The presence of fossil remains of dinosaurs more than 65 million years ago highlights Patagonia in the world. A group of researchers, which included an expert in entomology of the Nahuel Huapi National Park and CONICET, discovered the first fossil record of insects worldwide that lived in the last stage of the Mesozoic era, 70 million years ago. Yes, they lived with the last dinosaurs.
The discovery was made in the Chorrillo Formation, in the province of Santa Cruz. Due to its scientific importance, the work was published in the journal Communications Biologywhich is published by Nature Portfolio.
What the results mean
In dialogue with RÍO NEGRO Diarythe researchers explained that the analysis of the insects identified will allow progress in the reconstruction of ecosystems that preceded the current territory of Patagonia. Besides, would ratify the theory of plate tectonicswhich postulates that the Earth’s crust is fragmented and in permanent movement.
“It was a huge surprise to see that we had documentation of insects, which developed in water 70 million years ago. It was a great emotion to meet the bugs that fluttered with the dinosaurs before the meteorite fell that made them extinct,” said the CONICET senior researcher and first author of the article, Fernando Novasa RÍO NEGRO Diary.
Insects coexisted with dinosaurs 70 million years ago.
The area where the fossils were extracted is currently known as ranch “La Anita”, and is located about 30 kilometers south of the town of El Calafate. This site is a refuge for a vast natural heritage. Fossils of giant dinosaurs, both herbivorous and carnivorous, remains of frogs and fish, teeth of mammals, land and aquatic snails, and remains of plants have been found there.
“We knew about the presence of dinosaur fossils following studies carried out by geologists in 1980. For this reason, we decided to tour the sector in 2019. This is how we realized the formidable wealth of the site.. Not only did we find large dinosaur bones, ranging between 25 to 30 meters long, but also bird bones the size of a sparrow, molar teeth of mammals and more,” Novas explained.
The preservation characteristics of the Chorrillo Formation are exceptional. In the case of the insects reported in Communications Biologythree-dimensional fragments of heads, wings and scales of microscopic size were identified.
How insects were discovered
The discovery occurred by simple chance. It all started during the search for remains of pollen and spores among the sediments. This work was carried out by specialists, called palynologists.
“While the material was being processed, parts of something organic began to appear, which had belonged to some type of living creature. When we observed them through the microscope, we realized that they were part of the heads of insects,” explained Novas.
These difficult-to-characterize fragments were subjected to exhaustive comparisons with other fossil and living insects, in which entomologists from all over the country participated.
The researcher from CONICET and the Nahuel Huapi National Park, Julieta Massaferro, was summoned for crucial collaborative and interdisciplinary work. The woman from Bariloche is one of the few experts in the country in the study of chironomids, a family of diptera similar to mosquitoes, but with the particularity that they do not bite.
Scientist Julieta Massaferro from the Nahuel Huapi National Park collaborated with the analysis of the insect remains.
“I am a specialist in chironomids, but I do not work on such ancient groups. I usually focus on fossils around 20 million years old. For me it was an enormous challenge to address species that are already extinct,” Massaferro said in dialogue with RÍO NEGRO Diary.
Despite the work carried out, the probability that they are chironomids is proven at 80%. According to the scientist, this is because “there is no possibility of comparison with anything,” because there are no more records from that time.
“What was found in the formation are the larval heads, which are a maximum of two millimeters in length. After putting them under the microscope, we analyzed the structures. Each structure allowed the insect to be assimilated with a family and then we went on to determine the genus. It was a fairly long process,” he explained in reference to the identification process.
In addition to chironomids, lepidopterans (butterflies and moths) and ephemeropterans (mayflies, distant relatives of dragonflies) were found. There were also several incomplete specimens that could not be classified within the great diversity of insects.
A call to attention to the scientific community
The discovery of insects from 70 million years ago in El Calafate is of crucial importance. It is one of the oldest records of fossils preserved by the action of soil sediments. Although there are sets that date from similar periods, these are generally found covered by amber (fossilized resin).
Fernando Novas, head of the Laboratory of Comparative Anatomy and Evolution of Vertebrates (LACEV) of the Argentine Museum of Natural Sciences “Bernardino Rivadavia” (MACNBR, CONICET), expects that the identification of fossilized invertebrate fragments in rocks will begin to become more common in the future.
“It often happens that the specialist in these discoveries, the palynologist, may not notice that organic surplus that is not linked to the pollen grains that he hopes to discover. We encourage palynologists around the world to search the way we did because out there they can find the same surprise. Perhaps these cases can continue to appear. If not, then it means we were very lucky,” he added.
How is it related to plate tectonics?
The discovery of insects that lived with dinosaurs in the late Cretaceous period would reveal a unique connection between what is currently known as South America, Oceania and Antarctica. According to the researchers, The fossilized assemblages of El Calafate present similarities with fossils and living species from Australasia.
The group of researchers in the Chorrilos Formation, Santa Cruz. (Credit: Conicet)
The theory of Plate Tectonics assumes that, in those years, these large land masses would have still been united, or close to each other. Therefore, they would have shared very similar paleoenvironmental conditions, with a subtropical to tropical climate.
“The implication of this discovery is not only the discovery of a fossil that now does not exist. It was the time of Pangea, which is the period when all the continents were united. These insects likely lived in Patagonia, Australia and New Zealand. It is to this day that we find similar insects in those places,” explained entomologist Julieta Massaferro.
The chironomids are the clearest evidence. The identified specimens were assimilated to an endemic subfamily that existed in New Zealand and later disappeared.
Furthermore, it is believed that this class of diptera served as food for the Patagorhynchus pascuali, an ancestor of the current platypus whose remains were also discovered by CONICET scientists also in the Chorrillo Formation of Santa Cruz. The description of him was published in February by the magazine Communications Biology.
“This demonstrates a connection between the continents. The entire current southern hemisphere shared a very similar fauna and flora. In fact, the bugs that today live associated with the platypus in Australia are chironomids. And that association also lived 70 million years ago south of Calafate, in that ecosystem that has now disappeared,” explained Novas.