EAPSI: Determining the Biology and Ecology of One of Earth's Earliest animals: Dickinsonia

Evans Scott, Riverside CA

Investigators

Abstract

Fossils of the Ediacara biota, represent the earliest evidence of macroscopic, multicellular organisms on Earth. This diverse fauna of soft-bodied organisms helps to bridge the evolutionary gap between microscopic, unicellular life forms known to exist through most of Earth's early history and the complex, familiar forms that exists today. Dickinsonia is a common and diverse member of this biota, however it remains poorly understood. Determining the ecology and biology of this early organism will provide critical insight to our understanding of the evolution of early life. Abundant fossils, including hundreds of Dickinsonia have been identified in the Flinders Ranges area of South Australia and many are housed in the South Australia Museum (SAM). Travel to South Australia will allow access to this unparalleled data set and permit collaboration with Dr. Jim Gehling (at the SAM), the premier expert on specimens from this region. Study of Dickinsonia from the Ediacaran deposits of South Australia will be conducted in order to test two hypotheses: 1) previously determined species distinctions can be identified using morphologic differences and are not an artifact of varying preservational modes; and 2) Dickinsonia had preferred environmental habitats and was one of the most abundant organism of the Ediacara biota. Data will also be used to address the extent to which size frequency and spatial patterns can inform us about the autecology and synecology of this unique organism. These hypotheses will be tested through four objectives: 1) identify morphological variability in order to investigate speciation; 2) to determine dominance and environmental preference using photographs of entire bed surfaces along with detailed reports of presence, absence, and abundance of Dickinsonia; 3) bed scale observations of size and abundance data will also be documented as well as spatial relations between Dickinsonia and other taxonomic groups to examine the ecologic importance of this ancient organism; and 4) evaluate potential preservation biases in this fossil record. This NSF EAPSI award is funded in collaboration with the Australian Academy of Science.