Defining the “poorly defined” in ichnology: Biodeformational structures, bioturbation fabrics, and cryptobioturbation

Abstract

Indistinct, “poorly defined” bioturbation structures have been traditionally neglected in ichnologic analysis, mainly because ichnologists tend to focus on discrete trace fossils that provide high-resolution paleobiologic, paleoecologic, and sedimentologic information. In the seventies, when a seminal review of ichnologic nomenclature was proposed, concepts pertaining to this type of bioturbation were not fully developed, resulting in growing semantic instability and broadening over the years. We applied etymologic and semantic analyses to key terms, such as “biodeformational structure”, “bioturbation fabric” (=bioturbated texture), and “cryptobioturbation”, propose revised definitions and clarifications, and reassess related nomenclature (e.g. mantle and swirl structures, meioturbation, micro-, meio-, and macrobioturbation, Navichnia, Turbidichnia). Early definitions inadequately distinguished between bioturbation structures and fabrics, triggering a debate over the use of ichnofabric/bioturbated texture in the nineties. We emphasize that these concepts refer to two scales of analysis—the local scale, encompassing individual bioturbation structures, and the larger scale, representing the whole fabric produced by bioturbation. The terms “biodeformational structures” (indistinct bioturbation structures) and “bioturbation fabric” (fabric produced by bioturbation) should be retained. For the sake of terminological clarity, we suggest to abandon bioturbated texture, as it is synonymous with bioturbation fabric. With respect to cryptobioturbation, the emphasis on the process rather than the product has led to semantic instability, resulting in a myriad of studies invoking cryptobioturbation in disparate contexts. We recommend retaining the concept of cryptobioturbation fabric (i.e. a product), and replace the process of cryptobioturbation with diffusive bioturbation, defined here as bioturbation by biodiffusors and gallery biodiffusors promoting small-scale and relatively random particle transport, usually produced by meiofauna and small macrofauna. Advective bioturbation is its opposite term, mainly generated by upward and downward conveyors and regenerators. Finally, we characterize other common indistinct bioturbation fabrics (massive, banded, and mottled). Given the inherent genetic uncertainty of the rock record, we advocate that future ichnologic analyses be grounded primarily in fabric description (observation), while supporting the interpretation of fabric-forming processes, ethology, and taphonomy on this solid observational basis.

Publisher

Elsevier

Publication Date

9-2026

Publication Title

Earth-Science Reviews

Department

Geology

Document Type

Article

DOI

https://doi.org/10.1016/j.earscirev.2026.105565

Notes

Department: Geosciences

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