The Palaeocene fossils on Seymour are mostly plant fossils from a forest dominated by the Antarctic Beech. It still grows in Australia, New Zealand, South America and New Caledonia. 55 millions years ago when these trees were alive, the forest stretched from Brisbane to Buenos Aires in a continuous corridor.
By the Eocene Epoch, the island was back under the sea. The fossils found from this time are the oldest known whale and penguin remains. In fact Seymour Island has the fossils of numerous species of penguin dating from 45 million to 34 million years ago. The waters had warmed and changes in the fauna can be tracked over 8 million years. Fragile invertebrates flourished in the colder periods but as the temperature rose so did the hard-toothed fish and goodbye invertebrates.
The first of the Antarctic dinosaurs was found in the mid 1980s on James Ross Island. Then a variety of Cretaceous-aged plant-eating dinosaurs on James Ross and Vega Islands. In 2005, the remains of a meat-eating theropod dinosaur were recovered followed by fossil mammals and the world's oldest duck. In 1992 on Vega, a partial skeleton of a bird, approx 66-68 million years old, was found which belonged to the modern group of ducks, geese, and swans.
On the Antarctic continent itself, several dinosaur fossils have been recovered. These are major finds because of their age, the early Jurassic Period, around 190 million years ago. Fossil deposits of this age aren't easily found anywhere in the world. The latest find in the Trans Antarctic Mountains in 2005 was a large sauropod or long-necked dinosaur.