RELATING EDIACARAN FRONDS

Ediacaran fronds are an important component of terminal-Proterozoic (Ediacaran – 579-541 Ma) ecosystems; they are amongst the most recognizable, widespread and common body forms amongst the Ediacara biota ranging across all major faunal localities and time slices postdating the Gaskiers Glaciation. The importance of the frond morphology is evident, as no fewer than three distinct groups of Ediacaran organisms (i.e. the Arboreomorpha, Erniettomorpha and Rangeomorpha) have independently evolved this mode of elevating a feeding structure higher into the water column. Despite their ubiquity, questions still exist over issues of homology and functional morphology between, and within, purported “clades”. A new cladistics analysis of the Arboreomorpha, Erniettomorpha and Rangeomorpha has been conducted, incorporating architectural, developmental, and structural characters to illuminate the evolutionary history of these groups. Through this study, it is possible to understand the pattern of evolution within, and between, these clades, including the identification of homoplasies, functional constraints, and ectomorphs. Ultimately, this study both validates previous studies of Ediacaran “clades”, and accentuates instances where previous assumptions of their natural history is no longer warranted.