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Pteridinium continues to be one of the most confounding of the Ediacaran fossils despite almost a century of investigation. It remains steadfastly in the Vendobionta, with its biological affinities remaining enigmatic, whereas other Ediacarans, such as Dickinsonia and Kimberella, have been placed into "modern" taxonomic groups. In the past few decades, discoveries of new quilted, triple-bladed organisms have initiated a debate as to the genera-level attributes of the group. The primary differences in these specimens are reflected in blade size (but not individual quilt size) as well as how the blades attach to one another. Some authors speculate that Pteridinium, as classically defined, only exists in Namibia, whereas others contend that all of these forms, regardless of location, are morphologically identical and simply deformed during preservation.
To date analyses of Pteridinium's morphology have been largely based on length, width, quilt size, and the number of quilts. While these are quantitative measurements, they may not effectively represent the true nature of the complex system that is an organism's morphology. This study uses geometric morphometrics - a technique that more efficiently analyzes spatial relationships of morphometric data - to compare the morphologies of Pteridinium specimens from three different sites: Namibia, the White Sea region, and North Carolina. By using standardized landmarks defined for Pteridinium this method removes confounding variables such as location, scale, and rotational effects, retaining data on the organism's shape.
With a landmark system, deformation caused by lithification or metamorphic alteration can be corrected for. Preliminary data from Namibian Pteridinium suggests that its morphology is more complex than originally believed. Whereas this study found correlating evidence for the previously established growth patterns in Pteridinium, it also suggests a modification in its reconstructed life position. There appears to be a more "robust" blade preserved on each specimen. The base of this blade, which runs along the long axis of the organism, is oriented into the substrate at a higher angle than the other. This blade orientation might be evidence of an "anchor" blade that grew further into the microbial mat or sediment substrate to more effectively attach the organism in life; a less symmetrical position than the current "bathtub" or "canoe-shaped" model. Alternatively, it is possible that this suggests a more erect life position and that the "robust" blade has been folded and flattened due to burial processes.
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