COMPLEX MULTIFOLIATE EDIACARAN FRONDS FROM MISTAKEN POINT NEWFOUNDLAND, CANADA

Among the myriad of highly ornamented Precambrian Ediacara Biota, the rangeomorphs constitute the most complex bauplan, due in part to their innate “fractal quilting” that highlights a repetitive pattern that is identical over at least three orders of branching. The “fractal quilting” of Ediacaran rangeomorphs (ca. 575-543 Ma) showcase an alternative to modern animal construction, despite sharing key ecological properties allowing rangeomorphs to construct and manage modern-style ecosystems prior to the Cambrian. Rangeomorphs have a worldwide distribution, with known examples from Australia, Russia, Namibia, England, and most notably from Mistaken Point Newfoundland, where they constitute the overwhelming majority of the diversity and abundance of the Ediacaran Biota present. Within the diversity of forms, the upper tier epifaunal fronds are characterized by complex, multifoliate (i.e. several independent leaves which radiate from the central stalk) petaloids composed of several, independent and unconstrained primary rangeomorph branches each housing a series of independent rangeomorph frondlets and anchored to the substrate by a basal, possibly buried, holdfast. Their morphology is complicated by taphonomic properties which have, until now, hidden the original three-dimensional shape. Overlapping branching relationships and internal structures are rarely (if ever) preserved in nearly two-dimensional surface impressions, resulting in these organisms being reconstructed as oversimplified “carpet” or “sheet-like” forms. Through detailed photography and morphometric analyses of numerous complete rangeomorph specimens preserved in various mediums, these preservational biases can be removed. Specimens of a new species of Ediacaran rangeomorph frond preserved in thin and thick ash (two different types of Conception-style positive epirelief preservation) from Mistaken Point, in addition to previously unknown specimens preserved in Flinders-style positive hyporelief from the Sheepbed Fm. of Northwester Canada, finally allow for the unique opportunity to compare morphological similarities in the same species across several different preservational mediums. The end result is a detailed reconstruction of one of the most morphologically complex Ediacaran fronds yet described.