A freshwater species that dates back to the early Cretaceous period may be the world’s oldest flowering plant, according to researchers. The remarkable discovery challenges the previously held consensus on the evolutionary history of flowering plants.
David Dilcher, a paleobotanist at Indiana University, led a group of researchers to analyze more than 1,000 fossilized plant fragments. These fossil remains were first discovered over a 100 years ago in limestone deposits in the Pyrenees and Iberian Mountains in Spain. According to Dilcher, previous analysis of these fossil fragments had been poorly understood and misinterpreted, where botanists had failed to grasp its true significance.
In their latest findings, detailed in the journal Proceedings of the National Academy of Sciences, researchers have identified an aquatic plant, named Montsechia vidalii, that they believe to be between 125 and 130 million years old. The flower dates back to the Cretaceous period, where dinosaurs like the brachiosaurus and iguanodon roamed the Earth.
Researchers applied hydrochloric acid on a drop-by-drop basis to reveal its stem and leaf structure. They bleached the plant’s cuticles with a mixture of nitric acid and potassium chlorate to see their shape. The fossil fragments were then examined using a stereo microscope, light microscope and scanning electron microscope.
“A ‘first flower’ is technically a myth, like the ‘first human,’” said Dilcher, in a statement. “But based on this new analysis, we know now that Montsechia is contemporaneous, if not more ancient, than Archaefructus,” which was previously named the most ancient flowering plant.
Illustrations based on fossilized remains of Montsechia vidalii. Image credit: Oscar Sanisidro
M. vidalii is thought to have grown and pollinated in freshwater lakes. Researchers note that it didn’t have petals, but is classified as a flowering plant – known as an angiosperm – because it contained seeds enclosed within a fruit. The species carried out its entire lifecycle underwater.
“This discovery raises significant questions about the early evolutionary history of flowering plants, as well as the role of these plants in the evolution of other plant and animal life,” Dilcher explained.
Botanists had previous thought that flowering plants emerged on dry land and moved into water. However, Dilcher's findings question the evolutionary path of flowering plants.
“This is a fascinating and provocative analysis of the new fossils,” Sam Brockington, a plant sciences researcher from Cambridge University, told The Guardian. “It has always been difficult to say whether the first flowering plants emerged in aquatic conditions, but this paper emphasises how important aquatic environments were for the earliest flowering plants.”
But not everyone is convinced that flowering plants first originated in water. Botanist Taylor Feild from James Cook University told Science Magazine that there might be a potential bias towards aquatic plants as they’re more likely to be preserved in the fossil record than land plants, but said that the research “offers fresh evidence that early angiosperms invaded freshwater aquatic habitats.”