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Enigmatic fossil encrusting an Upper Ordovician rocky shore on Hudson Bay, Canada

Published online by Cambridge University Press:  14 July 2015

Markes E. Johnson
Affiliation:
1Department of Geosciences, Williams College, Williamstown, Massachusetts 01267
Mu Xi-Nan
Affiliation:
2Nanjing Institute of Geology and Palaeontology, Academia Sinica, Nanjing 210008, China ,
Rong Jia-Yu
Affiliation:
2Nanjing Institute of Geology and Palaeontology, Academia Sinica, Nanjing 210008, China ,

Abstract

Storeacolumnella hudsonensis is described as a new genus and species of encrusting, colonial organism that lived in an intertidal, rocky-shore environment. The fossil was discovered in the basal beds of the Upper Ordovician Port Nelson Formation at a coastal outcrop on Hudson Bay near Churchill, Manitoba. Showing some possible characteristics of sponges and other possible characteristics of calcaerous green algae, this matlike organism is considered nonetheless to have uncertain taxonomic affinities. It consists of cylinder-shaped columns, each with an internal system of star-shaped filaments or spicules as viewed in transverse section. The cylinders stand vertical in longitudinal section and are densely packed together to form a mat. The hard substrate to which the mat is attached consists of a boulder eroded from the Precambrian Churchill Quartzite. Maximum colony size observed in a single example exhibits a diameter of not less than 80 mm and maximum thickness of 5.85 mm.

Type
Research Article
Copyright
Copyright © The Paleontological Society 

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