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What does Ophiomorpha irregulaire really look like?

Leaman, M.; McIlroy, D.; Herringshaw, L.G.; Boyd, C.; Callow, R.H.T.

Authors

M. Leaman

D. McIlroy

Dr Liam Herringshaw L.Herringshaw@hull.ac.uk
Lecturer in Geology / Director of Admissions for Geography, Geology & Environment

C. Boyd

R.H.T. Callow



Abstract

Ophiomorpha irregulaire is a surprisingly poorly characterised ichnotaxon given its common occurrence in hydrocarbon reservoir facies. Current debate surrounds the ichnotaxobases suitable for ichnospecific-level identification and also the palaeogeographic distribution of the taxon. O. irregulaire is conventionally characterised in core by the presence of “spikey”, fine-grained, wall-lining pellets, since the horizontal “meander maze” that is also part of the ichnospecific diagnosis cannot normally be demonstrated. To resolve ichnotaxonomic issues concerning the validity of pellet morphology as a primary ichnotaxobase, material from the type locality is re-described (Cretaceous Book Cliffs, Utah), with an emphasis on burrow wall morphology. Comparative neoichnological studies using the callianassid crustacean Neotrypaea californiensis were additionally conducted to understand the behaviour of modern taxa that produce burrows closely resembling O. irregulaire. High-resolution, three-dimensional morphological models were created from specimens of Ophiomorpha from the type locality of O. irregulaire in Utah, USA, and from Eocene deep marine turbidites of the Juncal Formation, California. Comparison of the morphological features from these two localities, as well as specimens observed in core from offshore Newfoundland, demonstrate conclusively that O. irregulaire is not restricted to the Cretaceous Western Interior Seaway. O. irregulaire may have a stratigraphic range from Jurassic to Recent, and occur in palaeoenvironmental settings ranging from shallow marine to continental slope settings. The flame-like pellet morphology is considered characteristic of the type material, and is a valid criterion for identifying O. irregulaire in core.

Journal Article Type Article
Publication Date 2015-12
Journal Palaeogeography, Palaeoclimatology, Palaeoecology
Print ISSN 0031-0182
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 439
Pages 38-49
APA6 Citation Leaman, M., McIlroy, D., Herringshaw, L., Boyd, C., & Callow, R. (2015). What does Ophiomorpha irregulaire really look like?. Palaeogeography, palaeoclimatology, palaeoecology, 439, 38-49. doi:10.1016/j.palaeo.2015.01.022
DOI https://doi.org/10.1016/j.palaeo.2015.01.022
Keywords Earth-Surface Processes; Palaeontology; Ecology, Evolution, Behavior and Systematics; Oceanography
Publisher URL https://www.sciencedirect.com/science/article/pii/S0031018215000401?via%3Dihub
Additional Information This article is maintained by: Elsevier; Article Title: What does Ophiomorpha irregulaire really look like?; Journal Title: Palaeogeography, Palaeoclimatology, Palaeoecology; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.palaeo.2015.01.022; Content Type: article; Copyright: Copyright © 2015 Elsevier B.V. All rights reserved.