Clitellate annelids have a meagre body fossil record but they secrete proteinaceous

cocoons for the protection of eggs that, after hardening, are readily fossilized

and offer a largely untapped resource for assessing the evolutionary history of this

group. We describe three species of clitellate cocoons (viz., Burejospermum seymourense

sp. nov., B. punctatum sp. nov. and Pegmatothylakos manumii gen. et sp. nov.)

from the lower Eocene La Meseta Formation, Seymour Island, Antarctica. The

cocoons probably derive from continental settings and were transported to, and preserved

within, nearshore marine to estuarine environments. The cocoons provide the

first evidence of commensal or parasitic relationships in the Eocene continental ecosystems

of Antarctica. Moreover, numerous micro-organisms and the oldest fossilized

examples of animal spermatozoa are preserved as moulds within the consolidated

walls of the cocoons. Fossil annelid cocoons offer potential for enhanced palaeoenvironmental

interpretation of sediments, correlation between continental and shallowmarine

strata, and improved understanding of the development of clitellate annelid

reproductive traits and the evolutionary history of soft-bodied micro-organisms in general.