A tiny fragment of Earth's crust that broke from northwestern Australia around 150 million years ago transported hundreds of flowering plant species north across the prehistoric Tethys Ocean, ultimately seeding the tropical rainforests of Southeast Asia, a new study reports. The findings challenge earlier theories that the region's flora evolved after the dinosaur extinction.
The fragment, known as the West Burma Block (WBB) or Burma terrane, spent tens of millions of years near the equator as it drifted north, providing a refuge where ancient plant lineages could survive and diversify, the researchers said. It collided with Southeast Asia starting about 50 million years ago, after the Indian Plate bumped into it and altered its orientation around 80 million years ago.
For the study, researchers examined more than 3,000 plant fossils from Myanmar that were preserved in amber around 100 million years ago. The fossils included flowers, leaves, fruits and seeds belonging to at least 392 types of flowering plants and a vast array of conifers, ferns, mosses, cycads and liverworts.
"The rich tropical rainforest flora of [Southeast Asia] is not endemic but owes much of its biota to the great southern land, Gondwana," study co-author Byron Lamont, a distinguished professor emeritus at Curtin University, told Live Science in an email.
The WBB did not strip Australia of its ancient flora, because descendants of many plants found in the amber still exist in the country's hot and humid Northeast, Lamont said. It is hard to say what kinds of animals arrived in Southeast Asia via the WBB, because only creatures small enough to be preserved in amber are represented in this fossil assemblage. The animals present include small insects such as ants and mosquitoes; typical Australian vertebrates arrived in Australia much later, after the WBB had split off.
Amber has been mined from the north end of the WBB valley for at least a century. "Its beautiful fossils, preserved in 3D, have long attracted interest for their novelty value alone and there has been much commercial interest in them, especially from Chinese traders," Lamont noted.
The findings were published Oct. 27 in the journal Nature Ecology & Evolution.
Analysis
Why This Matters
- The study rewrites the evolutionary history of one of the world's most biodiverse regions, showing its deep Gondwanan roots rather than a post-dinosaur origin.
- It demonstrates how ancient plate tectonics can shape modern ecosystems, carrying entire floras across oceans.
- Understanding these deep origins may inform conservation strategies for Southeast Asian rainforests under threat today.
Background
The West Burma Block originated from the supercontinent Gondwana, which included Australia, Antarctica and India. It drifted north for about 100 million years, isolated near the equator, before colliding with Southeast Asia. The study used amber fossils from Myanmar to trace the plant lineages, providing a 3D snapshot of life from the mid-Cretaceous period.
What to Watch
- Further fossil discoveries in Myanmar, especially of vertebrates, could reveal what animals accompanied the plant migration, though larger ones are rarely preserved in amber.
- Ongoing political and commercial pressures in Myanmar may affect access to amber deposits and future research.
- Comparative studies with other Gondwanan fragments, such as India, could test whether similar seeding events contributed to tropical floras elsewhere.
Checked
12 claims in this story checked against 1 source: 11 supported.
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- SupportedA tiny Australian fragment seeded Southeast Asia’s tropical forests, according to the study.Latest from Live Science: “Southeast Asia's tropical forests owe their rich biodiversity to a tiny fragment of Earth's crust that split from what is now northwestern Australia roughly 150 million years ago, a new study reports.”
- SupportedAmber fossils reveal that a drifting microplate carried hundreds of plant species north from Gondwana toward Southeast Asia.Latest from Live Science: “The fragment transported hundreds of flowering species and a flourishing collection of other ancient plants north across the prehistoric Tethys Ocean, the research reveals.”
- SupportedThe fragment broke from northwestern Australia around 150 million years ago.Latest from Live Science: “a tiny fragment of Earth's crust that split from what is now northwestern Australia roughly 150 million years ago”
- SupportedThe fragment transported flowering plants north across the Tethys Ocean and ultimately seeded Southeast Asia’s tropical forests.Latest from Live Science: “After drifting northward for 100 million years, the microplate eventually collided with Southeast Asia, seeding tropical forests that evolved into the lush ecosystems found in this part of the world today”
- Partly supportedThe findings challenge earlier theories that the region’s flora evolved after the dinosaur extinction.Latest from Live Science: “The findings contradict previous theories that the fragment originated closer to what is now Southeast Asia and that Southeast Asia's tropical forests evolved sometime after the extinction of the dinosaurs around 66 million years ago.”
- SupportedThe WBB spent tens of millions of years near the equator, where it provided a refuge for ancient plant lineages to survive and diversify.Latest from Live Science: “the microplate spent tens of millions of years hovering near the equator, where it was humid and hot like it is today. This climate and the fragment's isolation provided a refuge where ancient plant lineages could survive and diversify”
- SupportedThe Indian Plate bumped into the WBB around 80 million years ago and altered its orientation; the WBB’s collision with Southeast Asia began around 50 million years ago.Latest from Live Science: “Around 80 million years ago, the Indian Plate bumped into the WBB, altering the fragment's orientation.”
- SupportedResearchers examined more than 3,000 plant fossils from Myanmar preserved in amber around 100 million years ago.Latest from Live Science: “For the study, Lamont and his colleagues examined more than 3,000 plant fossils from Myanmar that were preserved in amber around 100 million years ago.”
- SupportedThe fossils included at least 392 types of flowering plants, along with many other kinds of plants.Latest from Live Science: “They belonged to at least 392 types of flowering plants and a vast array of conifers, ferns, mosses, cycads and liverworts”
- SupportedByron Lamont said, “The rich tropical rainforest flora of [Southeast Asia] is not endemic but owes much of its biota to the great southern land, Gondwana,” in an email to Live Science.Latest from Live Science: “"The rich tropical rainforest flora of [Southeast Asia] is not endemic but owes much of its biota to the great southern land, Gondwana," study co-author Byron Lamont , a distinguished professor emeritus in Curtin University's School of Molecular and Life Sciences in Australia, told Live Science in an email.”
- SupportedLamont said the WBB did not strip Australia of its ancient flora because descendants of many plants found in the amber still exist in Northeast Australia.Latest from Live Science: “The WBB didn't strip Australia of its ancient flora, because the descendants of many plants found in the 100 million-year-old amber still exist in the country's Northeast, which is hot and humid, Lamont said.”
- SupportedLamont noted, “Its beautiful fossils, preserved in 3D, have long attracted interest for their novelty value alone and there has been much commercial interest in them, especially from Chinese traders.”Latest from Live Science: “"Its beautiful fossils, preserved in 3D, have long attracted interest for their novelty value alone and there has been much commercial interest in them, especially from Chinese traders," he noted.”
