What did scientists find

Trees in the ancient mangrove forest reached a height of 40 meters. Researchers first discovered the fossils during a geological expedition on Colorado’s Barro Island in 2018. The island is located in Panama’s man-made Gatun Lake, where thousands of ships pass through the Panama Canal each year.

This area was once part of hilly terrain; It was partially flooded when engineers dammed the Chagres River to build a canal in 1913, and it was declared a nature reserve in 1923. Today, the island’s tropical forests are among the most intensively studied in the world.

We never thought fossil wood could be in Barro Colorado.
– Scientists say that none of the numerous researchers who worked on the island in the last century reported on this issue.

Mangrove fossils are extremely well preserved, so much so that they can be difficult to distinguish from other examples of recently deceased trees, says geologist Carlos Jaramillo of the Smithsonian Tropical Research Institute in Panama. This is because the volcanic eruption slows decomposition by burying trees, effectively freezing the landscape over time.

Camila Martínez Aguilón of EAFIT University in Colombia, one of the authors of the study, said that the cellular structure of the fossils was mineralized and remained intact over many years, providing researchers with a “rare and wonderful opportunity to travel back in time.”

Researchers examined 121 samples of petrified wood lying in a small stream. 50 of them belonged to a previously unknown species, which they named Sonneratioxylon barrocoloradoensis. The newly discovered fossil species resemble mangrove trees that grew in Southeast Asia, Australasia, a region that includes Australia, New Zealand and some nearby islands, and parts of present-day tropical Africa.

Researcher Karen Cardenas sits near the fossil mangrove forest on Colorado’s Barro Island / Photo: Christian Ziegler

But old the forest was much taller than modern mangrovesAccording to research. While the crown height of most living mangrove trees reaches approximately 13 meters, S. barrocoloradoensis reaches 25-40 meters in height.

Ancient trees likely developed the same survival strategies as today’s mangroves, preferring slightly brackish waters to the highly saline waters of the ocean.

The mangrove fossils were all in a similar state of preservation; This led researchers to believe that the forest was destroyed by a single volcanic eruption that covered the entire landscape with mud.