Fossilized penguin bones found in Antarctica reveal that the icy continent at the southern end of the planet was, in the past, a warm and humid environment.
The discovery, published in the journal ‘Fossil Record‘, was made by paleontologists at the China University of Geosciences, through the analysis of fossils collected on Seymour Island, in the Weddell Sea, off the coast of the Antarctic Peninsula.
Using non-destructive X-ray mapping techniques to examine the composition of the fossilized remains, the team says this work shows that ancient bird bones can function as to act as “chemical archives” of past climate conditions.
“Penguins are among the most iconic animals of Antarctica and represent one of the most notable groups of birds, having completely lost the ability to fly and, instead, using their wing-flippers to swim,” say the researchers.
“Seymour Island preserves one of the richest and most stratigraphically continuous records of Eocene penguin fossils anywhere in the world. These fossils span an important period in the climatic evolution of Antarctica, from relatively warm and humid conditions in the early Eocene to a cooler climate in mid- to late-Eocene,” they explain.
The analysis of the bones revealed clear differences in chemical composition associated with different geological periods. In other words, each set of bones preserved in its composition a “chemical imprint” of the climatic conditions at the time when the penguin likely died.
Older fossils, up to 55 million years old, contained higher levels of titanium, silicon and potassium, and scientists associate these elements with a warmer and wetter climate, in which much more water flowed across the land, dissolving the rocks of the environment and eventually transporting and “trapping” these elements in the fossils.
On the other hand, more recent fossils showed much lower levels of these elements.
Furthermore, the researchers reveal having detected iron, manganese and sulfur within the bones themselves, which they say reflect chemical changes in the marine sediments as, over time, the penguin remains became increasingly buried.
At a time when many in the global scientific community are seeking to reconstruct past climates to understand what is happening in the present and what may happen in the future, this team believes that “fossils can be an important supplementary source of information for the study of paleoenvironmental changes on the Antarctic Peninsula”.
