Prototaxites: The Ancient Giants That Ruled the Earth Before Trees

Prototaxites is one of palaeontology's most enduring mysteries. Fossilised remains found in rocks between 420 and 370 million years old, some reaching up to eight metres tall, show that these organisms dwarfed every living thing around them — Earth's first skyscrapers, predating even the first trees. Originally classified as an ancient tree trunk, and later as a giant fungus, neither explanation ever fully satisfied scientists. A recent study by University of Edinburgh researchers put the fungal hypothesis to the test using specimens from Scotland's Rhynie Chert, an extraordinarily well-preserved 400-million-year-old deposit formed by ancient hot springs — a kind of prehistoric Pompeii.

Using advanced microscopic, chemical, and machine learning analysis, the team found that Prototaxites bore none of the molecular signatures associated with fungi, plants, or animals. The tubes making up its trunk-like structure were too distinct from fungal anatomy, and key fungal molecules like chitin were entirely absent. Further geochemical analysis confirmed the organism didn't match any known group of life. The conclusion is as remarkable as it is humbling: Prototaxites was likely a eukaryote, but one belonging to an entire lineage that has since vanished from the Earth — a ghost group, leaving behind only this single enigmatic fossil as proof it ever existed.

Read the full piece on RTÉ Brainstorm here.