Large, soft-bodied fronds were among the first large and complex creatures that evolved on our planet, and these fronds dominated the seas during the latter half of the Ediacaran Period (575–538 million years ago), which immediately preceded the Cambrian. Some of the first Ediacaran fronds described were found in the Flinders Ranges of Australia. A frond named Rangea longa by Martin Glaessner and Mary Wade in 1966, which was nearly half a meter long, is unique in almost always appearing on the top of the bed that contains it. The morphologies of the specimens they described were variable, which hindered global understanding of how many types were present and the time range that each morphology exhibited. Our study of all specimens ever discovered shows that Glaessner and Wade were correct in concluding that all these specimens belonged to the same species, and superb preservation of these fronds shows that the variation we see among these fossils reflects which side of the frond faced up and what angle it lay on the sea floor when it died. These fronds represent a new genus called Akrophyllas (literally “the frond on the top” in ancient Greek). Akrophyllas lived as an erect frond that was firmly anchored to the shallow sea floor by a bulbous holdfast, and died when it was buried by sand during a storm.

Decimeter-scale, elongate, fossil fronds from the Ediacara Range in South Australia were formally described as Rangea longa Glaessner and Wade, 1966, but the disparate nature of documented specimens has hindered their inclusion in global syntheses and has resulted in these fossils being assigned to at least five different genera in two different clades since their discovery. Detailed study of the type material from the Ediacara Range and the few specimens subsequently collected elsewhere in the Flinders Ranges reaffirms that these specimens represent a single species, with the apparent morphological variation between specimens entirely taphonomic and reflecting the obverse and reverse surfaces of these fronds coupled with the orientation of the frond axis and petaloids at different angles relative to the sea bottom on which they were preserved. The preserved architecture of these fronds constitutes three orders of branching microstructure that are strictly orthogonal to immediately higher and lower orders. This implies affinities with the arboreomorphs, but representing a new frond genus herein named Akrophyllas. Akrophyllas n. gen. differs from all other Ediacaran fronds in exhibiting a stalk that is visible only on one side of the frond and is internal to the other side where the first-order branches instead meet at a zigzag axial trace. Akrophyllas n. gen. was attached to a bulbous holdfast on the sea bottom, and evidence for current scours that formed in the lee of the fronds and for a strong current alignment of felled fronds with depositional overlap of adjacent fronds imply an upright, epibenthic lifestyle for Akrophyllas longa new combination.