This dissertation is a widespread compilation of research covering vastly different times and locations. Despite these differences, the use of foraminifera helps to unravel their geologic history, revealing the paleoenvironmental, paleoclimatic, and paleoceanographic conditions of each location. What unites each study is how water mass, food supply and oxygen concentration play a critical role on the microfossil assemblage. This dissertation is broken up into three unique chapters. Chapter 1 reexamines some old ideas of how benthic foraminifera can be used as water mass indicators. A 13-myr record from Shatsky Rise in the paleo-central Pacific Ocean contains several instances water mass changes driven by tectonism, gateway changes and possible glaciation towards the end of the Late Cretaceous (78 –66 Ma). Each of these water mass shifts correlates with distinct foraminiferal changes. Chapter 2 expands on research in the Western Interior Seaway (WIS) during the Late Cretaceous. An ocean anoxic event (OAE) is well-preserved throughout the seaway during a time of sea level rise at the Cenomanian–Turonian (~94 Ma). Extensive studies on foraminifera in the southern part of the seaway document the biotic effects of OAE2, but little is known to the far north. Billings, MT was in a unique position where it shared properties of the northern WIS in Canada at certain times but at other times took on a southern WIS characteristic. This is attributed to an oceanographic front that moved through the seaway as sea level rose and fell. Chapter 3 is a Miocene–Recent (~23 Ma) evaluation of benthic foraminifera in one of the most southern-drilled sites of Antarctica in the Ross Sea. This study utilizes microfossils to understand the history of the Ross Ice Shelf during times of global warmth. Recent foraminifera provide information of how warm water masses near the grounding line create conditions unique to the eastern Ross Sea.