Country music singer and philanthropist Dolly Parton has an unlikely new namesake: a 460-million-year-old moss that may have been among the first plants to grow on earth. University of Oregon geologist Greg Retallack discovered the fossil footprints of Dollyphyton boucotil, along with several other species of mosses, lichens, small plants called liverworts, in 460 million year old rocks of eastern Tennessee. The rocks that held the fossils once stood a few miles from Dollywood Theme Park in Parton, Sevier County, Tennessee. This is how a country musician finds herself with her name on some kind of extinct moss.
The rock slabs, strewn with the imprints of long-dead plants and animals, have their own colorful history. In 1942, the United States had just entered World War II, and victory depended on millions of factory workers producing planes, tanks, ships, munitions, uniforms, and more. These factories needed more electricity. Part of the solution came in the form of hydroelectric dams, like the Douglas Dam on the French Broad River in Sevier County, Tennessee.
“At the start of World War II, Congress approved the Douglas Dam bill to provide power for the war effort, particularly to produce the aluminum needed to build airplanes. TVA workers worked hard day and night, and the dam was completed in just over a year,” says the Tennessee Valley Authority website for the dam. “Work on the Douglas Dam began in February 1942 and were completed on a disastrous schedule in just 12 months and 17 days – a world record for projects of equivalent size.”
And while TVA workers were hard at work, they unearthed huge slabs of rock that formed when North America was still part of a supercontinent called Laurentia 460 million years ago. Back then, during what paleontologists call the Ordovician period, shallow seas covered most of today’s land. Jawless armored fish called ostracoderms patrolled these seas, where trilobites bristled with spines and nodules to protect themselves from being eaten. Brachiopods – shelled animals that look, at first glance, like weird clams – thrived with colonies of tube-shaped filter feeders called graptolites. The first coral reefs had begun to form, and relatives of modern starfish appeared.
It was a world dominated by the sea – but some strange little plants had started to move towards land. And the Ordovician rocks of eastern Tennessee record the only evidence we have of these early land plants. A few sections of the rock ended up at the University of Cincinnati and the Smithsonian Institution in the 1940s, and that’s where Retallack and his colleagues found them and took a closer look.
“This is another example of how dusty old museum collections can yield truly extraordinary new discoveries,” he said in a recent press statement. Earlier paleontologists had spotted the tiny invertebrate animal shapes in the rock, but Retallack was the first to find the plants. In a way, paleontologists had been looking for them for quite some time, because the sudden appearance of land plants left a mark on the world that nothing else could explain. But until recently, no one had found real fossils of the plants themselves.
The collection of mosses, lichens, and liverworts would have been tiny things clinging to the earth near the shore. They probably evolved from green algae and, like their modern relatives, they didn’t produce flowers and didn’t have complicated ways of moving water around their bodies. But these humble little plants sounded the death knell for much of the life in the seas they had left behind.
Plants absorb carbon dioxide from the atmosphere, which is why forests are such good carbon sinks. But when new types of plants suddenly moved from land to water, together they absorbed enough carbon dioxide to trigger a drastic global cooling. Geologists and paleoclimate researchers have found evidence of ice ages in sediments and rocks dating to around 447 to 444 million years ago, and paleontologists note that most of the fossil species that defined the ‘Ordovician disappear at about the same time. This is the first mass extinction for which we have evidence, and it killed around 85% of life on Earth.
But some of those early land plants held on, and their descendants are all around us today. Some are still tiny non-vascular single plants, such as mosses and liverworts and Japewiella dollypartoniana, a species of Appalachian lichen discovered in 2015 and also named after Dolly Parton. Others evolved into the magnolia, dogwood, willow and oak that fill his songs.
Retallack published his findings in the journal The paleobotanist.