Spatial analysis of Beltanelliformis (Nemiana) in Baltica

Discoidal fossils are some of the most abundant and widespread Ediacaran taxa found in many different environments throughout the late Ediacaran (580–539 Ma). They have a wide range of suggested affinities including microbial colonies, medusae, and the holdfasts of frondose taxa, including putative algal/bacterial discoidal taxa, such as Beltanelliformis and Nemiana, which are often found in large abundance in monospecific clusters. From their spatial patterns, we can infer the underlying biological and ecological processes governing their community ecology. Here, we analyzed four new Ediacaran communities from the ca. 567–539 Ma Moldova-Podillya Basin, with Vălcineț Area A and B, in the nearshore to shallow-marine environments, Cosăuți in the lower-energy marine environment, and Egoreni in the shallow-marine conditions (2352 specimens over 11.46 m2), as well as previously described two communities (196 specimens over 1.80 m2) from Kolesnikov (2022) data and 121 specimens over 0.46 m2 from Leonov (2007) data from the Central Urals and the White Sea areas, respectively. These communities exhibited different community dynamics, with strong cluster orientation and dispersal processes in the Vălcineț and South Urals communities, in contrast to the strong association with habitat patchiness for the Cosăuți, Egoreni and White Sea area communities. Our results suggest two alternative drivers for Beltanelliformis communities, those controlled by dispersal in currents and those in a weaker flow by substrate patchiness. The White Sea assemblage Ediacaran biota show variation in environmental and dispersal dynamics and thus contrast with Avalonian assemblage Ediacaran biota, which show consistent drivers across large spatial and temporal scales.