A rich Ediacaran assemblage from eastern Avalonia: Evidence of early widespread diversity in the deep ocean

Abstract

The Avalon Assemblage (Ediacaran, late Neoproterozoic) provides some of the oldest evidence of diverse macroscopic life and underpins current understanding of the early evolution of epibenthic communities. However, its overall diversity and provincial variability are poorly constrained and are based largely on biotas preserved in Newfoundland, Canada. We report coeval high-diversity biotas from Charnwood Forest, UK, which share at least 60% of their genera in common with ones in Newfoundland. This indicates that substantial taxonomic exchange took place between different regions of Avalonia, probably facilitated by ocean currents, and suggests that a diverse deepwater biota may already have been widespread at the time. Contrasts in the relative abundance of prostrate versus erect taxa likely record differential sensitivity to physical environmental parameters (hydrodynamic regime, substrate) and highlight their significance in controlling community structure.

New perspectives on the globally important Ediacaran fossil discoveries in Charnwood Forest, UK: prequel to

“…This is within the error limits of a U-Pb zircon age of 565 ± 3 Ma (Benus 1988) for the Ediacaran fossil horizon at Mistaken Point in Newfoundland, with which the Charnian 'Mercian Assemblage' of fossils is closely comparable (Wilby et al 2011).…”

“…Recent findings summarised in Wilby et al (2011) confirm that these impressions vary greatly in size, and among them the most obvious are three large (30-40 cm diameter), multi-ringed structures (e.g. Fig.…”

“…Boynton & Ford 1995 and references therein;Ford 1963; and hundreds of new specimens have recently been discovered (Wilby et al 2011) in what had previously been regarded as a sparse assemblage, promising a renaissance of ideas about the earliest diverse macroscopic life-forms to inhabit the planet.…”

Rangeomorph classification schemes and intra-specific variation: are all characters created equal?

“…1) are abundantly preserved on Bed B in Charnwood Forest (Wilby et al 2011;n ¼ 64). They are all oriented in the same direction (s ¼ 158), suggesting that they were felled and covered by the same event bed and, as such, will have experienced similar flow and burial conditions and the same tectonic processes.…”

“…Herein, we use multivariate statistical analysis to test the extent to which branching characters correlate with continuous morphological characters and to assess which characters are most taxonomically useful. Our analyses use the abundant and well-preserved assemblage of multifoliate, stemmed rangeomorphs present on Bed B in Charnwood Forest (Wilby et al 2011;Fig. 1).…”