Jade Small
Jade Small
January 3, 2025 ·  3 min read

Groundbreaking Discovery: Lost Forest From 22 Million Years Ago Has Suddenly Resurfaced

In an extraordinary breakthrough, researchers studying Barro Colorado Island in the Panama Canal have uncovered fossilized remains of a 22-million-year-old mangrove forest. This ancient ecosystem, documented in early 2024 in the journal Palaeogeography, Palaeoclimatology, Palaeoecology, has revealed a previously unknown mangrove species, Sonneratioxylon barrocoloradoensis. The discovery sheds light on the intricate interactions of prehistoric ecosystems and their environments, offering valuable insights into Earth’s ancient past.

The Magnitude of the Discovery

A fossilized wood sample discovered on Barro Colorado Island in Panama.
Image credit: Christian Ziegler

In February 2024, scientists from the Smithsonian Tropical Research Institute announced the identification of 121 fossilized wood specimens from an ancient mangrove forest. These fossils date back to the Aquitanian stage of the Early Miocene epoch, approximately 22 to 23 million years ago. At that time, central Panama was a narrow volcanic peninsula, which created a unique setting for tropical ecosystems to flourish.

A New Species: Sonneratioxylon barrocoloradoensis

The newfound fossil mangrove species grew taller than the mangroves that grow today in Southeast Asia (pictured).
Image credit: Reinhard Dirscherl via Getty Images

second image: https://www.livescience.com/planet-earth/plants/23-million-year-old-petrified-mangrove-forest-discovered-hiding-in-plain-sight-in-panama

The most remarkable aspect of the find is the identification of a previously unknown mangrove species. Named Sonneratioxylon barro coloradoensis, this ancient tree bore striking similarities to the modern Southeast Asian mangrove genus Sonneratia. What makes it even more fascinating is its size—these trees stood at an average height of 25 meters (82 feet), with some reaching 40 meters (131 feet), making them giants among mangroves, both ancient and modern.

The Role of Volcanic Eruptions in Fossil Preservation

anatomical characteristic of wood
Image credit: Camila Martinez

The fossils were preserved due to volcanic activity prevalent in the region during the Early Miocene. A volcanic eruption triggered a lahar, a destructive flow of mud, water, and debris, which buried the mangrove forest. This rapid burial shielded the wood from decomposition, resulting in exceptional fossilization. Radiometric dating techniques confirm the timing of this preservation, placing the fossils at around 22 million years old.

Evidence of a Broader Mangrove Habitat

mangrove forest growing along coastline
Image Credit: Steve Paton

The discovery suggests that mangrove species like Sonneratia were once more widespread. Today, their descendants are primarily found in Southeast Asia. This fossil evidence provides a missing link, showing that such mangroves thrived in prehistoric tropical regions of the Americas before environmental changes caused their extinction in the Western Hemisphere.

Barro Colorado Island: A Geological and Ecological Treasure

Barro Colorado, a man-made island in the middle of the Panama Canal
Courtesy of Smithsonian

Barro Colorado Island, a research hub since its formation during the Panama Canal’s construction in 1913, continues to reveal significant scientific insights. Its geology, shaped by tectonic activity and volcanic eruptions, provides an exceptional context for studying ancient tropical environments. This latest discovery adds to the island’s legacy as a site of pivotal research into Earth’s history.

Clues to Ancient Climate and Ecosystem Dynamics

during collections of fossil samples
Image Credit: Victor Vasquez

The preserved mangrove forest offers a snapshot of the Earth’s climate and ecological conditions during the Early Miocene epoch. The fossilized trees indicate a warm, humid environment, conducive to the development of expansive mangrove ecosystems. Such insights help researchers understand how ecosystems responded to past climatic shifts, informing predictions about the future impacts of climate change.

Looking Forward: The Future of Fossil Research in Panama

researcher cut segments of the  fossils for lab analysis
Image Credit: Camila Martinez

This discovery opens new avenues for studying ancient tropical ecosystems. Researchers plan to conduct further excavations in the region, aiming to uncover additional fossilized remains that can provide a more detailed picture of the Miocene epoch. This research has the potential to deepen our understanding of both the history and resilience of mangrove forests.

Conclusion: A Glimpse into a Lost Ecosystem

researcher sits on the mangrove  fossil
Image Credit: Victor Vasquez

The discovery of a 22-million-year-old mangrove forest on Barro Colorado Island is a remarkable achievement, offering an unprecedented look into the past. The identification of Sonneratioxylon barrocoloradoensis highlights the diversity and adaptability of mangrove ecosystems through time. For further reading, explore the Smithsonian Tropical Research Institute’s blog or the detailed findings published in Palaeogeography, Palaeoclimatology, Palaeoecology.

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