October 9, 2013

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Aaron Sappenfield Co-Authors Article on Discovery of Earth's Oldest Zoophycos Organisms

Aaron Sappenfield, a geologist in Geosyntec's Huntington Beach office, is the co-author of a new paper, "The Oldest Zoophycos and Implicationsfor Early Cambrian Deposit Feeding," published in the June 12 issue of Geological Magazine.

In their paper (available online), Aaron and his co-authors describe their discovery of evidence that soil-mixing organisms date back to about 540 million years ago. The paper documents the oldest known specimens of the enigmatic ichnofossil, Zoophycos. Aaron wrote the paper with Mary Droser and Ryan McKenzie of the University of California, Riverside (UCR), along with Martin Kennedy of the University of Adelaide in Australia.

The authors' discovery of the ancient specimens in southeastern California provide robust evidence of deposit feeding in close proximity to the Precambrian-Cambrian boundary. The fossils reveal the presence of deposit feeding considerably earlier than has been suggested for the advent of this feeding style. Deposit feeding and the potential to effectively mix sediment by mining large volumes of sediment were key steps in the evolution of animals that fundamentally changed the nature of our ecosystems and altered the physical and chemical characteristics of sediment.

Aaron joined Geosyntec in 2011 and has directed projects involving surface and subsurface investigations, geological mapping and drilling, geophysical and downhole logging, sampling of soils for laboratory testing, and similar geochemical/geotechnical assessments. He earned his M.S. in geological sciences in 2009 and his B.S. in business administration in 2003, both from UCR.