Résumé
Do terrestrial micro-organisms evolve morphologically? A recent concept suggests that morphological stasis over dozens of millions of years has persisted in microbial lineages. However, it is based on a weak fossil record. Indeed, it is already difficult to define a species with extant microbes, and this task is even harder when dealing; with fossil microorganisms. Based on research on fossils in amber, we highlighted the different problems that are raised when describing a new fossil species of micro-organisms and we discuss the concept of morphological stasis. (C) 2010 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.