ASSESSING OLD AND NEW DATA TO DIGITALLY RECONSTRUCT MORPHOLOGY

Traditionally, in order to assess the internal anatomy of Paleozoic invertebrates, acetate peels or serial sections were made of the specimen. The process of making acetate peels involves the cutting, polishing, etching, and chemical manipulation of the specimen, ultimately resulting in the destruction of the specimen. New imaging techniques, such as X-ray imaging via synchrotron or micro-CT, provide a nondestructive approach for assessment of internal morphology of ancient species. These techniques, however, cannot always differentiate the fine density variations between skeletal material and sediment infill that are present in many Paleozoic invertebrates. Herein we assess the differences between traditional and new imaging techniques by reconstructing the internal respiratory structures of extinct echinoderms via acetate peels and synchrotron imaging.

Acetate peels were created in the 1960s by A. Breimer and are reposited at the Naturalis Biodiversity Center in Leiden, Netherlands. Methodology to reconstruct the internal anatomy from scanned acetate peels was developed by collaborators at Appalachian State University and requires a program to render vectors into 3-D; in this study, we use Rhinoceros. For our synchrotron data, the internal anatomy was reconstructed using SPIERS. Here, the same species is reconstructed with each method to assess the major similarities and differences between the internal anatomical models. While both methods provided similar anatomical models, primary differences lie within the automatically generated external model with the synchrotron dataset. Additionally, both methods were time-consuming, however, reconstruction via SPIERS proved to be more time-efficient than the manual tracing and 3-D rendering in Rhinoceros.