Morphometrics and orientation of Fractofusus dominated assemblages from the Ediacaran of Newfoundland

Neville, Jenna (2023) Morphometrics and orientation of Fractofusus dominated assemblages from the Ediacaran of Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

The rangeomorph genus Fractofusus inhabited marine benthic environments during the Ediacaran period. These frondlike organisms with fractal-like branching are believed to be among the earliest multicellular animals. Studying their paleobiology, paleoecology and interactions with their paleoenvironment is crucial for understanding early animal evolution. This study compared morphometric and orientation data of Fractofusus misrai (from Mistaken Point, NL) and Fractofusus andersoni (from Little Catalina, NL) in order to better understand population structure and paleoecology. Statistical analyses were conducted to infer size and shape classes, and to determine any significant orientation differences between the shape groups. This work indicates that the F. misrai assemblage on the E surface likely resulted from aseasonal continuous reproduction following a single spatfall event while the F. andersoni assemblage on the H14 surface is comprised of two spatfall events. Previous studies have suggested that Fractofusus is randomly oriented, key evidence used to infer a reclining mode of life. This study has revealed orientation trends based on shape, with proportionally wider specimens oriented to the southeast and more elongated specimens being oriented towards the northeast. These findings suggest that some aspect of the paleobiology of Fractofusus may have been controlled by current-related phenomena (possibly oxygen or nutrient capture).

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