The fossils of the giant rainforest tree Dryobalanops rappa found in Brunei (officially Brunei Darussalam), a country on the large island of Borneo, are the first fossil evidence of a living endangered tropical tree species. The discovery highlights new potential for fossils to inform heritage values and paleoconservation in Southeast Asia.
Leaf architecture of fossil (A, B, E) and comparable living (C, D, F-H) Dryobalanops species. Image credit: Wang et al., doi: 10.1002/ajb2.70036.
Known locally as the kapur paya, Dryobalanops rappa is a towering dipterocarp tree that still exists today but is endangered and found in the carbon-rich peatlands of Borneo, including Brunei.
The 2-million-year-old fossil leaves of this species were found at Kampong Lugu in Tutong district of Brunei.
“This discovery provides a rare window into the ancient history of Asia’s wet tropical forests,” said Tengxiang Wang, a doctoral student at Penn State.
“We now have fossil proof that this magnificent tree species has been a dominant part of Borneo’s forests for millions of years, emphasizing its ecological importance and the need to protect its remaining habitats.”
“Until now, the fossil record of Asia’s wet tropical forests has been surprisingly scarce compared to the Amazon and Africa,” said Penn State’s Professor Peter Wilf.
The paleontologists identified the fossils by analyzing microscopic features of the preserved leaf cuticles, which revealed a perfect match with modern Dryobalanops rappa, down to the last cellular detail.
“Our findings highlight that these forests are not just rich in biodiversity today but have been home to iconic tree species for millions of years,” Wang said.
“Conserving them is not only about protecting present-day species but also about preserving a legacy of ecological resilience that has withstood millions of years.”
“Dipterocarps, the dominant tree family in Asia’s rainforests, are critical for carbon storage and biodiversity,” the researchers said.
“However, they are increasingly threatened by deforestation and habitat destruction.”
“By revealing the deep historical roots of these trees, this discovery adds an important new perspective to conservation efforts.”
“The findings add a new dimension to conservation; we are not only protecting modern species but ancient survivors that have been key components of their unique ecosystems for millions of years,” Wang said.
“This historical perspective makes both the endangered trees and their habitats even more valuable for conservation.”
“Our study also shows how fossil evidence can strengthen conservation strategies for threatened species and ecosystems based on their historical significance.”
“Understanding the history of tropical forests is essential for their conservation, especially as many key species face rapid decline,” Professor Wilf said.
“Our finding fossils of living, endangered, giant tree species provides a vital historical foundation for conserving tropical Asia’s keystone trees, the rapidly disappearing dipterocarps.”
The discovery is reported in a paper in the American Journal of Botany.
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Teng-Xiang Wang et al. Fossils of an endangered, endemic, giant dipterocarp species open a historical portal into Borneo’s vanishing rainforests. American Journal of Botany, published online May 8, 2025; doi: 10.1002/ajb2.70036
