T161 Microfossil Proxies in Earth History (Posters)

Monday, 26 September 2016
9:00 AM - 6:30 PM
Exhibit Hall E/F

3D IMAGING OF FORAMINIFERA:  ANALYSIS OF GROWTH

Paper number: T161-1
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

Foraminifera are important microfossils used in analysis of paleoclimates and paleoenvironments. Examining their ontogeny (including size of the protoconch) and growth rates can provide insight into their ecology and life history, e.g., food supply in the environments where they lived. In planktic taxa, shifts in habitat (e.g., moving to deeper water near gametogenesis) may be reflected in growth patterns.

Computed Tomography (CT) imaging of Foraminifera allows scientists to examine specimens in three dimensions (3D), without destruction of the specimen, and at a high resolution. We selected 5 specimens from over 80 CT scanned and 3D imaged Foraminifera in the AMNH microfossil collection (curation and CT imaging funded by NSF award #1203394). Surface area and volume of each individual chamber space and its enveloping test wall were measured in the benthic lagenid Vaginulinopsis baggi McLean 1955 (Miocene, Maryland, USA; Order Lagenida), the benthic biserial Hopkinsina magnifica Bramlette 1950 (Monterey Fmt, Miocene, California USA; Order Rotaliida), the two benthic rotaliid trochospiral species Anomalina mantaensis Galloway and Morrey, 1929 (Eocene, Ecuador; now commonly placed in the genus Riminopsis) and Valvulineria johnsoni Coryell and Mossman (1942, Pliocene, Panama), and the rotaliid planktic trochospiral Globorotalia truncatulinoides nana Bermudez 1960 (Gulf of Venezuela, Recent), in order to investigate the ontogeny (isometric/allometric growth patterns) and growth rates in different taxonomic groups of Foraminifera. After the protoconch, spiral and biserial taxa have generally logarithmic growth curves, with a change in shape in the planktic species, with highest growth rates in H. magnifica (from the highly eutrophic Monterey Fmt), and lowest in A. mantaensis.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-279950

© Copyright 2016 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.