An Ichnotaxonomic Approach to Wrinkled Microbially Induced Sedimentary Structures

ABSTRACT

Microbially induced sedimentary structures (MISS) are an important facet of recent paleoichnological work because of their taphonomic implications. MISS are extensively studied in terms of their formation processes, recognition in the ancient record, and their diverse morphologies. Classification and terminology schemes are based on their appearance and mode of formation; however, the taxonomic treatment of MISS remains debated. Traditionally MISS have been considered sedimentary structures, and arguments have been made that they cannot be treated as trace fossils under the International Code of Zoological Nomenclature (ICZN) due to MISS being formed by communities of microbiota including algae, cyanobacteria, and others, rather than a single tracemaker. Here, we reexamine MISS using an ichnotaxonomic approach and apply ichnologic terminology and binomial names. Upon reexamining the holotype of Kinneyia Walcott, a genus commonly used to describe some MISS, we argue it cannot be used to correctly describe wrinkle or ripple-like features seen in MISS, and we agree with previous authors that Kinneyia is likely not biogenic in origin. We here assign a new ichnogenus and ichnospecies, Rugalichnus matthewii, to ripple-like sedimentary wrinkle marks known as MISS, separating them from the nomen dubium genus Kinneyia.

KEYWORDS:

• Microbial mat
• Kinneyia
• Runzelmarken
• wrinkle ridges
• Saint John Group

Acknowledgments

The authors thank W. DiMichele (Smithsonian Institution) for providing photographs of Walcott's holotype of Kinneyia simulans, D. Rudkin (Royal Ontario Museum) for photographs of Matthew's Monocraterion, and M. Hébert (New Brunswick Museum) for assistance organizing, repairing, and cataloguing MISS samples collected for this study. We thank Margaret Horne for her assistance in the field and for transporting specimens and thin sections. We thank Randolph Corney in the Geology Department of Saint Mary's University for preparation of the thin sections. Specimens were collected under a Heritage Conservation Act Research Permit to R. F. Miller. We thank Dr. Martin Gibling, Dr. Spencer Lucas, and Dr. Nicolas Minter for useful discussions throughout the preparation of this manuscript. The feedback of two anonymous reviewers and the journal editors is also appreciated. The authors take sole responsibility for the content of the article.