Australasian Science: Australia's authority on science since 1938

Lilly Pilly Fossils Reveal Snowless Snowy Mountains

Leaf fossils of the iconic Australian tree, the lilly pilly, have been discovered high in the Snowy Mountains, revealing a past history of warmer rainforest vegetation and a lack of snow.

Lilly pilly trees (Syzygium) occur naturally in tropical to subtropical rainforests throughout Australasia, southern Asia and Africa – not mountain slopes covered by winter snow. They are commonly planted in streets and gardens across Australia, where they are prized for their glossy green leaves, white flowers, and red or pink edible fruits.

Researchers from the University of Adelaide recovered fossilised lilly pilly leaves from old gold mining pits near the historic town of Kiandra, 1400 metres above sea level in the Snowy Mountains of New South Wales. The fossils were preserved in ancient lake sediments, overlain by basalt rock, deposited by lava flows that erupted during some of the last stages of uplift that produced the Eastern Highlands about 20 million years ago.

“The lilly pilly was a traditional food source for Aboriginal peoples and early European settlers, and is still an important food source for many native animals and birds, as well as used for making cakes and jams,” says lead researcher Mr Myall Tarran, a PhD candidate in the University’s School of Biological Sciences. “But despite being such an important and iconic plant, no convincing fossils have ever been described in the scientific literature – until now.

“These fossils add to growing evidence that in this region about 20 million years ago there would have been temperate rainforest. The climate was warmer and wetter, perhaps analogous to the modern-day Atherton Tablelands in North Queensland. There would have been no, or very little, winter snowfall, and the alpine zone, as we know it in the Snowy Mountains, was not yet established.”

Tarran says it’s possible the lack of snow was a result of continuing tectonic uplift, but higher atmospheric carbon dioxide levels were likely to have played a role. “Uplift still hadn’t fully finished in the region at that stage, so perhaps this forest was actually growing at a slightly lower altitude,” he says. “But we also know that atmospheric carbon dioxide levels, and therefore global average temperatures, were much higher during this time.”

The research was published in the American Journal of Botany (https://goo.gl/YALZcF).