Akshay Mehra – Princeton University

Statement of Purpose:

Recent studies have suggested that Cloudina, one of the oldest known, putatively biomineralizing metazoans (i.e., animals that create hard skeletal parts), played a dominant role in reef construction as early as the late Ediacaran (~547 Ma). If true, this assertion would imply that metazoans were able to respond to and shape their environments well before the Cambrian radiation. This, in turn, would have broad implications for the development and evolution of biomineralization, the introduction of permanent, aggregated growth as an ecological strategy, and the diversity, architecture and morphology of Ediacaran reef systems and associated carbonate platforms. In order to test whether Cloudina actively built frameworks at the eve of the Cambrian radiation, it is important to quantitatively understand both the morphology of individual and aggregate Cloudina specimens, as well as the size, shape, and distribution of the structures that the organisms produced and/or lived amongst. In this study, the paleoenvironment of Cloudina reefs are contextualized using high resolution drone-derived aerial imagery, differential GPS survey data, field observations, and isotope geochemistry. Since a lack of density contrast prevents any sort of X-ray tomography, aggregations of Cloudina are reconstructed in three dimensions with the use of serial sectioning, digital imaging, and supervised classification. The reconstructed data sets (the first of their kind) are used to produce spatial statistics (e.g., length, diameter, connectivity, orientation, and curvature) that can describe the growth habit and life-cycles of Cloudina.


Description of Data Sets:

The data sets used in the proposed presentation are:
1) high resolution (i.e., greater than 10 centimeters/pixel) aerial orthoimagery and digital elevational models produced over the course of two field seasons using drones equipped with both RGB and NIR cameras;
2) digital three-dimensional volumes composed of 800 to 1000 images (each with a resolution of 5.6 microns/pixel) arranged in a vertical stack; all images are captured by GIRI (Grinding, Imaging, and Reconstruction Instrument) at Princeton University;
3) digital three-dimensional models of Cloudina, the first biomineralizing metazoan, developed by an image classification and segmentation pipeline that was designed to handle the large datasets created by GIRI.
All data sets are the result of work done as a graduate student in the Maloof Lab at Princeton University. More information on GIRI can be found at: http://giri.princeton.edu/#giri