Fossils of unknown plants from about 240 million years ago discovered

Beyond the discoveries of small and giant animals of the past, there is a whole branch of paleontology dedicated to the study of fossils of prehistoric plants and vegetation. Their records account for the rich and complex ecosystems of millions of years ago and provide information on aspects such as the environment, climate and fauna-flora interaction, among other issues.

Now, a group of researchers has discovered, in the Argentine province of San Juan, two new species and a new genus of a type of plant known as bryophytes. The vegetables, from about 240 million years ago, belong to the Triassic period.

“Bryophytes are a group of very small plants, which are believed to be among the first to colonize the terrestrial environment. There are several types, such as mosses, liverworts, and hornworts. In this work, we were able to identify specimens of the first two”, Adolfina Savoretti, first author of the work and postdoctoral fellow at the National Council for Scientific and Technical Research (CONICET) of Argentina, explains to the CTyS-UNLaM Agency.

Currently, bryophytes are found in humid places with little light, although it is also found in drier environments. The problem, the researchers point out, is that it is difficult to recognize them in the fossil record.

“When we talk about plants, the species can be preserved in the amber of the trees, they can be dehydrated, charred and crushed by enormous pressure or leave a mark. In the case of our findings, the last two forms occurred, which are called impression-compression”, points out Josefina Bodnar, a member of the group and a researcher at the National University of La Plata in Argentina.

Researchers of the team working in the deposits in San Juan. (Photo: courtesy of the researchers)

The fact that the impression was preserved together with the compression, also allowed us to provide a lot of details that helped, later, when describing and studying the records. “In the case of these plants, even the sexual reproductive structures were preserved, which is extremely rare to find in the fossil record. All of this collaborates enormously in our analyses”, details Savoretti, postdoctoral fellow at the Austral Center for Scientific Research (CADIC, from CONICET) and professor at the Institute of Polar Sciences, Environment and Natural Resources (ICPA, UNTDF). The team is completed by Dr. Eliana Coturel and Marisol Beltrán, CONICET doctoral fellow.

The discovery of these ancient plants allows us to begin to understand what the climate was like at that time. “The moss that we discovered lived on a tree, which we still do not know what species it was – details Savoretti, who is a botanical biologist -. From previous research carried out by our working group, we know that there were both conifers and tree-seeded ferns in the area. But the most important thing is that these types of mosses are indicators of microenvironments with high humidity.”

In this line, Bodnar adds that the discovery of these bryophytes accounts for new scenarios for the scientific literature. “It had been suggested, in different works, that the climate in this region of Argentina, during the Triassic period, was very dry. The discovery of these fossils tells us that not everything was the same, but that there were, obviously, periods with higher levels of humidity”, highlights the researcher. (Source: Nicolás Camargo Lescano, CTyS-UNLaM Agency)