BY TIM NEWCOMB JAN 10, 2024

Researchers studying fossilized wood on Barro Colorado Island in the Panama Canal recently discovered that an Early Miocene mangrove forest once covered the area.

A  volcanic flow likely buried and fossilized the trees in a single event.

Those trees represent a species of mangrove previously unknown to science.

Researchers studying on Barro Colorado Island in the Panama Canal recently uncovered an entire lost ancient mangrove forest over 22 million years old, thanks to the discovery of the fossilized—and previously unknown to science—Sonneratioxylon barrocoloradoensis mangrove species. The team published a study documenting their discovery in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

According to the paper, adiometric analysis of the fossils dates the mangrove forest—including the 121 fossilized wood specimens located on the island—to the Aquitanian stage of Early Miocene. During this period, central Panama was part of a long and narrow peninsula connected to North America but and separated from South America, and was host to intense volcanic activity.

That volcanic activity was the likely demise of the forest. Sedimentary and rock analyses suggest that the fossilized trees once grew in either river or ocean environments until a single volcanic event buried the forest. 

Researchers from the Smithsonian Tropical Research Institute said in the study that the wood anatomy of these mangroves indicates that they are similar to a type of mangrove native to Southeast Asia. The team named this newly discovered species after the island where it was found, and believe that S. barrocoloradoensis generally grew to a height of 82 feet tall—although, the tallest specimens could stretch upward of 131 feet, easily outpacing modern mangrove forests in terms of towering reach. 

The authors wrote that studying the site where the specimens were found has lead them to believe “that the fossil wood assemblage on Barro Colorado Island comprised a mangrove forest growing along the coast of the volcanic chain of central Panama.”

Mangrove forests are known to grow in tropical and subtropical locations. They can’t handle freezing temperatures, but the dense, tangly root systems cope well with fluctuating tides, making them a common site on coastlines and riverbanks. Salt water isn’t an issue for mangroves, which can filter the salt (along with other sediment) and thrive in some of the saltiest conditions available. 

Barro Colorado Island became a research hub after it formed in 1913—during the creation of Lake Gatun—as part of the Panama Canal construction. The 9-square-mile island is home to some of the oldest tropical research stations in the world, as the “rainforest-covered living laboratory” allows for unique opportunities to study biology, ecology, and animal behavior. 

Barro Colorado Island’s history already features over 100 years of research, but locating a previously unknown mangrove species and opening up an entirely new world of lost forests from over 22 million years ago is a real feather in its cap.