253 Conodonts from North America and Beyond - Honoring the Career of Dr. James E. Barrick
Talks concerning recent developments in the study of conodonts in North America and beyond. The session is held by the Pander Society in honor of the contributions of Dr. James E. Barrick, Texas Tech University.
Wednesday, 22 October 2025
8:00 AM - 12:00 PM
HBGCC, 304A
Malformed Polygnathid Conodonts Across the Kinderhookian-Osagean Boundary (Mississippian)
Paper number: 253-6
Program: Technical Sessions
Time: 9:20 AM – 9:35 AM
Authors
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James DayIllinois State UnivDept Geography & Ge, Normal, IL
Abstract
A literature search reveals numerous examples of malformed, likely pathological, polygnathid conodonts from the late Kinderhookian/early Osagean. The most obvious style of malformation is a bifurcation of the dorsal tip of the platform, usually with the development of a secondary keel on the aboral side of the element. Polygnathus specimens with this condition are common enough that a subspecies name (Polygnathus communis bifurcatus Hass 1959) was erected and used by multiple other authors. It can now be considered a "nomen mutans". Many of the malformed polygnathids likely achieved maturity (based on sizes comparable to normal specimens from the same faunas) because the dorsal tips of the platform are not involved in occlusion and therefore did not need to mirror the opposing element for functionality. The inferred increased abundance of malformations during the Kinderhookian-Osagean boundary interval may reflect rising environmental stress (e.g., fluctuating asymmetry) during the coeval major positive carbon isotope excursion (KOBE/TICE).
Geological Society of America Abstracts with Programs. Vol. 57, No. 6
doi: 10.1130/abs/2025AM-414931
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