Explaining the exceptional preservation of Ediacaran rangeomorphs from Spaniard's Bay, Newfoundland: A hydraulic model

Papers in Palaeontology

et al. 2018

Self Cite

The Ediacaran macrofossil Charnia masoni Ford is perhaps the most iconic member of the Rangeomorpha: a group of seemingly sessile, frondose organisms that dominates late Ediacaran benthic, deep‐marine fossil assemblages. Despite C. masoni exhibiting broad palaeogeographical and stratigraphical ranges, there have been few morphological studies that consider the variation observed among populations of specimens derived from multiple global localities. We present an analysis of C. masoni that evaluates specimens from the UK , Canada and Russia, representing the largest morphological study of this taxon to date. We describe substantial morphological variation within C. masoni and present a new morphological model for this species that has significant implications both for interpretation of rangeomorph architecture, and potentially for existing taxonomic schemes. Previous reconstructions of Charnia include assumptions regarding the presence of structures seen in other rangeomorphs (e.g. an internal stalk) and of homogeneity in higher order branch morphology; observations that are not borne out by our investigations. We describe variation in the morphology of third and fourth order branches, as well as variation in gross structure near the base of the frond. The diagnosis of Charnia masoni is emended to take account of these new features. These findings highlight the need for large‐scale analyses of rangeomorph morphology in order to better understand the biology of this long‐enigmatic group.

“…; though see Brasier et al . ). This structure could alternatively be interpreted as an artefact of dragging upon felling.…”

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Previous Workmentioning

confidence: 99%

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Anatomy of the Ediacaran rangeomorph Charnia masoni

Dunn

Papers in Palaeontology

et al. 2018

Self Cite

“…Taphonomic interference may include the local rotation of branches (Narbonne et al 2009), the deflation of individual branches (Brasier et al 2013), as well as the displacement of branch order of overlap for unconstrained branches. The fact that only branching characters consistent across a given specimen were included in the analyses presented here should minimize the influence of taphonomy on the branching characters in this study.…”

Section: Influence Of Taphonomymentioning

confidence: 99%

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

2017

Rangeomorphs from the Ediacaran of Avalonia are among the oldest known complex macrofossils and our understanding of their ecology, ontogeny and phylogenetic relationships relies on accurate and consistent classification. There are a number of disparate classification schemes for this group, which dominantly rely on a combination of their branching characters and shape metrics. Using multivariate statistical analyses and the diverse stemmed, multifoliate rangeomorphs in Charnwood Forest (UK), we assess the taxonomic usefulness of the suite of characters currently in use.

“…While this type of preservation has been reported from the Spaniard's Bay locality of Newfoundland ( Fig. 4; Narbonne, 2004), other authors have interpreted the taphonomic mode at that locality to be more akin to death-mask preservation, with the higher relief of the fossils attributable to their preservation within scours in the underlying bed (Brasier et al, 2013). Regardless, preservation on this bed is remarkable, and dependent on a unique (to date) combination of taphonomic circumstances; there may be as-yet undiscovered examples of this style of preservation.…”

Section: ! Upsides and Downsides: Moldic Preservationmentioning

confidence: 52%

Of Time and Taphonomy: Preservation in the Ediacaran

2014

Paleontol. Soc. pap.

The late Neoproterozoic witnessed a revolution in the history of life: the transition from a microbial world to the one known today. The enigmatic organisms of the Ediacaran hold the key to understanding the early evolution of metazoans and their ecology, and thus the basis of Phanerozoic life. Crucial to interpreting the information they divulge is a thorough understanding of their taphonomy: what is preserved, how it is preserved, and also what is not preserved. Fortunately, this Period is also recognized for its abundance of soft-tissue preservation, which is viewed through a wide variety of taphonomic windows. Some of these, such as pyritization and carbonaceous compression, are also present throughout the Phanerozoic, but the abundance and variety of moldic preservation of body fossils in siliciclastic settings is unique to the Ediacaran. In rare cases, one organism is preserved in several preservational styles which, in conjunction with an increased understanding of the taphonomic processes involved in each style, allow confident interpretations of aspects of the biology and ecology of the organisms preserved. Several groundbreaking advances in this field have been made since the 1990s, and have paved the way for increasingly thorough analyses and elegant interpretations.