Ediacaran metazoan fossils with siliceous skeletons from the Digermulen Peninsula of Arctic Norway

Małgorzata Moczydłowska,Peter Lazor,Jarosław Majka,Daniel Snitting,Lei Liu,Benjamin P Kear

doi:10.1017/jpa.2020.105

Małgorzata Moczydłowska, Peter Lazor + Show 4 more

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https://doi.org/10.1017/jpa.2020.105

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Abstract

AbstractIn this study, a new assemblage of Ediacaran metazoan fossils is reported from the basal Stáhpogieddi Formation on the Digermulen Peninsula of Arctic Norway, includingAnulitubusn. gen. Moczydłowska in Moczydłowska et al.,Anulitubus formosusn. gen. n. sp. Moczydłowska in Moczydłowska et al.,Coniculusn. gen. Moczydłowska in Moczydłowska et al.,Coniculus elegantisn. gen. n. sp. Moczydłowska in Moczydłowska et al.,Fistulan. gen. Moczydłowska in Moczydłowska et al., andFistula crenulatan. gen. n. sp. Moczydłowska in Moczydłowska et al. The specimens are three-dimensionally preserved and include tubular and conical skeletons that are morphologically distinguished by their body-wall constructions, radial symmetry, polarity, segmentation, and annulation. The skeletons are interpreted to be biomineralized by primary silica based on computed micro-tomographic, petrographic, geochemical, and spectroscopic evidence of originally rigid body wall with layers of constant thicknesses, composed of opal, microcrystalline quartz, and an admixture of carbonaceous material, which differ from the host sediment mineralogy and do not show replacement or encrustation. The fossil-bearing interval immediately overlies strata of Gaskiers age and can be bracketed within 580–541 Ma, but it is estimated to be ca. 575 Ma on the basis of averaged sedimentation rates and biostratigraphic correlations with Ediacaran biota found in up-section deposits of ca. 558–555 Ma. Future new findings of such fossils in different preservation modes and further multi-collector inductively coupled plasma mass spectrometry, which shows the silicon fractionation and traces its biogenic origin versus inorganic mineralization, may corroborate the interpretation of biogenic silicification of these earliest skeletal fossils.UUID:https://zoobank.org/6bccada1-870e-47b0-b819-82685152ea54

Highlights

The early evolution of animals, or metazoans (Metazoa), can be traced back to the Ediacaran Period (635–541 Ma) based on the fossil record of macroscopic soft-bodied impressions, carbonaceous compressions, and subsequently mineralized and organically preserved organisms (Narbonne, 2005; Moczydłowska et al, 2014; Wan et al, 2016; Xiao et al, 2016; Schiffbauer et al, 2020)
Abstract.—In this study, a new assemblage of Ediacaran metazoan fossils is reported from the basal Stáhpogieddi Formation on the Digermulen Peninsula of Arctic Norway, including Anulitubus n. gen
The skeletons are interpreted to be biomineralized by primary silica based on computed micro-tomographic, petrographic, geochemical, and spectroscopic evidence of originally rigid body wall with layers of constant thicknesses, composed of opal, microcrystalline quartz, and an admixture of carbonaceous material, which differ from the host sediment mineralogy and do not show replacement or encrustation

Summary

Introduction

The early evolution of animals, or metazoans (Metazoa), can be traced back to the Ediacaran Period (635–541 Ma) based on the fossil record of macroscopic soft-bodied impressions, carbonaceous compressions, and subsequently mineralized and organically preserved organisms (Narbonne, 2005; Moczydłowska et al, 2014; Wan et al, 2016; Xiao et al, 2016; Schiffbauer et al, 2020). The Ediacaran fossil ranges and chronostratigraphy.—The Ediacaran soft-bodied macroscopic impression taxa (some known from 3-D casts and molds in other occurrences), including Dickinsonia, Swartpuntia, Hiemalora, and Aspidella, and 3-D preserved Palaeopascichnus are recorded in the Stáhpogieddi Formation (Fig. 2) Their first appearance datum (FAD), last appearance datum (LAD), and stratigraphic ranges are established from global records and used for our estimation of the age of the assemblage containing them on the Digermulen Peninsula. Based on the current recognition of stratigraphic ranges in isotopically dated sedimentary intervals containing the fossils, the overlapping ranges of Aspidella, Hiemalora, Dickinsonia, and Swartpuntia at 558–555 Ma provide the closest available age that is inferred for the strata recording these taxa in the Stáhpogieddi Formation (Fig. 2). The average rate of deposition may be considered here as reliable

Materials and methods

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Conclusions