In the ancient prehistory of Earth, there is a chapter that waits to be told known as Romer’s gap. Researchers have identified a hiatus in the tetrapod fossil record between 360 million and 345 million years ago, after fish had begun to adapt to land and more than 80 million years before the first dinosaurs.
While mysteries remain about evolution’s experiments with living things during that 15-million-year gap, a fossilized tree described in a new paper offers greater insights to some of what was happening during this period in nature’s laboratory.
Named Sanfordiacaulis densifolia, the tree had a six-inch diameter with a nearly 10-foot-tall trunk composed not of wood, but of vascular plant material, like ferns. Its crown had more than 200 finely striated, compound leaves emanating from spiral-patterned branches that radiated 2½ feet outward. Robert Gastaldo, a geology professor at Colby College in Maine who is an author of the study, which was published Friday in the journal Current Biology, compared it to “an upside-down toilet brush.” Comically top-heavy, even Seussian, the tree most likely remained upright by intertwining its branches with those of neighboring trees.
“This is a totally new and different kind of plant” than had been found in the Late Paleozoic Era, said Patricia Gensel, a professor of biology at the University of North Carolina at Chapel Hill and another author of the paper. She added, “We typically get bits and pieces of plants, or mineralized tree trunks, from Romer’s Gap. We don’t have many whole plants we can reconstruct. This one we can.”
The tree was unearthed near Valley Waters, New Brunswick, in an active private quarry within Canada’s Stonehammer UNESCO Global Geopark. (A new fossil museum will open in the village later this year.) The area is part of the 350-million-year-old Albert Formation, a geological layer that has also yielded fossilized fish and trace fossils. Although partial fossils of the same tree species had previously been found, the new discovery represents the only such fossil whose trunk and crown were preserved together.
