Paper No. 161-1
Presentation Time: 9:00 AM-6:30 PM
3D IMAGING OF FORAMINIFERA: ANALYSIS OF GROWTH
BARNHILL, Kelsey Archer1, TOWBIN, Henry
2, HOPKINS, Melanie
3, THOMAS, Ellen
4, O'LEARY, Ruth
5, LANDMAN, Neil H.
6 and HUSSAINI, Bushra M.
3, (1)Paleontology, South Dakota School of Mines and Technology, 501 E. Saint Joseph St., Rapid City, SD 57701; Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, (2)Microscopy and Imaging, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, (3)Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, (4)Geology and Geophysics and Department of Earth and Environmental Sciences, Yale University and Wesleyan University, P O Box 208109, New Haven, CT 06520-8109, (5)Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, (6)Division of Paleontology, American Museum of Natural History, Central Park West at 79th St, New York, NY 10024, kelsey.barnhill@mines.sdsmt.edu
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.
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