Scientists have discovered that an "alien plant" first found near a Utah ghost town 55 years ago doesn't appear to be related to any currently living family or genus.
Paleontologists first found fossilized leaf specimens of the plant in 1969 and named it Othniophyton elongatum, which translates to "alien plant." At the time, they believed the extinct species could be related to ginseng.
A more recent analysis, however, has challenged that hypothesis. Steven Manchester, curator of paleobotany at the Florida Museum of Natural History and Utah fossil expert, came across an unidentified plant fossil while visiting the University of California, Berkeley paleobotany collection. This plant fossil was well preserved, and had come from the same area as the alien plant leaves.
Manchester's research team analyzed the fossils and concluded they were from the same plant species, according to their study published Nov. 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. Around 47 million years ago, when the plants lived, the region was a huge lake ecosystem near active volcanoes. Lake sediment and volcanic ash slowed decomposition in fish, reptile, bird and plant remains, enabling some to be extremely well preserved.
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The researchers analyzed both fossils' physical features, and searched for living plant families that could be similar. Unlike the 1969 find, the specimen at UC Berkeley had leaves, flowers and fruits attached, which looked very different from those of plants related to ginseng. In fact, the researchers couldn't match the fossils to any of the over 400 families of flowering plants living today, and extinct families.
When scientists studied the original fossils in 1969, they were working only with leaves, not with flowers, fruits or branches; based on the arrangement of the leaves' vein patterns, they theorized the leaf structure could be similar to that of plants in the ginseng family. With the detail provided by the newer fossil, the researchers had a better picture of what the plant would have looked like and discounted the ginseng connection, but still couldn't pinpoint the plant's family.
A few years later, the Florida Museum of Natural History had access to new microscopy and artificial intelligence technology that enabled even more detailed viewing of the plant fossils. Micro-impressions of small, developing seeds were visible in the fossil's fruits. The research team could also see stamens — flowers' male reproductive organs — which in most plant species detach after fertilization.
"Usually, stamens will fall away as the fruit develops. And this thing seems unusual in that it's retaining the stamens at the time it has mature fruits with seeds ready to disperse. We haven't seen that in anything modern," Manchester said in a statement.
Comparing these traits to extinct families didn't result in any matches either, but this isn't the only species from the Green River Formation that has stumped scientists. This region has previously produced other plant fossils, like Bonanzacarpum fruit and Palibinia leaves, that have surprised scientists and ultimately led to the discovery of extinct groups.
