REEF-LECTING ON THE CAMBRIAN: TAXONOMIC REVISION AND LATERAL DISTRIBUTIONS OF SMALL SHELLY FAUNAS FROM REEF-ADJACENT FACIES OF THE UPPER HARKLESS FORMATION, NEVADA

Cambrian archaeocyathid reef systems represent the earliest metazoan-dominated topographically complex bioconstructions in the rock record and provide valuable insights into community composition with respect to the major framework builders and their small shelly fossil (SSF) inhabitants. This study focuses on lower Cambrian (Series 2, Stage 4) SSF assemblages from the Harkless Formation in southern Esmeralda County, Nevada, as a comprehensive systematic and quantitative analysis of these communities is currently lacking. This study investigates changes in SSF richness and diversity in relation to proximity to biohermal facies based on lithology and composition of SSF assemblages. Combining petrographic and quantitative analyses with a systematic review of the SSFs reveals a low diversity, but abundant assemblage. Trends in diversity and richness of species show no consistent patterns in distance from the reef across the measured 2 sections. However, lithology serves as a major control in determining SSF biofacies, with select fauna exhibiting evidence of additional taphonomic controls. More research is needed to understand spatial relationships and biodiversity across these ancient carbonate archaeocyathid reefs and platforms to determine key factors in maintaining biodiversity hotspots.