A new chroococcacean alga from the proterozoic of queensland.

Nannofossils section sign here described are from the middle Proterozoic Paradise Creek Formation, along Paradise Creek in northwestern Queensland, Australia. These fossils, in chert blebs associated with branched stromatolites, comprise cubic colonies analogous to living Eucapsis, a member of the blue-green algal family Chroococcaceae. The age of the enclosing rocks, bracketed by the ages of older and younger granitic events, is about 1.6 x 10(9) years. We record, therefore, a new chronological and biological datum in the currently accumulating sequence of pre-Paleozoic microbiotas.