A new species of stalked crinoid (Echinodermata) of possible Late Silurian age from central Newfoundland

Authors

  • S. K. Donovan Department of Geology, University of the West Indies, Mona, Kingston 7, Jamaica
  • W. L. Dickson Geological Survey, Newfoundland and Labrador Department of Mines and Energy, P. O. Box 8700, St. Johns, Newfoundland A IB 4J6, Canada
  • W. D. Boyce Geological Survey, Newfoundland and Labrador Department of Mines and Energy, P. O. Box 8700, St. Johns, Newfoundland A IB 4J6, Canada
  • J. S. Ash Geological Survey, Newfoundland and Labrador Department of Mines and Energy, P. O. Box 8700, St. Johns, Newfoundland A IB 4J6, Canada

DOI:

https://doi.org/10.4138/2055

Abstract

A new fossil locality within a sequence previously assigned to the Middle Ordovician Baie D'Espoir Group in south-central Newfoundland contains fragmented crinoid columnals and brachiopods. Distinctive, pentastellate crinoid columnals, similar to those assigned to the monobathrid camerate Hexacrinites Austin and Austin by Russian authors, are named Hexacrinites? Pentastellatus n. sp. Nodal(?) columnals of this species have a circular, depressed articular facet, with a conical to bowl-like crenularium, a depressed, circular areola, a raised perilumen and a short, slender axial canal of pentagonal section. The oldest Hexacrinites sensu stricto are Late Silurian, suggesting that the fossiliferous strata have been incorrectly assigned to the Ordovician. Cross-sections of brachiopods from the same locality include an example that resembles several Early Silurian to Late Devonian pentameroid genera including Brooksina Kirk, 1922. Correlation with Late Silurian, bivalve-bearing strata SO km to the northeast would indicate that a major unconformity may occur above the fossiliferous Early and Middle Ordovician strata and the Early Ordovician ophiolite complexes. RÉSUMÉ Un nouvel emplacement de fossiles à I'intérieur d'une sequence auparavant attribute au groupe de l'Ordovicien moyen de Baie d'Espoir dans le centre-sud de Terre-Neuve renferme des fragments de columnales et de brachiopodes de crinoldes. Des columnales de crinoldes pentaétoilées caractéristiqucs, semblables à celles attributées à l’Hexacrinites Austin and Austin à loges monobathrides par des auteurs russes, sont baptisées nouvelle espèce pentastellatus d'Hexacrinites?. Les columnales nodales(?) de cette espèce sont pourvues d'une facette articulaire renfoncée et circulaire munie d'un crenularium allant de conique à bombé, d'une aréole circulaire renfoncie, d'un périlumen surélevé et d'un canal axial mince et court de section pentagonalc. Les plus anciens Hexacrinites, au sens strict, remontent au Silurien supérieur, ce qui permet de supposer qu'on a incorrectement attribué la strate fossilifère à l'Ordovicien. Des iéchantillons représentatifs de brachiopodes du même emplacement comprennent un exemple qui ressemble à plusieurs genres de pentaméroides datant du Silurien inférieur au Dévonien supérieur, notamment le Brooksina Kirk, 1922. Leur corrélation avec des strates renfermant des bivalves du Silurien supérieur à 50 km au nord-cst signale qu'une discordance importantc pourrait se présenter au-dessus des strates fossiliferes de l'Ordovicien inférieur ou moyen de même que des complexes d'ophiolites de l'Ordovicien inférieur. [Traduit par la rédaction]

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Published

1997-04-01

How to Cite

Donovan, S. K., Dickson, W. L., Boyce, W. D., & Ash, J. S. (1997). A new species of stalked crinoid (Echinodermata) of possible Late Silurian age from central Newfoundland. Atlantic Geoscience, 33(1). https://doi.org/10.4138/2055

Issue

Vol. 33 No. 1 (1997)

Section

Articles

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