Disarticulated acanthodian and chondrichthyan remains from the upper Middle Devonian Aztec Siltstone, southern Victoria Land, Antarctica

Well-preserved vertebrate microremains are abundant in the residues from a calcareous grey siltstone in thekarawakabiozone (?late Givetian) of the Aztec Siltstone at Mount Crean, Lashly Mountains, Antarctica. Acanthodians are represented by scales of acritolepidPechoralepis juozasisp. nov., climatiidNostolepissp. cf.N. gaujensisValiukevičius, diplacanthidMilesacanthus antarcticaYoung & Burrow, and an undetermined acanthodiform. The acanthodian assemblage resembles those from early Frasnian carbonates of central Iran. Chondrichthyan elements in the fauna include rare teeth ofAztecodus harmsenaeLong & Young andAntarctilamna priscaYoung, ctenacanthoid-type scales and branchial denticles which are possibly fromAntarctilamna, and scales of an indeterminate chondrichthyan. An isolated set of acanthodid acanthodiform jaws from the uppermost ‘phyllolepid’ biozone of the Aztec Siltstone at Mount Ritchie, Warren Range, Antarctica is also described.