Paleobiology and Taphonomy of Exceptionally Preserved Putative Macroalgae from the Ediacaran Zuun-Arts Biota, Zavkhan Province, Mongolia

Abstract

The first unequivocal evidence of complex multicellular life appears in exceptionally preserved Ediacaran (635-541 Ma) fossil deposits. The newly discovered Ediacaran Burgess Shale-type (BST) Zuun-Arts Biota of Zavkhan Province, Mongolia, contains putative macroalgae fossils. Morphological measurements of 821 individual specimens including length, width, and branching angle obtained using ImageJ software were used to calculate morphological parameters including median thallus length (16.75 mm), filament width (0.50 mm), branching angle (63.63⁰), and surface area/volume ratio (8.19 mm -1). The Zuun-Arts biota contains fossils of six distinct morphotypes: non-branching, dichotomous branching, monopodial branching, fan-shaped, shrub-like, and small non-branching, all morphologies are similar to macroalgae from the Ediacaran Lantian and Miaohe biotas. Morphological and taphonomic data rule out a non-macroalgae affinity, and SEM-EDS data indicate that the Zuun-Arts fossils are preserved as aluminosilicate and carbon films. Results indicate that the Zuun-Arts fossils are macroalgae preserved as aluminosilicate mineral films.