This dataset contains fossil occurrence data from the Cretaceous Lopez de Bertodano Formation (Maastrichtian), on Seymour Island, compiled in August 2022. Fossils were collected by Carlos Macellari and William Zinsmeister over several field seasons in the 1980s, and are presently (since 2010) reposited in the Paleontological Research Institution, Ithaca, NY. Data in this spreadsheet are presented by locality (station number, as compiled by PRI), with fossils identified at the family level. This work has been supported by Natural Environment Research Council (NERC) Independent Research Fellowship NE/S014756/1, awarded to EM. TMK is funded by a Cambridge International and Newnham College Scholarship, administered by Cambridge Trust. The Newnham College United States Travel Bursary funded TMK's visit to the PRI Collections. RJW and HJG are funded by UK Research and Innovation (UKRI) Future Leaders Fellowship MR/W01002X/1 "The past, present and future of unique cold-water benthic (seafloor) ecosystems in the Southern Ocean" awarded to RJW. HJG is also funded by BIOPOLE, under the National Capability Science Multi-Centre award scheme (NC-SM2).

During field work in 2001 over 1600 specimens were collected from four main fossil plant assemblages: the 'Nordenksjold flora' from the Cross Valley Formation of Late Palaeocene age; and 3 floras from La Meseta Formation i) Flora2 from the Valle De Las Focas allomember, ~late Early Eocene, ii) Wiman Flora, Acantilados allomember, late Early/mid Eocene, iii) Cucullaea 1, Cuculleae 1 allomember Flora, early Late Eocene. In addition smaller collections of fossils from other parts of the La Meseta Formation were collected. The work concentrated on the Late Palaeocene and the Cuculleae 1 floras as these were the best preserved and had sufficient morphotypes for climate analysis. In the Late Palaeocene flora 36 angiosperm leaf morphotypes were identified, along with 2 pteridophytes (ferns), and podocarp and araucarian conifers. Discovery of several new leaf types indicates that the Tertiary floras from Antarctica were more diverse than previously thought.

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.