214-4 New Ediacaran fossils of the White Sea assemblage from the Blueflower Formation, Mackenzie Mountains, Northwest Canada

Session: The Neoproterozoic Earth and Life Co-evolution, Part II

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The Neoproterozoic famously conatins the advent and diversification of complex macroscopic life, including the oldest fossil animals. The record of such life is perhaps best known from the Ediacara Biota, where over 100 species of predominately soft-bodied organisms document critical steps in metazoan evolution. Although once envisioned as a singular group of enigmatic taxa, three successive faunal assemblages – the oldest Avalon, middle White Sea, and youngest Nama – are recognized from the Ediacaran, presenting evidence for variable diversity, morphology and behavior through time. Current understanding of such dynamics between these assemblages suggests that they represent the oldest known radiation and extinction events in the history of animal life, with environmental variability and/or biotic interactions often implicated. Unfortunately, the overall rarity of localities yielding well-preserved and abundant examples of such fossils hampers our ability to correlate global events within a robust paleoenvironmental and chronostratigraphic framework. One of the most promising methods to resolve such uncertainties is to identify new fossil specimens and localities to test hypotheses regarding the pattern and drivers of change between Ediacaran assemblages. Here we report several new fossils from the Blueflower Formation near Sekwi Brook in the Mackenzie Mountains, Northwest Territories, Canada. These discoveries extend the paleogeographic range of several well-known Ediacaran forms and confirm correlation of this unit with the middle White Sea assemblage. Fossils further represent the oldest known examples of this assemblage in sedimentary facies characteristic of deep-water slope environments. This allows us to reconsider the pattern of change from the oldest Ediacaran fossils of the Avalon assemblage to the most diverse White Sea assemblage. Although more geochronology is needed, results are consistent with a potential offshore-onshore evolutionary trajectory for various members of the Ediacara Biota, which may have been a unique characteristic of early animal evolution.     

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

doi: 10.1130/abs/2025AM-6632

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