Events

Friday, November 3, 2017 - 11:30am
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Haller Hall (102), Geo Museum, 26 Oxford St., Cambridge

Paleobiology Seminar

"Spatial Analysis of Ediacaran Ecosystems: A New Approach to Illuminate the Origins of Complex Life" with Emily Mitchell, Henslow Research Fellow – Murray Edwards College, Department of Earth Sciences, University of Cambridge.

Abstract: Ediacaran macro-organisms occupy a crucial position in the history of life on Earth, marking the transition between the microbially dominated Proterozoic and the Cambrian explosion of modern animals.   The oldest Ediacaran macro-organisms exhibit unique morphologies, making it difficult to resolve their phylogenetic relationships or their basic ecology.  However, the sessile nature of these Ediacaran macro-organisms, coupled with their in-situ preservation, means that their spatial positions reflect the biological and ecological processes that they were subject to in-life.  As a result, detailed spatial analyses moves beyond descriptive statistics, enabling verifiable predictions to be made and ecological hypotheses to be tested.  
Using a high-resolution tripod-mounted Laser Line Probe, we have comprehensively mapped 18 of the most diverse and abundant Ediacaran communities across Newfoundland, Canada and Charnwood Forest, UK, to a resolution of ~40 µm.  By analysing the relationship of specimen height with spatial distributions, we found that competition for water-column resources did not structure these ecosystems, with the key advantage of large body-size limited to greater dispersal, contrary to previous suggestions. Furthermore, stemmed organisms do not exhibit any tiering, in contrast to non-stemmed organisms, illustrating that this morphological differentiation was also not driven by resource competition but by reproductive concerns.  The relatively low-levels of direct inter-specific competition, likely results in less pressure for niche creation, thus speciation, which suggests it is longer-term abiotic processes that underlie Ediacaran speciation. 
 

Contact Name: 

Milena Perez

Research Areas: 

Harvard University
Center for the Environment

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