The fossils date back 55 to 40 million years ago, during the Eocene epoch. At that time, the world was much warmer and wetter, and these hothouse conditions meant there were palms at the North and South Pole and predominantly arid landmasses like Australia were lush and green. Reichgelt and co-authors looked for evidence of differences in precipitation and plant productivity between then and now.
Since different plants thrive under specific conditions, plant fossils can indicate what kinds of environments those plants lived in.
By focusing on the morphology and taxonomic features of 12 different floras, the researchers developed a more detailed view of what the climate and productivity was like in the ancient hothouse world of the Eocene epoch.
Reichgelt explains the morphological method relies on the fact that the leaves of angiosperms — flowering plants — in general have a strategy for responding to climate.








