Devonian vertebrate microremains from southeastern Australia: correlation with conodonts and inferred palaeoecology

Conodont studies in Victoria of the Buchan Group at Buchan and the Coopers Creek limestone at Tyers-Boola indicate conodont zonation of dehiscens-serotinus zones and sulcatusdehiscens zones respectively, allowing precise dating of the accompanying microvertebrates. The lowermost and uppermost units of the coeval Murrumbidgee Group at Burrinjuck, New South Wales, have been directly dated by conodonts, as ranging from pireneae to serotinus zones. Other studies of corals and brachiopods infer approximate conodont ages for these intermediate horizons. Accompanying vertebrate microremains from the limestones at Burrinjuck, Buchan and the Tyers-Boola area have extended the stratigraphic range of placoderms Brindabellaspis sp., Weejasperaspis sp., Buchanosteus sp., and Goodradigbeeon australianum, and acanthodians Nostolepoides platymarginata, Trundlelepis cervicostulata, and Gomphonchus? bogongensis. Known geographic ranges have been increased for placoderms Brindabellaspis sp., Weejasperaspis sp., Buchanosteus sp., and Wijdeaspis sp., acanthodians Nostolepoides platymarginata, Trundlelepis cervicostulata, Gomphonchus? bogongensis, “Nostolepis” guangxiensis, Cheiracanthoides sp cf C. wangi and Rhadinacanthus sp, chondrichthyan Ohiolepis sp and osteichthyans Ligulalepis sp and Onychodus sp. All three study areas were shallow marine in the early Devonian Microremains of chondrichthyan Ohiolepis sp. and osteichthyan Ligulalepis sp were more common in shallow water sediments, while more fossiliferous horizons tended to show some indication of a muddy substrate.