Calicioid lichens from European Tertiary amber.

Two species of calicioid lichens (Ascomycota) are reported from Baltic amber dating back 55-35 million years ago. The fossils are very similar to some modern Calicium and Chaenotheca species, but because ascus characteristics and photobiont identities cannot be determined they are not assigned to any extant species. Calicioid lichens seem to show a conservative maintenance of morphological adaptations to successful ecological niches, as do several other groups of ascomycetes. The fossils demonstrate that distinguishing features in the morphology of both genera have remained unchanged for at least tens of millions of years. The palaeohabitat of the fossil lichens, viz. that of conifer trunks in a humid, mixed forest, is consistent with the habitat preferences of many modern Calicium and Chaenotheca species.