CT RECONSTRUCTION OF EDIACARAN TRACE FOSSILS

The transition between the Ediacaran and Cambrian geological periods coincided with a dramatic increase in the diversity and complexity of bioturbation commonly known as the ‘Agronomic Revolution’. Most trace fossils from the Ediacaran period representing burrows are relatively simple, whereas after the Agronomic Revolution the trace fossils of the Cambrian period yield traces representative of more complex behaviors. Lamonte trevallis is an ichnospecies found in the Shibantan Member of the upper Ediacaran Dengying Formation, in the Yangtze Gorges region of South China. Most other trace fossils from the Shibantan Member are relatively simple in comparison to L. trevallis, which makes it a subject of interest when studying the changes in the trace fossil record that occurred as the Ediacaran period came to a close. Through the use of X-ray CT (computed tomography) technology, a hand sample containing a specimen of L. trevallis was scanned in order to observe the internal morphology of the fossil in situ. The data gathered from the scan was used to generate a stack of digital images, which clearly depict the internal features of the L. trevallis specimen. From these images, a three-dimensional model can be constructed by segmenting regions of interest in order to obtain information about the trace maker that was unavailable from external observations. These new three-dimensional images provide us with a greater understanding of L. trevallis’ relationship with sediment during this critical time in Earth history.