T103 Dynamic Environments Across the Ediacaran-Cambrian Boundary and the Rise of Early Animals (Posters)

Monday, 23 September 2024
8:00 AM - 5:30 PM
Hall D

THE EDIACARAN AQUARIUM: INSIGHTS FROM THE NILPENA EDIACARA NATIONAL PARK 1T-F MARINE ECOSYSTEM (EDIACARA MEMBER, RAWNSLEY QUARTZITE)

Paper number: T103-1
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

The Ediacaran Period, spanning 635 to 538 million years ago, marks a pivotal phase in life’s evolutionary history, showcasing early multicellular animal life. The remarkable fossil bed, 1T-F, from the Ediacara Member of the Rawnsley Quartzite at Nilpena Ediacara National Park, South Australia, offers insights into a shallow marine ecosystem during the Ediacaran period. 1T-F, preserving over 400 fossils across 16 metazoan-grade genera and numerous multicellular algae, exhibits remarkable ecological complexity and diversity. A detailed examination reveals a stable, low-energy environment that fostered diverse life forms. Taxa include Dickinsonia, Spriggina, Aulozoon, Parvancorina, Tribrachidium, Rugoconites, and many more with a Shannon Diversity index of 2.09.

Comparative studies with other fossil beds emphasize ecological dynamics only discernible with the incredible preservation provided by 1T-F. Spatial Point Pattern Analysis reveals that the population of 35 Sprigginamophs, a mm-scale taxon within the larger Spriggrinamorphotype, were found to be spatially attracted to the 32 Dickinsonia on 1T-F. Analysis of Spriggnamorph orientation indicates that they are oriented parallel to each other and to nearby Dickinsonia, which is significant as 1T-F does not show significant current influence. Dickinsonia and Sprigginamorph do co-occur on other bedding surfaces at Nilpena Ediacara National Park that do not show this spatial relationship indicating this relationship is not obligatory. Here we propose this to be the earliest known record of a nuclear-follower foraging association where Dickinsonia are the nuclear taxa and the Sprigginamorphs are the followers. This provides valuable insights into the evolutionary transitions preceding the Cambrian Explosion and enhances our understanding of early multicellular ecosystems.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-404144

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