Acanthodian fauna from the Early Devonian (Emsian) of Death Valley, California
Abstract
A limited assemblage of disarticulated remains from stem chondrichthyan (acanthodian) gnathostomes was found associated with more abundant pteraspidiform and cyathaspidiform (agnathan) plates and plate fragments as well as actinolepid placoderm remains in the Lippincott Member of the Lost Burro Formation, southeastern California. The acanthodian material comprises ischnacanthiform, Bryantonchus, and Machaeracanthus fin spines, ischnacanthiform dentigerous jaw bones, and an endoskeletal scapulocoracoid. The assemblage mostly matches that from the Emsian Sevy Dolomite and the lower Grassy Flat Member of the Water Canyon Formation of Utah and Nevada. Machaeracanthus has not been recorded from the latter strata, but has been described from the Coils Creek Member (?Emsian), McColley Canyon Formation, Nevada.