34 Paleontology

Wednesday, 11 March 2026
8:30 AM - 10:00 AM
RCC, 103

Reassessing the Taphonomic Clock: Skeletal Alteration in Radiocarbon-Dated Marine Invertebrates

Paper number: 34-3
Program: Technical Sessions
Time: 9:15 AM – 9:30 AM

Authors

Abstract

Skeletal invertebrate remains accumulating on modern seafloors often form time-averaged assemblages providing an opportunity to directly evaluate the hypothesis of the taphonomic clock. The hypothesis is that taphonomic alterations of specimens should increase as a function of time, with newly dead specimens being less damaged than specimens that died long time ago. To test this, we analyzed the age-alteration relationships of 635 radiocarbon-dated specimens, which included complete and fragmentary skeletal remains of irregular echinoid and mollusks. All specimens came from shallow, mixed siliciclastic-carbonate marine environments in Carrabelle and Cedar Key, Florida. Specimen age-size and alteration-size relationships were also evaluated.

Each specimen was scored for presence (score of 1) or absence (score of 0) of taphonomic alterations, including fragmentation, encrustation, bioerosion, abrasion, staining, luster loss (mollusks only), center breakage (echinoids only), and spine presence (echinoids only). The scores were then combined into a Total Taphonomic Score (TTS). Specimen size was quantified using mass measurements (grams). Relationships among age, size, and taphonomic alteration were evaluated using Spearman rank correlations.

The results indicate that TTS and radiocarbon age show moderate, statistically significant rank correlation for complete echinoid specimens (ρ = 0.297, p =0.006), but not echinoid fragments (ρ = -0.137, p = 0.06). Conversely, the degree of alteration appears related to specimen mass for fragments (ρ = 0.281, p < 0.0001), but not complete specimens (ρ = -0.143, p = 0.196).

The results for mollusks indicate a moderate and significant TTS-age correlation (ρ = 0.209, p = 0.005). However, a moderate but significant correlation is also observed for mollusk fragments (ρ = 0.162, p = 0.037). A weak statistically significant TTS-mass correlation was observed for complete mollusk specimens (ρ = 0.169, p = 0.025), but not for fragments (ρ = -0.121, p = 0.12). Finally, the correlation between specimen radiocarbon age and specimen mass is insignificant for both complete and fragmentary echinoids and mollusks (ρ < 0.06, p > 0.39 in all cases).

Our results are consistent with previous studies, which indicated that there is a weak statistical tendency for older specimens to be more altered. They also indicate that the age-size-taphonomy relationship does not vary dramatically across taxa. Recent studies suggest that the assemblage-level taphonomic signatures may be a good predictor of time averaging, despite the fact that the taphonomic clock appears unreliable for assessing the post-mortem history of individual specimens.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411881

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