Samples of early Tertiary age fossil wood and leaves were collected from Seymour Island, Antarctic Peninsula, in 2001. Fossils from Palaeogene strata were studied to determine the nature of vegetation response to the fundamental change from greenhouse to icehouse climates in Antarctica. Palaeoclimate data was derived using CLAMP (Climate Leaf Analysis Multivariate Program) and several Leaf Margin Analysis (LMA) techniques based on the physiognomic properties of the leaves. Climate interpretation of the fossils produced new data on terrestrial climate change at high latitudes and were used to test and validate climate models, and to establish whether climate-induced changes in biodiversity occurred in a gradual or punctuated manner.