Honors Theses


Rachel Sales


Daniel Goldman



Publication Date

Spring 4-2015

Document Type

Honors Thesis


The purpose of this study is to examine the biodiversity patterns of a group of fossil organisms called chitinozoans. Chitinozoans are organic-walled, planktonic microfossils that first appear in the Early Ordovician Period (488 million years ago) and diversify rapidly through the Paleozoic Era. The Ordovician Period was a time of great global climate change, and by studying this group of fossil plankton, we hope to better understand how modern plankton, which are the base of the marine food chain, might respond to climate change. We used a method called constrained optimization (CONOP9) to construct a composite range chart of 152 chitinozoan species from 65 Ordovician drill cores and outcrops from the paleocontinent Gondwana. Our results show that chitinozoan biodiversity increases throughout the Early and Middle Ordovician, peaks in the middle part of the Late Ordovician and declines thereafter. These results differ from biodiversity estimates derived from more traditional species counting methods.

Permission Statement

This item is protected by copyright law (Title 17, U.S. Code) and may only be used for noncommercial, educational, and scholarly purposes.


Earth Sciences | Geology | Physical Sciences and Mathematics

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