialia)
- Author
-
Larry G. Marshall
- Subjects
Ecology ,biology ,Opossum ,Genetics ,Zoology ,Animal Science and Zoology ,Chironectes ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation - Published
- 1977
- Full Text
- View/download PDF
38. Why kangaroos hop
- Author
-
Larry G. Marshall
- Subjects
Family macropodidae ,Multidisciplinary ,Zoology ,Biology ,Cursorial - Abstract
KANGAROOS (family Macropodidae, order Marsupialia) are the only known group of large Australian herbivorous marsupials ever to have evolved major cursorial specialisations. During fast locomotion macropodids progress by a ricochet (bipedal saltation) involving a series of rebounds in which the two hind feet strike the ground at the same moment or practically synchronously and the forefeet not at all1. In macropodids the axis of the hind foot is through digit IV which is unique among large cursorial mammals; perissodactyls and most rodents have the axis through digit III, while in artiodactyls, carnivores and leporids it lies between digit III and IV2. These differences are the result of preadaptive complexes in the immediate ancestors of these groups.
- Published
- 1974
- Full Text
- View/download PDF
39. THE GREAT AMERICAN INTERCHANGE – AN INVASION INDUCED CRISIS FOR SOUTH AMERICAN MAMMALS
- Author
-
Larry G. Marshall
- Subjects
Taxon ,Geography ,Range (biology) ,Ecology ,Land bridge ,South american ,Fauna ,parasitic diseases ,Cenozoic - Abstract
During the Age of Mammals, South America was an isolated continent until the emergence of the Panamanian land bridge about 3.0 Ma; thereafter an intermingling of the long-separated North and South American faunas occurred. This, The Great American Interchange , is the most spectacular and best documented record of a reciprocal invasion of long separated continental faunas. In an attempt to understand short and long term consequences of faunal invasions of this magnitude taxonomic evolution (i.e. measurements of changes in number or frequency of different taxa) based on range distributions of families and genera of fossil mammals in South America is analyzed.
- Published
- 1981
- Full Text
- View/download PDF
40. Evolution of the Carnivorous Adaptive Zone in South America
- Author
-
Larry G. Marshall
- Subjects
Ecological niche ,Animal groups ,Geography ,Exploit ,biology ,Ecology ,biology.animal ,Adaptive radiation ,Fauna ,Partition (politics) ,Sparassodonta ,Vertebrate ,biology.organism_classification - Abstract
The role assumed by an animal group in a community is best understood when the structure of the community is viewed in historical perspective (MacArthur, 1972; Pianka, 1974). In many environments it is not physiological and behavioral limitations which guide a group’s evolutionary strategy, but the opportunity to exploit available adaptive zones, which because of the nature of the fauna, were vacated (Hecht, 1975:248). It is often assumed or implied that a particular systematic group can, in its adaptive radiation, fill all the available niches within a particular adaptive zone (Hecht, 1975:247). The type of analysis of a “taxocene” (Whittaker, 1972:218) which promotes these views has obvious shortcomings. It is now evident that mammals, for example, were unable to equally exploit and partition available adaptive zones on every continent. The failure of mammals to do this to a complete degree in Australia (see Hecht, 1975:247) and in South America (see below) has some historical basis in the development of the stratification of the vertebrate fauna.
- Published
- 1977
- Full Text
- View/download PDF
41. The Deseadan, early Oligocene, Marsupialia of South America / Bryan Patterson -- and Larry G. Marshall
- Author
-
Larry G. Marshall and Bryan Patterson
- Subjects
Paleontology ,Geography ,Archaeology - Published
- 1978
- Full Text
- View/download PDF
42. Calibration of the beginning of the age of mammals in patagonia
- Author
-
Garniss H. Curtis, Robert F. Butler, Robert E. Drake, and Larry G. Marshall
- Subjects
Paleontology ,Paleomagnetism ,Multidisciplinary ,Geography ,Calibration (statistics) ,Polarity (physics) ,Fauna ,North American land mammal age ,Mammal ,Cenozoic - Abstract
Beds of the Rio Chico Formation containing the earliest known land mammals in Patagonia, southern Argentina, were calibrated by potassium-argon age determinations and paleomagnetic polarity data. The Riochican land mammal age encompasses the middle and late Paleocene and corresponds in time with Torrejonian and Tiffanian land mammal faunas in North America.
- Published
- 1981
43. Systematics of the South American marsupial family Microbiotheriidae / Larry G. Marshall
- Author
-
Larry G. Marshall
- Subjects
Systematics ,Evolutionary biology ,South american ,Zoology ,Biology ,biology.organism_classification ,Marsupial - Published
- 1982
- Full Text
- View/download PDF
44. First radioisotope (potassium-argon) age of marine neogene rionegro beds in northeastern patagonia, Argentina
- Author
-
Garniss H. Curtis, William J. Zinsmeister, Larry G. Marshall, and Robert E. Drake
- Subjects
Paleontology ,Multidisciplinary ,Geologic time scale ,Stage (stratigraphy) ,Age estimation ,Isotopes of argon ,Radiometric dating ,Tertiary ,Neogene ,Archaeology ,Cenozoic ,Geology - Abstract
An average age of 9.41 million years was obtained from radioisotope (potassium-argon) age determinations of three glass concentrates of a tuff from the upper part of the marine Rionegrense at Punta Cracker in Golfo Nuevo, Argentina. This age correlates with the Tortonian marine stage of Europe and the Chasicoan Land Mammal Age of South America.
- Published
- 1981
45. Review of the Prothylacyninae, an extinct subfamily of South American 'dog-like' marsupials / Larry G. Marshall
- Author
-
Larry G. Marshall
- Subjects
Subfamily ,biology ,Anthropology ,South american ,Sparassodonta ,biology.organism_classification ,Genealogy - Published
- 1979
- Full Text
- View/download PDF
46. Systematics of the South American marsupial family Caenolestidae / Larry G. Marshall
- Author
-
Larry G. Marshall
- Subjects
Systematics ,biology ,Evolutionary biology ,South american ,Zoology ,biology.organism_classification ,Marsupial - Published
- 1980
- Full Text
- View/download PDF
47. The families and genera of Marsupialia / Larry G. Marshall
- Author
-
Larry G. Marshall
- Subjects
Geography ,Zoology - Published
- 1981
- Full Text
- View/download PDF
48. Systematics of the extinct South American marsupial family Polydolopidae / Larry G. Marshall
- Author
-
Larry G. Marshall
- Subjects
Systematics ,biology ,Evolutionary biology ,South american ,Zoology ,biology.organism_classification ,Marsupial - Published
- 1982
- Full Text
- View/download PDF
49. Mammalian evolution and the great american interchange
- Author
-
J. John Sepkoski, S. David Webb, David M. Raup, and Larry G. Marshall
- Subjects
Multidisciplinary ,Geography ,Ecology ,Land bridge ,media_common.quotation_subject ,Immigration ,Central American Seaway ,Evolution of mammals ,media_common - Abstract
A reciprocal and apparently symmetrical interchange of land mammals between North and South America began about 3 million years ago, after the appearance of the Panamanian land bridge. The number of families of land mammals in South America rose from 32 before the interchange to 39 after it began, and then back to 35 at present. An equivalent number of families experienced a comparable rise and decline in North America during the same interval. These changes in diversity are predicted by the MacArthur-Wilson species equilibrium theory. The greater number of North American genera (24) initially entering South America than the reverse (12) is predicted by the proportions of reservoir genera on the two continents. However, a later imbalance caused by secondary immigrants (those which evolved from initial immigrants) is not expected from equilibrium theory.
- Published
- 1982
50. Geology and geochronology of the mammal-bearing Tertiary of the Valle de Santa María and Río Corral Quemado, Catamarca Province, Argentina / Larry G. Marshall -- , Bryan Patterson
- Author
-
Bryan Patterson and Larry G. Marshall
- Subjects
Geochronology ,Mammal ,Physical geography ,Archaeology ,Geology - Published
- 1981
- Full Text
- View/download PDF
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