47
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Late Cretaceous Aquatic Plant World in Patagonia, Argentina

      research-article

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          In this contribution, we describe latest Cretaceous aquatic plant communities from the La Colonia Formation, Patagonia, Argentina, based on their taxonomic components and paleoecological attributes. The La Colonia Formation is a geological unit deposited during a Maastrichtian-Danian transgressive episode of the South Atlantic Ocean. This event resulted in the deposition of a series of fine-grained sediments associated with lagoon systems occurring along irregular coastal plains in northern Patagonia. These deposits preserved a diverse biota, including aquatic and terrestrial plants and animals. The aquatic macrophytes can be broadly divided into two groups: free-floating and rooted, the latter with emergent or floating leaves. Free-floating macrophytes include ferns in Salviniaceae ( Azolla and Paleoazolla) and a monocot (Araceae). Floating microphytes include green algae ( Botryoccocus, Pediastrum and Zygnemataceae). Among the rooted components, marsileaceous water ferns (including Regnellidium and an extinct form) and the eudicot angiosperm Nelumbo (Nelumbonaceae) are the dominant groups. Terrestrial plants occurring in the vegetation surrounding the lagoons include monocots (palms and Typhaceae), ferns with affinities to Dicksoniaceae, conifers, and dicots. A reconstruction of the aquatic plant paleocommuniy is provided based on the distribution of the fossils along a freshwater horizon within the La Colonia Formation. This contribution constitutes the first reconstruction of a Cretaceous aquatic habitat for southern South America.

          Related collections

          Most cited references4

          • Record: found
          • Abstract: found
          • Article: found
          Is Open Access

          High Diversity, Low Disparity and Small Body Size in Plesiosaurs (Reptilia, Sauropterygia) from the Triassic–Jurassic Boundary

          Invasion of the open ocean by tetrapods represents a major evolutionary transition that occurred independently in cetaceans, mosasauroids, chelonioids (sea turtles), ichthyosaurs and plesiosaurs. Plesiosaurian reptiles invaded pelagic ocean environments immediately following the Late Triassic extinctions. This diversification is recorded by three intensively-sampled European fossil faunas, spanning 20 million years (Ma). These provide an unparalleled opportunity to document changes in key macroevolutionary parameters associated with secondary adaptation to pelagic life in tetrapods. A comprehensive assessment focuses on the oldest fauna, from the Blue Lias Formation of Street, and nearby localities, in Somerset, UK (Earliest Jurassic: 200 Ma), identifying three new species representing two small-bodied rhomaleosaurids (Stratesaurus taylori gen et sp. nov.; Avalonnectes arturi gen. et sp. nov) and the most basal plesiosauroid, Eoplesiosaurus antiquior gen. et sp. nov. The initial radiation of plesiosaurs was characterised by high, but short-lived, diversity of an archaic clade, Rhomaleosauridae. Representatives of this initial radiation were replaced by derived, neoplesiosaurian plesiosaurs at small-medium body sizes during a more gradual accumulation of morphological disparity. This gradualistic modality suggests that adaptive radiations within tetrapod subclades are not always characterised by the initially high levels of disparity observed in the Paleozoic origins of major metazoan body plans, or in the origin of tetrapods. High rhomaleosaurid diversity immediately following the Triassic-Jurassic boundary supports the gradual model of Late Triassic extinctions, mostly predating the boundary itself. Increase in both maximum and minimum body length early in plesiosaurian history suggests a driven evolutionary trend. However, Maximum-likelihood models suggest only passive expansion into higher body size categories.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: found
            Is Open Access

            Cretaceous/Paleogene Floral Turnover in Patagonia: Drop in Diversity, Low Extinction, and a Classopollis Spike

            Nearly all data regarding land-plant turnover across the Cretaceous/Paleogene boundary come from western North America, relatively close to the Chicxulub, Mexico impact site. Here, we present a palynological analysis of a section in Patagonia that shows a marked fall in diversity and abundance of nearly all plant groups across the K/Pg interval. Minimum diversity occurs during the earliest Danian, but only a few palynomorphs show true extinctions. The low extinction rate is similar to previous observations from New Zealand. The differing responses between the Southern and Northern hemispheres could be related to the attenuation of damage with increased distance from the impact site, to hemispheric differences in extinction severity, or to both effects. Legacy effects of the terminal Cretaceous event also provide a plausible, partial explanation for the fact that Paleocene and Eocene macrofloras from Patagonia are among the most diverse known globally. Also of great interest, earliest Danian assemblages are dominated by the gymnosperm palynomorphs Classopollis of the extinct Mesozoic conifer family Cheirolepidiaceae. The expansion of Classopollis after the boundary in Patagonia is another example of typically Mesozoic plant lineages surviving into the Cenozoic in southern Gondwanan areas, and this greatly supports previous hypotheses of high latitude southern regions as biodiversity refugia during the end-Cretaceous global crisis.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Cobbania corrugata gen. et comb. nov. (Araceae): a floating aquatic monocot from the Upper Cretaceous of western North America.

              The fossil record of aquatic flowering plants broadens our understanding of their former diversity and origins from terrestrial ancestors. This paper describes a floating aquatic monocot from 71 whole plants and several isolated leaf fragments from Upper Cretaceous oxbow lake sediments in the Dinosaur Park Formation, Alberta, Canada. The new material is represented by rosettes of leaves and roots attached to short stems that are interconnected by stolons and corresponds to the fossil aroid originally described as Pistia corrugata Lesquereux. Up to six plants have been found interconnected on a single slab suggesting that these plants grew in extensive floating mats covering lakes and calm stretches of rivers. Stems have up to six leaves and large numbers of branched aquatic roots. The leaf is trumpet-shaped with an elongate clasping petiole, large aerenchymatous base, and a nearly circular blade rim. Leaf bases are often filled with sediment giving the leaf the appearance of having a basal pouch. Petioles have 6-9 veins that divide into an upper and lower set, and veins converge at an apical notch. A submarginal collective vein and at least two marginal veins with branching veins form the leaf rim. A series of dichotomizing and anastomosing veins characterize the adaxial leaf surface. Tertiary and quaternary veins form polygonal areolae. Leaf surfaces are covered in trichomes that, like those in Pistia stratiotes, probably aided in buoyancy. A reconstruction of the plant is presented. Based on unique leaf morphology, these fossil plants are clearly not assignable to the genus Pistia and are described as Cobbania corrugata (Lesquereux) Stockey, Rothwell et Johnson gen. et comb. nov. Recent systematic analyses using molecular characters resolve two separate origins of floating aquatic aroids included in the duckweeds and the genus Pistia. This new fossil genus increases our understanding of colonization of aquatic habitats by revealing a third possible origin of the floating aquatic habit within Araceae.
                Bookmark

                Author and article information

                Contributors
                Role: Editor
                Journal
                PLoS One
                PLoS ONE
                plos
                plosone
                PLoS ONE
                Public Library of Science (San Francisco, USA )
                1932-6203
                2014
                22 August 2014
                : 9
                : 8
                : e104749
                Affiliations
                [1 ]Museo Paleontológico Egidio Feruglio - CONICET. Trelew, Chubut, Argentina
                [2 ]L. H. Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, New York, United States of America
                [3 ]Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
                [4 ]Department of Environmental and Plant Biology, Ohio University, Athens, Ohio, United States of America
                Wesleyan University, United States of America
                Author notes

                Competing Interests: The authors have declared that no competing interests exist.

                Conceived and designed the experiments: NRC MAG MCZ EJH. Performed the experiments: NRC MAG MCZ EJH. Analyzed the data: NRC MAG MCZ EJH. Contributed reagents/materials/analysis tools: NRC MAG MCZ EJH. Contributed to the writing of the manuscript: NRC MAG MCZ EJH.

                Article
                PONE-D-14-14317
                10.1371/journal.pone.0104749
                4141708
                25148081
                f73a58d5-f468-44f5-a8e8-098dcd9c6336
                Copyright @ 2014

                This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

                History
                : 2 April 2014
                : 15 July 2014
                Page count
                Pages: 1
                Funding
                Funding provided by Philosophical Society Franklin Award and United States National Science Foundation DEB-0918932 to MAG; National Science Foundation DEB-0919071 and CONICET 12410 to NRC; Agencia Nacional Promición Ciencia y Tecnología PICT 1696 to MCZ. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
                Categories
                Research Article
                Biology and Life Sciences
                Ecology
                Paleoecology
                Paleontology
                Paleobiology
                Paleobotany
                Earth Sciences
                Custom metadata
                The authors confirm that all data underlying the findings are fully available without restriction. All relevant data are within the paper and its Supporting Information files.

                Uncategorized
                Uncategorized

                Comments

                Comment on this article