217-2 Exploring the Taphonomic Clock: Skeletal Alteration in Radiocarbon-Dated Specimens of Echinoids and Mollusks

Session: Paleontology, Paleoecology/Taphonomy

Presenting Author:

Authors:

Abstract:

Enrique Hernandez

8/4/25

Exploring the Taphonomic Clock: Skeletal Alteration in Radiocarbon-Dated Specimens of Echinoids and Mollusks

HERNANDEZ, Enrique¹, TORRES Jr., Luis^1,2 and KOWALEWSKI, Michal², (1)Department of Geological Sciences, University of Florida, 1843 Stadium Rd, Gainesville, FL 32603; Division of Invertebrate Paleontology, Florida Museum of Natural History, 1659 Museum Rd, Gainesville, FL 32611, (2)Division of Invertebrate Paleontology, Florida Museum of Natural History, 1659 Museum Rd, Gainesville, FL 32611; Department of Geological Sciences, University of Florida, 1843 Stadium Rd, Gainesville, FL 32603

Skeletal remains of biomineralizing invertebrates that accumulate on modern seafloors may form time-averaged fossil assemblages with various levels of post-mortem taphonomic alteration. It is generally expected that recently deceased specimens are less likely to be taphonomically altered than older ones. We analyzed a large dataset of radiocarbon-dated specimens of echinoids and mollusks (n = 397) sourced from present-day shallow marine environments in the northern Gulf of Mexico (Carrabelle and Cedar Key, Florida) to test two hypotheses: 1.)  Older specimens will display higher taphonomic alteration and 2.) Specimen mass will correlate with their radiocarbon age.

Each specimen was scored for their taphonomic alteration using standardized attributes such as fragmentation, encrustation, bioerosion, luster loss (mollusks only), staining, abrasion, center breakage, and spine presence (echinoids only). The standardized combination of these individual taphonomic scores is used to quantify the overall level of taphonomic alteration: the Total Taphonomic Score [TTS].

For both studied taxa, Spearman correlations revealed a significant relationship between the radiocarbon age and TTS (Mollusks: ρ = 0.39, p = 2.11×10⁻⁹; Echinoids: ρ = 0.30, p = 5.65×10^-5). However, only echinoids were found to possess a significant relationship between radiocarbon age and mass (Mollusks: ρ = –0.04, p = 0.57; Echinoid: ρ = 0.56, p = 9.57 x 10^-16). The results suggest that older specimens (<1000 years) exhibit greater taphonomic alteration for both taxa. Consequently, the dominance of unaltered specimens in fossil assemblages may indicate less substantial time averaging. The correlation between echinoid specimen mass (body size) and radiocarbon age suggests that larger specimens are surviving for longer periods of time than smaller specimens, possibly due to higher resistance of larger specimens to mechanical breakage and dissolution. These results suggest that echinoids and mollusks differ in their size-related taphonomic filters.  

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

doi: 10.1130/abs/2025AM-11098

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