A team of researchers from conicet found in the vicinity of the city of El Calafate, province of Santa Cruz (specifically in strata of the Chorrillo Formation), plant remains from an aquatic ecosystem from about 70 million years ago. In dialogue with the UNQ Science News Agencythe researcher at the Argentine Museum of Natural Sciences “Bernardino Rivadavia” and the main author of the article, Ezequiel Veraexplain what part of the findings correspond to fossil plants unknown until now in the Cretaceous for Argentina.
Together with researchers from Japan, the scientific team discovered plants of different types and sizes, of microscopic fossilstechnically called palynomorphs. For this, they carried out a chemical treatment that consists of disintegrating the rocks with acids and obtaining the organic remains. In this way, they found spores, pollen and leaf cuticles of previously unknown plants. The latter are layers located on the outside of the sheets and fulfill the function of waterproofing them. The cuticle is resistant and is sometimes the only information that allows us to identify that there was a plant in the investigated space. Vera explains: “All these plant remains found in a body of rock functioned as different lines of evidence that allow us to think vegetation as a whole”.
In addition, the researchers discovered other non-microscopic fossil remains, such as various types of leaves. Vera exemplifies: “One case is the leaves of the Nymphaeaceae family. There are some much more recent fossil records in the country, but this is the first time we have found them in rocks from the Cretaceous period”.
In addition, the paleobotanist claims that although it is common to find fossil remains of aquatic plants in the northern hemisphere, the same is not true in the southern hemisphere. The discovery of this group of plants in Argentina is important, “There is no other study so complete carried out in the country.” The discovery and study of the fossils was published in the journal Cstraight search.
Microscopic but informative
Microscopic fossils have an advantage over larger ones. As a bone: in a small sample you get a lot of information. So much so that those found in this research allow reconstruct the type of environment that existed millions of years ago in Patagonia.
The only problem with this type of fossil is finding them: the discovery depends on the type of rock in which the fossil was deposited. For example, in rocks that contain traces of carbon, fossil remains are more likely to be preserved; but not on a rock that was originally sand.
In this research, the team explains that it was the pollen grains that made it possible to establish that the fossils belonged to plants that inhabited the Earth 70 million years ago. Furthermore, in relation to the climate, after recognizing which plants existed in the Upper Cretaceous period, it was possible to know that It was neither extremely hot nor extremely cold. This discovery is due to the fact that the remains belong to plant families that currently do not belong to places with extremely cold or hot climates.
Even some pollen grains belonged to the conifer group, which inhabit humid environments. “As a result of this type of vegetation, we understand that there was a lot of humidity, which coincides with what was observed together with geologists: the site had shallow bodies of water and rivers.”
In this way, the scientific team carried out the environmental interpretation and advanced the knowledge of Patagonia for millions of years.
