UC Riverside

The earliest fossil evidence for complex, macroscopic, community forming organisms on Earth is preserved in the Ediacara biota (575—538 Ma). While placement of Ediacaran taxa within a phylogenetic framework is difficult due to their unique morphologies that are non-analogous to the definitive metazoans of the Phanerozoic, they can be categorized into grades based on body plan similarity, resulting in suites of morphologically similar, but not necessarily phylogenetically related, taxa known as morphogroups. The tubular morphogroup includes all macroscopic, metazoan-grade organisms with hollow and elongate morphologies and is one of the most commonly occurring Ediacaran morphogroups, suggesting that a tubular form was an advantageous morphology for early complex organisms. However, the nature of this advantage is unknown and untestable due to insufficient baseline understanding of the number of genera included in the morphogroup, their temporal ranges, as well as their paleobiological traits and paleoecological strategies. This dissertation develops a foundational understanding of these questions pertaining to the tubular morphogroup through database generation and analysis, detailed taphonomic investigation, and analysis of growth strategies. Synthesis of the global record of the Ediacaran tubular morphogroup demonstrates that they are the most diverse Ediacaran morphogroup and were key components of Ediacaran ecosystems for ~20 million years longer than was previously appreciated. Detailed taphonomic investigation of the tubular organism Aulozoon soliorum from the Ediacara Member of South Australia provides novel insight into the morphology, biomaterials, and paleoecology of this taxon as well as develops a methodology for distinguishing between true morphological features and taphonomically-derived features that that can be leveraged for investigation of other tubular taxa. Study of the growth strategies of the tubular organism Funisia dorothea from the Ediacara Member of South Australia demonstrates that, despite a broadly simple form, Funisia’s growth was highly regulated. Additionally, comparison of Funisia’s growth strategies with another tubular organism, Wutubus annularis, reveals that shared morphology of tubular organisms does not beget developmental or paleoecological similarity. Ultimately, this research develops understanding of what genera, paleoecological strategies, and paleobiological traits are encompassed by the tubular morphogroup and provides novel frameworks for the identification of paleobiologically and paleoecologically meaningful characteristics of individual tubular genera.