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Mobergellans from the early Cambrian of Greenland and Labrador: new morphological details and implications for the functional morphology of mobergellans

Published online by Cambridge University Press:  29 August 2017

Christian B. Skovsted  and
Timothy P. Topper
Christian B. Skovsted
Affiliation:
Department of Palaeobiology, Swedish Museum of Natural History, Box 50007, SE-104 05 Stockholm, Sweden 〈christian.skovsted@nrm.se〉
Timothy P. Topper
Affiliation:
Palaeoecosystems Group, Department of Earth Sciences, Durham University, Durham DH1 3LE, UK 〈timothy.topper@durham.ac.uk〉
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Abstract

New morphological features of the mobergellan Discinella micans (Billings, 1871) from the lower Cambrian (Stage 4) of Northeast Greenland and southern Labrador are described. The new features include: (1) the morphology of the larval shell, which is shown to be cap-shaped, subcircular, and with impressions of the internal muscle attachment scars; (2) a range of unusual shell deformations (changes in growth direction resulting in thickened shells, partial detachment of shell laminae and subsequent regrowth, internal projections of shell material increasing the depth of the shell by up to 150%, disturbances and irregular fusion of muscle scars). In addition, we provide new details about the variability in number and shape of the anteriormost internal muscle scars, which often fuse and may vary in number from one to three (resulting in nine to 11 scars in total). Together the new observations provide additional strength for the hypothesis that mobergellan shells represent opercula of an as yet unknown tubular organism.

Type
Articles
Information
Journal of Paleontology , Volume 92 , Special Issue 1: Cambrian Explosion , January 2018 , pp. 71 - 79
Copyright
Copyright © 2017, The Paleontological Society 

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