The information presented here represents preliminary research as the result of ten-weeks of investigation in-residence at the National Museum of Natural History. This is not an official publication of the information.

As preliminary information, results and/or findings should not be cited as part of conclusive work. Please contact the authors first if you wish to utilize the information presented here.

Introduction

At least eight species of foraminifera, a group of marine protists that comprise an important part of the fossil record, in the genus Globigerinelloides (G. multispinus, G. prairiehillensis, G. messinae, G. subcarinatus, G. volutus, G. alvarezi, G. aspensis, and G. impensus) are frequently identified in various studies of Late Cretaceous marine sediments, but opinions vary as to which of these species names are accurate and should be retained. In an effort to stabilize the taxonomy of this group, primary type specimens of most of these species were compared with Globigerinelloides morphotypes from ODP Site 690 (Weddell Sea), Site 1049 (subtropical North Atlantic), DSDP Sites 463 and 465 (tropical Pacific), and DSDP Site 511 (Falkland Plateau).

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Materials and Methods

Ontogenetic morphometric data, coiling metrics, and shape analysis based on high-resolution x-ray images taken from umbilical and edge views were extremely useful in characterizing population variability for each of these planispirally coiled morphotypes. With logarithmic plots of cross-sectional chamber area increase from the proloculus (first chamber) to the ultimate chamber, the ontogenetic trajectories of distinct species and morphogroups can be used to aid in determining phylogenetic relationships (Fig. 1). The chamber area and diameter data sets were collected using ImagePro 4 biometric software; other metrics were acquired with programs written for the Smithsonian by Ralph Chapman.

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Results and Conclusions

Our results indicate that Late Cretaceous Globigerinelloides include two distinct lineages, one with 10 to 15 chambers and the other with 20 to 25 chambers in adult specimens.

We have identified a new species in this latter group that will be described at a later date.

Differences in chamber shape, chamber size increase rates, the number of chambers in the final or initial whorl, proloculus diameters, and external shell ornamentation are used to delineate species populations within these two lineage groups.

The question of synonymy remains uncertain due to the unavailability of several key type specimens; however, this study has determined that G. volutus is the senior synonym of G. messinae messinae.

Other such relationships will be elucidated in the near future thanks to the possible rediscovery of the holotype of G. alvarezi.

Our study has also extended the known biostratigraphic ranges for both G. alvarezi and G. prairiehillensis.

Stable isotope analyses of the biometrically differentiated Globigerinelloides taxa will be obtained to determine their relative depth ecologies.

Pre-Campanian Globigerinelloides taxa will be similarly analyzed to reconstruct their Late Cretaceous phylogenetic history.

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Acknowledgements

We would like to thank the National Science Foundation for their support of the Smithsonian Institution's Research Training Program, Ralph Chapman, MyLe Ducharme, RTP director Mary Sangrey, Nina Butler, the Smithsonian Women's Committee, Navarro Bharat, Diego Cisneros-Heredia, and the RTP intern class of 2002 for all of their assistance.

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ENTOMOLOGY

Sarah Garrett
"An Inventory of Leafroller Species of Moths of the Great Smoky Mountains National Park"

Abstract / Summary

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