| morphological stasis of protists in lower cretaceous amber. | 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 peñacerrada (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 ident ... | 2008 | 18032106 |