253-2 Insights into the taphonomy, paleobiology and taxonomy of Amorphognathus and Eocarniodus from Late Ordovician conodont bedding plane associations

Session: Conodonts from North America and Beyond - Honoring the Career of Dr. James E. Barrick

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Abstract:

Conodonts preserved on bedding surfaces offer taphonomic, paleobiological, and taxonomic insights that are often inaccessible from isolated elements extracted via standard digestion techniques used in biostratigraphy. In Amorphognathus, individual S elements on bedding planes could extend nearly a centimeter in length and reveal that the posterior ramiform processes were flexible.  Disarticulation of these long processes occurs through two primary mechanisms. First, simple breakage due to compaction affects all elements. Second, in Amorphognathus S elements, disarticulation also resulted from rotation and slight dislocation of process subsections. This suggests that the long processes were not rigid structures but were composed of individual components connected by nonmineralized or weakly mineralized tissue.  Consequently, when recovered through digestion techniques, these components appear as small, isolated, unbroken elements. Rather than being fragments of a fully mineralized process, they likely functioned flexible chain of ramiform processes subsections within the conodont apparatus. These components, often misidentified as belonging to the genus Eocarniodus, consistently co-occur with Amorphognathus and are best interpreted as distal ramiform process components of that genus.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-5312

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