Developing methods to determine the timing of oil exposure of protected species, such as bottlenose dolphins (Tursiops sp.), prior to death would be an important tool for natural resource damage assessment investigators. Teeth contain a permanent record of trace element accumulation throughout an animal's lifetime. This uptake can be influenced through diet and atmospheric inhalation. A SEM-EDS has a solid-state EDS detector which has increased sensitivity compared to older instruments that can detect trace amounts of geochemical elements. Our results suggest that this SEM-EDS can detect oil signatures in the dolphin growth layers (GLGs) of teeth. If dolphins are exposed to oil just prior to death, nickel (Ni) and vanadium (V), two common elements in crude oil, should appear in higher concentrations in the GLG closest to the pulp cavity of the tooth where the most recent GLG was deposited. Trace element concentrations in teeth from bottlenose dolphins that stranded alon the northern Gulf of America (GOA) coastline pre-, durng, and post- Deepwater Horizon (DWH) years (2010-2013) were compared to bottlenose dolphins that stranded during the same time periods in two areas suspected to have not been impacted by the oil spill (Sarasota, Fl in the GOA and South Carolina in the Atlantic Ocean). Results showed detection of Ni and V almost exclusively in teeth of dolphins that stranded in the norther GOA during the DWH oil spill period. All exposed dolphins were from the Grand Isle/Barataria Bay region of Louisiana, an area that was heavily oiled and negatively affected local bottlenose dolphins. 60% of samples analyzed from the impacted animals contained detectable levels of Ni and V. Nickel and V signatures were not detected in any dolphin tooth samples pre DWH or during DWH in Sarasota dolphins, but Ni and V was detected in two dolphins from Sarasota post DWH. Nickel and V signatures were not detected in any tooth samples from dolphins stranded in South Carolina. These results could assist natural resource managers in assessing dolphin exposure to oil spills both spatially and temporally, as well as for other odontocete species that reside in the northern GOA (e.g., sperm whale, Physeter macrocephalus) which culd have been negatively impacted by the DWH oil spill and future spills.