New insights into the earlier evolutionary history of epiphytic macrolichens

Abstract

Lichens are well known as pioneer organisms colonizing bare surfaces such as rocks and therefore have been hypothesized to play a role in the early formation of terrestrial ecosystems. Given the rarity of fossil evidence, our understanding of the evolutionary history of lichen-forming fungi is primarily based on molecular dating approaches. These studies suggest extant clades of macrolichens diversified after the K-Pg boundary. Here we corroborate the mid-Mesozoic fossil Daohugouthallus ciliiferus as an epiphytic macrolichen that predates the K-Pg boundary by 100 Mys. Based on new material and geometric morphometric analysis, we demonstrate that the Jurassic fossil is morphologically most similar to Parmeliaceae, but cannot be placed in Parmeliaceae or other similar family-level clades forming macrolichens as these evolved much later. Consequently, a new family, Daohugouthallaceae, is proposed here to accommodate this fossil, which reveals macrolichens may have been diverse long before the Cenozoic diversification of extant lineages.