Reprint of ‘Eighty years of chitinozoan research: From Alfred Eisenack to Florentin Paris’

• We review the research on Chitinozoa since their first description in the 1930s.
• Chitinozoa (or “chitinozoans”) became a major microfossil group in the Palaeozoic.
• Original studies, including the creation of the name, date back to Alfred Eisenack.
• Most modern studies, since the 1970s, have been coordinated by Florentin Paris.

In the early 1930s Alfred Eisenack first reported unknown, bottle-shaped, organic-walled microfossils that he had discovered in erratic boulders from the south-eastern shores of the Baltic Sea. Eisenack erected the new group Chitinozoa to classify these strange microfossils of unknown biological affinity. From the 1930s to the 1950s, a few publications appeared reporting new findings and providing descriptions of these fossil organisms. It was only since the 1960s, with the development of the oil industry and the intensive biostratigraphical use of organic-walled microfossils, that publications dealing with chitinozoans became more numerous and that the description of new genera and species rapidly increased. The peak of description of new species was reached in the 1960s, but the number of publications remained high into the late 1990s. Since the 1990s the research activities on chitinozoans are conducted by a much smaller number of scientists. One of the major driving forces of chitinozoan research in the last forty years was Florentin Paris at the University of Rennes (Brittany, France). He first established a high-resolution chitinozoan biostratigraphy of the Ordovician of southern Europe and played an active role in bringing all scientists together for the development of global biostratigraphical schemes and palaeobiogeographical scenarios of the Ordovician, Silurian and Devonian. It was also Florentin Paris, together with his Estonian colleague Jaak Nõlvak, who suggested the now widely accepted biological interpretation that Chitinozoa are most probably egg cases of a planktonic organism unknown from the fossil record. F. Paris was also the first to collaborate w ith experts to use biogeochemical analyses and the C isotope signal of the chitinozoans to better understand their biological affinity and detect biogeochemical changes in Palaeozoic oceans.