THREE DIMENSIONAL RECONSTRUCTION AND MORPHOLOGICAL ANALYSIS OF NAMAPOIKIA, A PUTATIVE EDIACARAN SPONGE FOSSIL, USING SERIAL GRINDING AND IMAGING

Among the first metazoans to biomineralize is Namapoikia, a putative sponge fossil that is found encrusting the sides of microbial mounds within the Ediacaran Driedoornvlakte reef complex, Namibia. Although not the earliest sponge in the fossil record, Namapoikia is unique because of its well preserved skeletal structure, which has been suggested to represent rapid and dynamic growth and a biological affinity to the coralline demosponge Vaceletia Sp. A morphological study of Namapoikia provides an opportunity to test existing theories about fluid flow and body plan development in sponge evolution.

We present the first-ever three dimensional reconstruction of Namapoikia, created using the Grinding, Imaging, and Reconstruction Instrument (GIRI) at Princeton University. We provide quantitative measurements of canal diameter and branching angles that reveal structural similarities between Namapoikia and modern calcareous sponges such as Sycon coactum. Using morphological data, we evaluate the potential for current induced flow through the sponge and, with this information, attempt to constrain paleoenvironmental conditions.