Systematics and palaeobiology of some Cambrian hyoliths from Guizhou, China, and Nevada, USA

Hyoliths constitute one of the most important groups of early biomineralized metazoans. Abundant hyolith specimens, comprising both hyolithides and orthothecides, from the Balang Formation (Cambrian Stage 4), Guizhou, China, and the Poleta Formation (Cambrian Stages 3-4), Pioche Formation (Stages 4-5) and Emigrant Formation (Stages 4-5) Nevada, USA, add to the early Palaeozoic record of hyoliths from South China and Laurentia, and provide new taxonomic, taphonomic and palaeoecologic information about this group. Hyoliths from the Balang Formation include the hyolithides Ambrolinevitus' maximus Jiang, 1982, Galicornus seeneus? Val'kov, 1975, Haplophrentis reesei Babcock & Robison, 1988, Linevitus' guizhouensis sp. nov., Meitanovitus guanyindongensis Qian, 1978, undetermined forms, and undetermined orthothecides. Hyoliths from Nevada include the hyolithides Haplophrentis carinatus (Matthew, 1899), Nevadotheca whitei (Resser, 1938), an undetermined form, and undetermined orthothecides. In the Balang Formation, eocrinoids have been found attached to hyolithide conchs, which supports the view that hyolithides were benthic animals.