Indiana University paleobotanist David Dilcher has identified a freshwater plant between 125 and 130 million years old, as one of the earliest flowering plants on Earth.
The finding, published this Monday in the ‘Proceedings of the National Academy of Sciences’, represents an important change in the supposed shape of one of the first flowers on the planet, known as angiosperms.
"This discovery raises important questions about the early history of plant evolution, as well as the role of these plants in the evolution of other plants and animal life," says Dilcher, professor emeritus in the Department of Geological Sciences at the Faculty. Bloomington Institute of Arts and Sciences of the IU, in a statement released by the university.
The aquatic plant, ‘Montsechia vidalii’, once grew abundantly in freshwater lakes in what are now mountainous regions of Spain.
The fossils of the plant were discovered more than a hundred years ago for the first time in the limestone deposits of the Iberian Mountain Range in central Spain and the Montsec mountain range in the Pyrenees, between Lérida and Huesca, near the border with France.
It has also been previously proposed as one of the first flowers 'Archaefructus sinensis', an aquatic plant found in China. "A 'first flower' is technically a myth, like the 'first human,' says Dilcher, an internationally recognized expert on the anatomy and morphology of angiosperms who has studied the emergence and spread of flowering plants for decades.
But based on this new analysis, we now know that ‘Montsechia’ is contemporary, if not older, than ‘Archaefructus.
He also explains that the fossils used in the study were "little known and even misinterpreted" during previous analyzes.
"The reinterpretation of these fossils offers a fascinating new perspective on an important mystery in plant biology," adds Donald H. Les, professor of Ecology and Evolutionary Biology at the University of Connecticut, who is the author of a paper on the discovery in the journal 'PNAS'.
The conclusions of this work are based on a careful analysis of more than a thousand fossilized remains of ‘Montsechia’, whose stems and leaf structures were extracted from the stone by applying hydrochloric acid in a drop by drop basis.
The plant's cuticles - the protective film covering the leaves that revealed their shape - were also carefully bleached using a mixture of nitric acid and potassium chlorate. A CONTEMPORARY FLOWER WITH DINOSAURS The examination of the samples was carried out under a stereomicroscope, light microscope and scanning electron microscope.
The age of the plant between 125 and 130 million years was determined by comparing it with other fossils from the same area, particularly freshwater carphytic algae, which places 'Montsechia' in the Barremian era of the early Cretaceous period, making this contemporary flowering plant with dinosaurs such as the brachiosaurus and the iguanodon.
The precise and meticulous analysis of fossilized structures remains crucial for paleobotany, unlike other biological fields, due to the current inability to know the molecular characters of ancient plants for millions of years, Dilcher emphasizes.
This careful examination was particularly important at ‘Montsechia’ as most modern observers would not be able to recognize the fossil as a flowering plant.
"Montsechia does not have obvious flower parts such as petals or nectar-producing structures to attract insects and lives its entire life cycle under water," he details.
"The fruit contains a single seed - the defining characteristic of an angiosperm - that it is born the other way around," he explains.
In terms of appearance, according to Dilcher, ‘Montsechia’ resembles its more modern offspring, identified in the study as ‘Ceratophyllum’, a dark green aquatic plant that is often very popular as decoration in aquariums.
"There is still a lot to discover about how some early species of seed plants eventually gave rise to the huge and beautiful variety of flowers that now populate almost every environment on Earth," he concludes.Ecoportal.net