Geology 38, 295–298 (2010)

Credit: GEOL. SOC. AM.

A study of more than 100 fossilized trees in the southern Andes of Argentina has allowed researchers to reconstruct the trees' habitat and deduce how they survived their harsh environment some 300 million years ago.

Silvia Césari at the Bernardino Rivadavia Museum of Natural Sciences in Buenos Aires and her colleagues analysed specimens from an ancient forest 3,000 metres above sea level. They found only one dominant tree species. Sedimentary deposits and volcanic rocks show that the area was frequently flooded and affected by volcanic activity, raising questions about the trees' survival strategy.

The team found small rootlets inside several fossils, suggesting that seedlings had developed on previously felled trees. These rootlets contain intercellular spaces (pictured above), which would have been filled with air to maintain an oxygen supply — a common feature of extant plants in areas prone to flooding. The authors say that decaying trees may have acted as “nurse logs” for saplings.