Funded through a Drinko Distinguished Research Fellowship grant from the Drinko Academy at Marshall, his research has focused on the plesiosaur, an ocean-dwelling lizard from the age of dinosaurs, and was conducted in partnership with South American scientists. They discovered whale-like feeding habits of the marine reptile through fossils that are approximately 65 million years old. Involved in the research were fossils from Antarctica found in the early 1980s that could never be interpreted. O'Keefe and his co-authors, including scientists from Chile and Argentina, used different fossils from Chile and Argentina to determine how the pieces from Antarctica went together and may have functioned. Their research has been published in the Journal of Vertebrate Paleontology. The title of their paper was, "Cranial Anatomy of Morturneria seymourensis from Antarctica, and the Evolution of Filter Feeding in Plesiosaurs of the Austral Late Cretaceous."