DIVERSITY IN THE AGE OF TUBES: A MORPHOMETRIC APPROACH TO UNDERSTANDING THE BREADTH OF EDIACARAN TUBE-DWELLING TAXA

The closing 10–15 million years of the Ediacaran Period hosts a diversity of tubicolous fossil organisms. Some of these tubes were composed of biominerals, representing the first metazoan-grade biomineralization in the fossil record, while others are inferred to have had an originally organic composition. Assemblages of tubicolous organisms were cosmopolitan in the terminal Ediacaran, with evidence of their global distribution found in deposits of Brazil, China, eastern Europe, Kazakhstan, Iran, Mexico, Mongolia, Namibia, Oman, Paraguay, Siberia, Spain, and the United States. Accordingly, pending efforts to subdivide the Ediacaran Period into internationally recognized Stage-level divisions have begun to home in on the plentiful record of these organisms in reference to defining the terminal stage. However, their taxonomic, taphonomic, and paleoenvironmental ranges are notably variable, imparting difficulties on such efforts—as well as truly understanding their phyletic diversity, especially since nearly all of them are without any semblance of preservation of the organism that once lived within the tube. Here, after construction of an extensive dataset of the prevalent fauna of the age of tubes, we explore multivariate approaches (such as non-metric multidimensional scaling, NMDS) to examine trends in their morphology. We hope that this approach provides a first step towards a better understanding of the complex relationships of these tubicolous organisms, the structure of their ecosystems, and ultimately the roles they may have played during the dawn of the eumetazoans.