Scientists have uncovered that an 'alien plant' first identified near a ghost town in Utah 55 years ago does not belong to any currently recognized family or genus.
Paleontologists initially discovered fossilized leaf specimens of the plant in 1969, naming it Othniophyton elongatum, which translates to 'alien plant.' At that time, researchers believed the extinct species might be related to ginseng.
However, a recent analysis has called this hypothesis into question. Steven Manchester, curator of paleobotany at the Florida Museum of Natural History and an expert on Utah fossils, found an unidentified plant fossil while examining the paleobotany collection at the University of California, Berkeley. This well-preserved fossil originated from the same area as the alien plant leaves.
Manchester's research team conducted an analysis of the fossils, concluding they belonged to the same plant species, as detailed in their study published on November 9 in the journal Annals of Botany.
Both fossil specimens were excavated from the Green River Formation in eastern Utah, near the former town of Rainbow. Approximately 47 million years ago, when these plants thrived, the region was a vast lake ecosystem near active volcanoes. The combination of lake sediment and volcanic ash contributed to the exceptional preservation of fish, reptile, bird, and plant remains.
The researchers examined the physical characteristics of both fossils and searched for living plant families with similar traits. Unlike the 1969 discovery, the specimen at UC Berkeley included leaves, flowers, and fruits, which appeared markedly different from those of ginseng-related plants. In fact, the team could not match the fossils to any of the over 400 families of flowering plants that exist today or to any known extinct families.
When scientists analyzed the original fossils in 1969, they only had leaf specimens to work with, leading them to theorize that the leaf structure bore similarities to plants in the ginseng family. With the additional details provided by the newer fossil, researchers gained a clearer understanding of the plant's appearance and dismissed the ginseng connection, yet they remained unable to classify the plant's family.
A few years later, advancements in microscopy and artificial intelligence technology at the Florida Museum of Natural History allowed for even more detailed examinations of the plant fossils. Micro-impressions of small, developing seeds were observed in the fossil's fruits. The research team also identified stamens—male reproductive organs of flowers—which typically detach after fertilization.
Manchester noted, 'Usually, stamens will fall away as the fruit develops. This specimen is unusual in that it retains the stamens while having mature fruits with seeds ready for dispersal. We haven't seen that in any modern species.'
Despite comparing these characteristics to extinct families, no matches were found. The Green River Formation has previously yielded other enigmatic plant fossils, such as Bonanzacarpum fruit and Palibinia leaves, which have similarly puzzled scientists and led to the identification of extinct groups.