Palaeobiology of the reclining rangeomorph Beothukis from the Ediacaran Mistaken Point Formation of southeastern Newfoundland

• Published in: Geological Magazine
• Main Authors: McIlroy, Duncan, Hawco, Jessica, McKean, Christopher, Nicholls, Robert, Pasinetti, Giovanni, Taylor, Rod
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2020
• Subjects: Newfoundland
• Online Access: http://dx.doi.org/10.1017/s0016756820000941; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756820000941

Abstract Beothukis mistakensis from the Ediacaran System of Newfoundland, Canada demonstrates complex fractal-like morphology through the development of primary-, secondary- and tertiary-order Rangea-like units. The primary-order rangeomorph units observed in B. mistakensis are tightly juxtaposed, show no evidence of being independent of one another and are made up of chamber-like secondary-order – probably mesoglea-filled – units. The growth of these rangeomorph units demonstrates that the frond developed from the tip towards the basal region through ontogeny. The tertiary-order units of Beothukis are considered to represent surface morphology on the secondary-order units. This is in contrast to palaeobiological reconstructions of Beothukis that invoke three-dimensional fractal-like branches with independent units, which has been used to infer an osmotrophic mode of life. It is considered here that the fractal-like morphology of the lower surface of B. mistakensis was an adaptation to increase surface area to volume ratio. The quilted morphology of Beothukis proposed here is consistent with a sessile, reclining, phagocytotic and/or chemosymbiotic mode of life similar to that invoked for the reclining rangeomorph Fractofusus .