2023-10-06 19:45:37
A paleobotany team set out to find out when modern groups of conifers emerged, with characteristics different from those of other older trees, and to delve deeper into the initial evolution of these groups.
“When? As? Where?”. Questions usually crowd the minds of paleontology researchers who, in their eagerness to complete the “photo album” of the history of planet Earth, investigate and discover how terrestrial and aquatic ecosystems were formed millions of years ago. and millions of years.
On that path were (and are) Josefina Bodnar, a researcher at the National University of La Plata (Argentina) and her team who, in a recent work, investigated the conifers of the Triassic period located in what is now Argentine territory. The study has been published in Ameghiniana, the journal of the Argentine Paleontological Association, and involved the review of the anatomy and systematic affinity of some of the plant remains from that geological period.
“All the continents were united in a large land mass or supercontinent, called Pangea, but over time they were divided into two parts, Gondwana and Laurasia,” explains Bodnar, a doctor in Natural Sciences. “The first included what is now South America, Africa, Australia, New Zealand, Antarctica and India, and we focused on this particular area for research.”
With a special emphasis on the Triassic period of the Mesozoic era (in terms of time, between 251 million years ago and 200 million years ago), Bodnar and his team set out to find out when modern conifer families emerged. The question was not simple, especially if one took into account, as the scientists themselves explain, the fossil material they have so far.
“Let’s start with the fact that conifers were not a dominant group in those ecosystems. For this same period there are different fossils that could belong to conifers, but mostly many fragments of wood and few fossils of leaves, cones or reproductive structures,” details the CONICET scientist. “Then the question was why there was so little record of leaves and pine cones and so much of wood and from solving that question, when did the first modern families of this group of plants appear.”
Thanks to the laborious task of investigating and reviewing the available fossil logs, researchers are certain about how some woods could be prehistoric conifers or not. “We checked the fossil record of these conifers, we studied the reproductive leaves that were assigned to these families, we analyzed the characteristics and organs and, in this way, we were able to consolidate the record,” says Bodnar.
Anatomy of wood cells under the microscope. (Image: the research team)
Wait… plant fossils?
Yes, the answer is affirmative: there are an enormous amount of fossils of plants from millions of years ago in the world. Giovanni Nunes, CONICET fellow based at the Egidio Feruglio Paleontological Museum and also author of the work, explains it this way.
“When wood or other parts of trees become fossilized, the anatomy is studied, just as in a current plant, if they are well preserved. What we try to look for, using different methodologies and techniques, is what characters could be useful to see if these woods were from conifers or other plants with seeds,” he says.
The confusion about whether it was one species of tree or another – remember, we are talking about species that are millions of years old – lies in the fact that you never have the complete plant, but only fragments. “In some fossils, the wood was the same as that of a conifer, but the leaves looked like those of a fern and had seeds. In any case, only with the wood we could rule out that they were ferns with seeds or more primitive conifers,” adds the intern.
The team says that they began the study during a pandemic, which meant that they could only analyze the samples housed in the collections of the La Plata Museum or the Egidio Feruglio Museum in Trelew, while the rest had to be reviewed from the bibliography or from photos available.
“One of the problems with this is that obstacles arose since there are different criteria for defining the characters and traits that are studied. Not everyone calls all aspects the same way and there are different terminologies for the same thing, which is why it was a complex problem to overcome,” Nunes contributes in this sense.
These challenges also included that many technical terminologies are given from current species, so in fossils they cannot be seen in the same way, or, in several situations, parts that had to be described for the first time. “In some fossils, we could not directly analyze them because they are very poorly preserved,” clarifies the intern.
Beyond the setbacks or technical challenges, the balance is good, in addition to leaving more questions than answers. “All this methodology motivated us to review more. It is important to unify the criteria, in these cases. We began to think that there were many logs that could be from other groups because for many extinct plants it is not known what their trunks and wood were like,” Bodnar postulates. There remains, he assures, the possibility of evaluating each of the registered characters more intensively.
The line of research therefore remains open, awaiting possible new findings in the future. (Source: Nicolás Camargo Lescano (CTyS-UNLaM Agency))
#Searching #origin #conifers