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Engineering the Cambrian explosion: the earliest bioturbators as ecosystem engineers

Herringshaw, Liam G.; Callow, Richard H. T.; McIlroy, Duncan

Authors

Duncan McIlroy

Dr Liam Herringshaw L.Herringshaw@hull.ac.uk
Lecturer in Geology / Deputy Director of Admissions (Geology / Geography)

Richard H. T. Callow

Richard H.T. Callow

Abstract

By applying modern biological criteria to trace fossil types and assessing burrow morphology, complexity, depth, potential burrow function and the likelihood of bioirrigation, we assign ecosystem engineering impact (EEI) values to the key ichnotaxa in the lowermost Cambrian (Fortunian). Surface traces such as Monomorphichnus have minimal impact on sediment properties and have very low EEI values; quasi-infaunal traces of organisms that were surficial modifiers or biodiffusors, such as Planolites, have moderate EEI values; and deeper infaunal, gallery biodiffusive or upward-conveying/downward-conveying traces, such as Teichichnus and Gyrolithes, have the highest EEI values. The key Cambrian ichnotaxon Treptichnus pedum has a moderate to high EEI value, depending on its functional interpretation. Most of the major functional groups of modern bioturbators are found to have evolved during the earliest Cambrian, including burrow types that are highly likely to have been bioirrigated. In fine-grained (or microbially bound) sedimentary environments, trace-makers of bioirrigated burrows would have had a particularly significant impact, generating advective fluid flow within the sediment for the first time, in marked contrast with the otherwise diffusive porewater systems of the Proterozoic. This innovation is likely to have created significant ecospace and engineered fundamentally new infaunal environments for macrobiotic and microbiotic organisms alike.

Journal Article Type Article
Publication Date 2017
Journal Geological society special publications
Print ISSN 0305-8719
Electronic ISSN 2041-4927
Publisher Geological Society
Peer Reviewed Peer Reviewed
Volume 448
Issue 1
Pages 369-382
Book Title Geological Society Special Publication
DOI https://doi.org/10.1144/sp448.18
Keywords Geology; Ocean Engineering; Water Science and Technology
Publisher URL http://sp.lyellcollection.org/content/early/2017/01/20/SP448.18.abstract
Additional Information This is a copy of an article published in: Geological society special publications, 2017, v.448.

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