Professor Jane Francis from Leeds University gave a talk at the SCAR 2012 Open Science Conference on sea ice during the Cretaceous period.
During the Cretaceous (approximately 70 million years ago), the Antarctic continent was much warmer than today, with forests on Seymour Island. Dinosaurs stalked the land and huge sharks lived in the ocean. The ammonites and marine fossils that are now abundant on James Ross Island were swimming around. However, large sea level jumps of up to 25 m have been observed in New Jersey, suggesting that at this time, small ice caps were in existence, causing eustatic sea level fall. However, the evidence for glaciers and ice caps in polar regions is sparse.
Professor Francis demonstrated that the extensive sedimentary outcrops on Seymour Island held many well-preserved marine microfossils, but that there was no clear, comprehensive evidence for climate change. However, she presented evidence of new marine dinoflagellate cysts that could have lived in sea ice, suggesting periodic colder periods. Small glaciers and ice caps may have persisted on the Antarctic Peninsula mountains during this time.