title: Morphological stasis of protists in lower cretaceous amber.
abstract: 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 identified as members of the genus Chlamydomonas, and finally, in the taxon Ciliophora (Chromalveolata), 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.
authors.affiliation: Departamento de Microbiología-III, Universidad Complutense, 28040 Madrid, Spain. anamarti@bio.ucm.es
authors.forename: Ana
authors.initials: A
authors.lastname: Martín-González
authors.forename: Jacek
authors.initials: J
authors.lastname: Wierzchos
authors.forename: Juan C
authors.initials: JC
authors.lastname: Gutiérrez
authors.forename: Jesús
authors.initials: J
authors.lastname: Alonso
authors.forename: Carmen
authors.initials: C
authors.lastname: Ascaso
mesh_terms: D018647:Amber / Q000737:chemistry*; D000818:Animals; D005075:Biological Evolution; D002696:Chlamydomonas / Q000302:isolation & purification / Q000648:ultrastructure; D016798:Ciliophora / Q000302:isolation & purification / Q000648:ultrastructure; D005055:Euglena / Q000648:ultrastructure / Q000821:virology; D056890:Eukaryota / Q000145:classification / Q000302:isolation & purification* / Q000648:ultrastructure*; D005580:Fossils; D008855:Microscopy, Electron, Scanning; D013030:Spain
chemical_list: D018647:Amber