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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 6730

Ana Martin-Gonzalez, Jacek Wierzchos, Juan C. Gutierrez, Jesus Alonso, and Carmen Ascaso; Morphological Stasis of Protists in Lower Cretaceous Amber. Protist 159:251-257, 2008

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Paleomicrobiological studies of terrestrial and freshwater protists are extremely rare in comparison with studies of eukaryotic microfossils from marine ecosystems. Using optical and electron microscopy (SEM-BSE) for hard substrates, we have examined protists trapped in Lower Cretaceous amber from Penacerrada (Alava, Spain). We present the earliest reasonably confident microfossils of three taxa: Excavata (Euglenozoa), that are similar to the extant genera Euglena and Phacus; Chlorophyceae identified as members of the genus Chlamydomonas, and finally, in the taxon Ciliophora (Chromalvelolata), two ciliated protozoa identified as Colpoda (Class Colpodea) and Prorodon (Class Prostomatea). Morphological stasis is evident, and identification based on phenotypic traits indicates the existence of conservative phenotypes persisting over geological time scales.