266 The Neoproterozoic Earth and Life Co-evolution (Posters)

This session aims to enhance discussions and foster interdisciplinary collaborations to advance understanding of the Neoproterozoic Earth and life co-evolution. Contributions from paleontologists, geochemists, sedimentologists, Earth system modelers, and related fields are highly encouraged.

Wednesday, 22 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Environmental and biological implications for the distribution of Parvancorina at Nilpena Ediacara National Park, South Australia

Paper number: 266-1
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

The Ediacara biota represents the earliest complex macroscopic animal communities in the fossil record, and have revealed insights into early metazoan evolution and ecology. Exceptional preservation at Nilpena Ediacara National Park (NENP) has enabled the excavation of over 40 fossiliferous bedding surfaces from the Ediacara Member of the Rawnsley Quartzite, revealing 10,000s of individual Ediacaran fossils. Parvancorina, an anchor-shaped soft-bodied organism associated with rheotaxes, is a common taxon at both NENP and the White Sea of Russia. Here we examine the spatial distributions of four Parvancorina populations (1T-A, 1T-FA, TC-MM3, and WS-PARV), on beds that vary in mat maturity, depositional environment, and preservational conditions. Results show that populations composed of smaller individuals were strongly aggregated (1T-A), while larger individuals displayed spatial randomness (1T-FA and TC-MM3). One population, located in a particularly high-energy environment (WS-PARV), exhibited a heterogeneous Poisson distribution, indicating that the population varied in density across the bed and implying an external effect on the population. Our data indicate that the spatial distribution of Parvancorina changes over their lifetime, with juveniles occurring within an aggregated spat while adults are found in random distributions. This further confirms that, at least within certain environments at NENP, there was limited competition and a relative abundance of resources for the adult Parvancorina. The variability in density of the Parvancorina population on WS-PARV suggests that their pattern was heavily influenced by biostratinomy, with strong currents likely removing large portions of the population. This current is indicated by the presence of toolmarks, otherwise highly uncommon on NENP beds, as well as stretched and twisted Dickinsonia, and pulled out fronds.

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

doi: 10.1130/abs/2025AM-412486

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