For the first time, amber fragments have been recovered from Antarctica, or, to be more specific, from an offshore sedimentary basin. The fossils mean we now have amber samples from every continent, and provide information about Antarctica’s forests, which were once home to hardy dinosaurs.
Atmospheric carbon dioxide was high in the Cretaceous, making the world in general a warmer place. Moreover, the lack of an Antarctic Circumpolar Current meant the climatic difference was much greater on the southern continent, such that great forests grew there, inhabited by both dinosaurs and mammals.
There are, however, great gaps in our knowledge of the nature of these forests and their inhabitants, because it is so hard to access any fossil beds that preserve them. One way around this is to drill the sea floor off the Antarctic Coast, and a team led by Dr Johann Klages of the Alfred Wegener Institute hit paydirt off Pine Island in the Amundsen Sea.
Within a 5-centimeter (2-inch) thick layer of lignite (moist coal) the team found pieces of hardened tree resin, better known as amber. Based on the age and composition of the lignite the amber is estimated to be between 92 and 83 million years old, and came from a swampy forest mostly composed of conifers.
The resin is released by many tree species when their bark is damaged. Many resins, particularly those from conifers, fossilize under the right conditions, preserving insects, feathers, and a dinosaur tail. We already have amber fossils from the same era from southern Australia, which was still attached to Antarctica at the time, so it is no surprise specimens like this were preserved; finding them is a different matter. Located at almost 74 degrees south (and 107 West), the find is easily the most southern amber ever collected.
“The analyzed amber fragments allow direct insights into environmental conditions that prevailed in West Antarctica 90 million years ago,” said Klages in a statement. “Our goal now is to learn more about the forest ecosystem – if it burned down, if we can find traces of life included in the amber. This discovery allows a journey to the past in yet another more direct way.”
Unfortunately, the team ground up the lignite for analysis, and the pieces of amber that have survived are tiny, just 0.5-1.0 millimeters (0.02-0.04 inches) across, so the prospects of finding any well-preserved lifeforms inside are slim. However, signs of what may be tiny fragments of tree bark have been detected in the numerous fragments.
Fragments of what is thought to be tree bark trapped in one of the pieces of amber.
Image Credit: Johann P. Klages
In a paper reporting the discovery, the authors suggest the resin may have been a response to a forest fire, and was preserved when water covered the site and protected it from UV light. The fact the amber has survived and remained clear and translucent indicates it was never buried at great depth where it would be heated until it partially melted.
The location of the find led the authors to create a new category, Pine Island amber, into which the discovery was placed. The name may be coincidental, but given the forests from which the amber comes, it’s also appropriate.
The announcement is open access in Antarctic Science.
Source Link: First-Ever Antarctic Amber Spills Secrets Of The Continent's Cretaceous Forests
