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The morphological adaptation of Lithocodium aggregatum Elliott (calcareous green alga) to cryptic microhabitats (Lower Aptian, Spain): an example of phenotypic plasticity

    05.05.2011
Published in:
  • Facies : International Journal of Paleontology, Sedimentology and Geology. - 2012, vol. 58, no. 1, p. 37-55
Lithocodium aggregatum
Cryptic microhabitats
Phenotypic plasticity
Morphological adaptation
Lower Aptian
Spain
English Lithocodium aggregatum Elliott is interpreted as a heterotrichale chlorophycean alga with a prostrate and erect system within a well-calcified tissue. Within Lower Aptian coral rubble of the western Maestrat Basin, Spain, it forms thick masses of juxtaposed crusts around the bioclasts. In achieving a rapid and complete encrustation of the available bioclasts, Lithocodium applied several strategies, e.g., filling voids of structured surfaces with a special fabric or forming erect extensions to bridge adjacent substrates. In these deposits, different types of poorly if ever illuminated cryptic microhabitats can be distinguished: (1) existing crypts such as empty shells or structural voids within bioclasts (2) crypts resulting from the complete encrustation of adjacent bioclasts by Lithocodium itself and (3) syndepositionally created crypts, e.g., boreholes produced by lithophagid bivalves. In these cases, Lithocodium developed a poorly calcified structure of large cells with thin microcrystalline walls indicating a high degree of variability (phenotypic plasticity). This cryptic growth stage is interpreted as an adaption to the poorly illuminated crypts (photoadaption) in order to maximize light capture for photosynthesis. The Lower Cretaceous Lithocodium is therefore not per se a cryptoendolithic microorganism, but may show adaptation to develop and survive also in these already existing or newly created niches.
Faculty
Faculté des sciences et de médecine
Department
Département de Géosciences
Language
  • English
Classification
Palaeontology
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/302069
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