‘Another piece of the puzzle’: Antarctica’s first-ever amber fossil sheds light on dinosaur-era rainforest that covered the South Pole 90 million years ago

For the first time, researchers have discovered a piece of fossilized resin, or amber, in Antarctica. The tiny golden fragment, discovered beneath the seafloor, contains microscopic remains of an ancient dinosaur-era rainforest that spanned the continent 90 million years ago, a new study reveals.

Amber is a fossilized resin, or tree sap, that can trap plants, insects, small animals, or other organic matter as it hardens. The golden yellow case is airtight and mostly transparent, meaning it perfectly preserves and displays everything inside, like a transparent time capsule.

Until now, amber fossils had been discovered on every continent on Earth except Antarctica. But in the new study, published Tuesday November 12 in the journal Antarctic ScienceResearchers identified a tiny piece of amber, about 0.002 inches (70 micrometers) in diameter, in sediment cores collected from beneath the seafloor at a depth of about 3,100 feet (950 meters) off the glacier Pine Island, on the west coast of Antarctica.

The tiny fragment dates back about 90 million years, during the Cretaceous Period (145 million to 66 million years ago). At that time, large parts of Antarctica were covered by temperate rainforest, similar to those found in New Zealand today, which thrived in warmer climatic conditions – and a tiny part of this Lost ecosystem is trapped in amber.

“This discovery allows a journey into the past in another, more direct way,” lead author of the study Johann Klagessedimentologist at the Alfred Wegener Institute in Germany, said in a statement. “Our goal now is to learn more about the forest ecosystem.”

Related: Wildfires burned Antarctica 75 million years ago, reveal charcoal remains

During the Cretaceous, large parts of Antarctica were covered by subtropical rainforest. (Image credit: J. McKay/Alfred-Wegener-Institut)

The sediment cores used in the study were first collected in 2017 and were later revealed to contain root fossils, pollen, spores and other remains of flowering plantswhich represent some of the best evidence of Cretaceous Antarctic rainforest.

The amber fragment was only recently discovered, as researchers split the remaining materials into thousands of small pieces and carefully analyzed each one using fluorescence microscopy. Further analysis revealed that it contained “micro-inclusions” from the bark that would likely once have lined a conifer-like tree that lived in the ancient forest.

The bark also shows signs of “pathological resin flow” – a strategy used by trees to seal damage to their woody protection caused by pests or wildfires, by creating a chemical and physical barrier with resin .

Microscope images of the amber show tiny pieces of bark buried in the fossilized resin. (Image credit: Johann P. Klages)

Although the new fragment is small, it is exceptionally well preserved despite being buried beneath the seafloor.

“Given its solid, transparent and translucent particles, amber is of high quality,” co-author of the study Henny Gerschela consultant from the Saxon State Office for Environment, Agriculture and Geology in Dresden, Germany, said in the release. The fragment must have spent most of the last 90 million years near the seafloor surface, “because the amber would (normally) dissipate under increasing thermal stress and burial depth,” he said. she added.

Researchers believe their findings could open the door to discovering more Antarctic amber, which could reveal even more secrets about this ancient rainforest and the dinosaurs that lived there.

“Our discovery is another piece of the puzzle,” Gerschel said.