219-3 Fossil Diversity and Abundance Across the Great Ordovician Biodiversification Event, Pogonip Group, Arrow Canyon Range, Nevada

Session: Paleontology, Diversity, Extinction, Origination (Posters)

Presenting Author:

Authors:

Abstract:

The Great Ordovician Biodiversification Event (GOBE) is understood to be the longest prolonged increase in biodiversity in the Earth’s history. Globally, marine biodiversity more than tripled over a thirty million year interval beginning in the Middle Ordovician, though the timing and magnitude of this event vary locally. The long-term impacts of the GOBE on the carbonate cycle and carbonate factories remain uncertain, particularly how skeletal biomass changed across this interval of mass diversification. Here, we report skeletal fossil abundance data from the Lower and Middle Ordovician Pogonip Group in the Arrow Canyon Range in southeastern Nevada. Ninety-five samples were point-counted to assess skeletal abundance and diversity from Pogonip Group units Opb, Opc, Opd, Ope, and Opf. Echinoderms, trilobites, and the calcareous algae Nuia are present in all units. The mean skeletal fossil abundance of each unit, as determined from our point-count data, ranges from 8 to 14% and does not increase across the Pogonip Group. We observe notable increases in diversity that initiate in the Dapingian Ope unit, but increases in abundance, at this locality, appear to deviate from diversification trends. Skeletal fossil abundance does not monotonically increase across the GOBE and appears to vary across environments. When we compare mean skeletal fossil abundance before, during, and after the GOBE, we identify a broadly increasing trend. However, across the GOBE itself, the variability in skeletal abundance likely reflects the influence of local environmental controls.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8722

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