Hobart, Tasmania — Newly uncovered remains of a 53-million-year-old polar forest near Macquarie Harbor in western Tasmania have revealed crucial insights into the ancestral origins of rainforest plants in the southern polar region. This groundbreaking discovery, made by Dr. Miriam Slodownik, a recent Ph.D. graduate from the University of Adelaide, offers a fresh understanding of the early evolution of southern rainforests during the early Eocene epoch, a period known for its extreme greenhouse conditions.
“This discovery offers rare insights into a time when global temperatures were much higher than today,” said Dr. Slodownik. “Tasmania was much closer to the South Pole, but the warm global climate allowed lush forests to thrive in these regions.”
The fossils, found near Strahan in Western Tasmania, include an array of plant life, with two newly identified conifer species: Podocarpus paralungatikensis and Araucaria timkarikensis. Additionally, the site revealed various fern and tree species, many of which are ancestors of the flora now found in Australia, New Zealand, Indonesia, and South America.
“The most spectacular fossils are relatives of the Kauri, Bunja, and Wollemi pines, which provide clues about the evolution of these iconic Australian trees,” noted Dr. Slodownik. Her research has been published in the American Journal of Botany.
Over 400 new fossils have been excavated and analyzed at the Paleobotany Laboratory of the University of Adelaide. Advanced techniques like ultraviolet photography and microscopic analyses have revealed intricate details of leaf and cellular structures, offering vital insights into the relationship between these ancient plants and their modern descendants.
In collaboration with the Tasmanian Aboriginal Center, the new fossil species were named in palawa kani, the Aboriginal language of Tasmania. The names recognize the original owners and long-time occupants of the land: Paralungatik is the original name of Macquarie Harbor, and Timkarik refers to the Strahan area.
“These fossils highlight the historical connections between Antarctica, South America, and Australia, which were once part of the ancient supercontinent Gondwana,” said Dr. Slodownik. “The analyses showed how these plants adapted and thrived across the Southern Hemisphere in warm, ice-free conditions, even with the extreme seasonal changes near the polar circle.”
As Earth’s climate cooled and glaciers covered the polar regions, the landmass that is now Australia drifted northward. This movement carried the polar plants toward the equator, where they evolved into the species that now populate Australia and neighboring regions.
“This study revealed the amazing diversity of Tasmania’s fossilized forest. These plants tell the story of big changes in climate and shifting tectonic plates over millions of years,” Dr. Slodownik explained. “Through this research, my team and I have continued the University of Adelaide’s tradition of leading paleobotanical research, contributing crucial insights into plant evolution and the dynamics of our planet in deep time.”