Charnia

Abstract: Newly discovered fronds of the Ediacaran index fossil Charnia from the Drook Formation of southeastern Newfoundland are the oldest large, architecturally complex fossils known anywhere. Two species are present: Charnia masoni , originally described from Charnwood Forest in central England and now known worldwide, may have ranged through as much as 30 m.y. of Ediacaran time, and C. wardi sp. nov., a new species of Charnia that consists of slender fronds to nearly 2 m in length, is the longest Ediacaran fossil yet described anywhere. These fossils, which are present midway between the glacial diamictites of the Gaskiers Formation (ca. 595 Ma) and the classic Ediacaran assemblage of the Mistaken Point Formation (565 ± 3 Ma) 1500 m higher in the same section, provide our first glimpse of complex megascopic life after the meltdown of the “snowball Earth” glaciers.

Abstract: Newly discovered, exceptionally preserved, soft-bodied fossils near Spaniard9s Bay in eastern Newfoundland exhibit features not previously described from Ediacaran (terminal Neoproterozoic) fossils. All of the Spaniard9s Bay taxa were composed of similar architectural elements—centimeter-scale frondlets exhibiting three orders of fracticality in branching. Frondlets were combined as modules atop semi-rigid organic skeletons to form a wide array of larger constructions, including frondose and plumose structures. This architecture and construction define the “rangeomorphs,” a biological clade that dominated the Mistaken Point assemblage (575 to 560 million years ago) but does not appear to be ancestral to any Phanerozoic or modern organisms.

Abstract: SYNOPSIS. The ‘‘Ediacaran organisms,’’ which preceded and overlapped the Cambrian radiation of metazoans, include many fossils whose systematic positions remain contentious after over fifty years of study. It might seem that nothing particularly useful can be learned from a biota full of oddballs. However, analyses of the distribution of the Ediacaran organisms in time and space can be carried out without having to guess at the systematic position of the organisms. Combining these results with data on paleotectonics, paleoenvironmental parameters, and the ages of various assemblages sheds light on the origins, ecology, and even the systematic positions of the Ediacaran organisms. Parsimony Analysis of Endemism (PAE) confirms earlier studies in grouping Ediacaran biotas into three major clusters: the Avalon, White Sea, and Nama Assemblages. The available radiometric and stratigraphic data suggest that the Avalon is the oldest, the White Sea is next oldest, and the Nama extends to the base of the Cambrian. The ‘‘frondlike’’ Ediacaran taxa, and to a lesser extent the ‘‘medusoids,’’ collectively show significantly longer stratigraphic ranges, broader geographical and paleoenvironmental ranges, and less provinciality than ‘‘bilaterian’’ and tubular taxa. Almost all tubular Ediacarans appear to be confined to equatorial areas, whereas other Ediacaran organisms show weak or no latitudinal diversity gradients. I conclude that the Ediacaran organisms show a diverse range of responses to various environmental parameters. There is no basis for classifying them all as having a single body plan and mode of life, as has often been done in the past.

Abstract: Summary Several specimens of two new fossils recently found in the Woodhouse Beds of the Charnwood Forest Pre-Cambrian succession are described and named Charnia masoni and Charniodiscus concentricus. Their possible association as parts of a single organism is discussed and comparisons are drawn with some other Pre-Cambrian fossils in an attempt to establish their biological status. The evidence points to their being algae.