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Title: One fossil record, multiple time resolutions: disparate time-averaging of echinoids and mollusks on a Holocene carbonate platform
Authors: Kowalewski, M
Casebolt, S
Hua, Q
Whitacre, KE
Kaufman, DS
Kosnik, MA
Keywords: Statistical data
Quaternary period
Cenozoic era
Carbon 14
Bahama Islands
West Indies
Caribbean Sea
Issue Date: 11-Nov-2017
Publisher: Geological Society of America
Citation: Kowalewski, M., Casebolt, S., Hua, Q., Whitacre, K. E., Kaufman, D. S., & Kosnik, M. A. (2018). One fossil record, multiple time resolutions: disparate time-averaging of echinoids and mollusks on a Holocene carbonate platform. Geology, 46(1), 51-54. doi:10.1130/G39789.1
Abstract: Our quantitative understanding of the temporal resolution of the fossil record is largely based on numerical dating of Holocene bivalves. However, for paleontologically important taxa with less-robust skeletons, no quantitative estimate of time-averaging exists. Here, we compare time-averaging in sympatric accumulations of the echinoid Leodia sexiesperforata and the bivalve Tucetona pectinata on a shallow carbonate platform of San Salvador Island, Bahamas. Using graphite-target and carbonate-target accelerator mass spectrometry (AMS) radiocarbon methods, we dated 30 echinoid tests and 30 mollusk valves collected from surficial sediments at a single site. All echinoid tests yielded post-bomb (taking into account radiocarbon from nuclear weapons testing) ages, and the estimated time-averaging (interquartile age range) is at most 2 yr. In contrast, sympatric mollusk valves spanned 4000 yr with an estimated time-averaging of 1830 yr. This three-orders-of-magnitude difference in the extent of time-averaging quantifies the taphonomic expectation that echinoid tests should degrade more rapidly and experience less time-averaging when compared to more durable mollusk shells. When preserved, fossil echinoids are likely to indicate a more finely resolved fossil record than skeletally robust organisms such as mollusks, and may provide a fundamentally distinct class of paleontological data, potentially adequate for investigating biological and physical processes that operate at subdecadal time scales. Immensely disparate time-averaging of sympatric mollusks and echinoids indicates that, at broader phylogenetic scales, differences in intrinsic skeletal durability may be the main determinant of the temporal resolution of fossil assemblages. Copyright © 2017 Geological Society of America
ISSN: 1943-2682
Appears in Collections:Journal Articles

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