Thalloid organisms and the fossil record: New perspectives from the Transantarctic Mountains.

Thalloid body plans occur in several groups of organisms, including bryophytes, lichens and algae. While many aspects of the biology and ecology of extant thalloid organisms are well understood today, knowledge about the evolutionary history, palaeobiology and palaeoecology of these life forms remains limited. The recently discovered thalloid fossil Litothallus ganovex from the Triassic of Antarctica consists of fused vertical cell filaments forming a pseudoparenchymatous crust-like body, and most likely represents a freshwater macroalga. Other cuticle fragments from Antarctica are tentatively interpreted as remains of thallose liverworts. These unexpected new finds indicate that thalloid organisms are more frequent in the fossil record than previously assumed, and contribute to a better understanding of the palaeobiodiversity of ancient non-marine ecosystems.