Fossils discovered on Barro Colorado Island suggest central Panama was once home to a vast mangrove forest that was preserved when a volcanic mudflow buried it 23 million years ago.

An ancient mangrove forest with trees that towered up to 130 feet high has been discovered over 20 million years after a volcanic mudflow smothered it in what is now Panama, a new study reveals.

Researchers first discovered the fossils in 2018 during a geological expedition on Barro Colorado Island (BCI). The island sits in Panama’s human-made Gatun Lake, which thousands of ships cross every year as they cruise through the Panama Canal. BCI once formed part of a hilly landscape that became partly submerged in 1913, when engineers dammed the Chagres River to build the canal, and was set aside as a nature reserve in 1923. Today, the tropical forests of BCI are some of the most intensively studied in the world.