The Beothukis/Culmofrons problem and its bearing on Ediacaran macrofossil taxonomy: evidence from an exceptional new fossil locality

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms (Fig. 3A); rare Fractofusus andersoni Gehling and Narbonne, 2007 (Fig. 3C) branching (e.g. Fig. 2C; Supp. Fig. 5), whereas other notable fossil surfaces in Newfoundland 125 typically preserve only two or three. In addition to taxa assignable to known late Ediacaran 126 genera, a dense fabric of 100s of thin filamentous impressions is also present (Fig. 3E)

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

“…The argument that generic level diagnoses should be based on categorical characters, such as branching architecture, and that continuous characters should be used for species level diagnoses rests on the inference that categorical characters dominantly reflect a genetic control, whereas continuous characters, such as stem length, are more susceptible to environmental influences and, potentially, to ecophenotypic variability and convergence (Liu et al 2016). If aspects of branching architecture can be influenced or modified by the environment to the same extent as continuous characters, then this inference would break down.…”

“…Equally, although the overall morphology can differentiate forms above the species level (Hoyal Cuthill & Conway Morris 2014), shape metrics are not easily transferred between different tectonic settings. Liu et al (2016) have argued that categorical characters are more appropriate to genus-level diagnoses and that continuous characters should be restricted to differentiating species. This was based on the inference that the branching architecture reflects genetic controls and that shape metrics are more susceptible to environmental influences (and thus convergence), which relies on the consistency of branching between multiple specimens.…”

“…Current taxonomic frameworks for rangeomorphs place the greatest weight on one of the two main sources of available characters: (1) categorical characters, such as a branching architecture (see Fig. 2b; see Supplementary material table 1 for a full description of characters), the presence/ absence of a holdfast and the number of growth poles (Brasier & Antcliffe 2009;Narbonne et al 2009;Brasier et al 2012;Laflamme et al 2012;Liu et al 2016); and (2) continuous characters (see Fig. 2a), such as shape metrics (length to width ratios) and their overall morphology (Laflamme et al 2004;Laflamme & Narbonne 2008).…”

Ediacaran pre-placozoan diploblasts in the Avalonian biota: the role of chemosynthesis in the evolution of early animal life

“…The majority of the Avalonian macrobiota is represented by non-mineralized epibenthic macro-organisms, which, even in the oldest fossiliferous strata, grew to up to 1 m in length or 20 cm in diameter Liu et al 2011Liu et al , 2016Fig. 1a, b).…”

Post-fossilization processes and their implications for understanding Ediacaran macrofossil assemblages

“…'Charnia Type A', as identified in that study, included specimens now assigned to Charnia masoni (Ford 1958), Vinlandia antecedens (Laflamme et al 2007;Brasier et al 2012) and Beothukis mistakensis (Brasier & Antcliffe 2009). 'Charnia Type B' included Trepassia (previously Charnia) wardae ) and Beothukis (formerly Culmofrons) plumosa Liu et al 2016). In addition, some Beothukis plumosa were considered as 'Charnia Type A' rather than 'Charnia Type B' Laflamme Fig.…”