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They discover a “dwarf” crocodile from 148 million years ago

An extinct species has been discovered that could be understood evolutionarily as a grandfather of today’s crocodiles. It measured only 70 centimeters in its adulthood and constitutes one of the few crocodiles that inhabited the mainland along with dinosaurs at the end of the Jurassic period.

In a great joint paleontological expedition of Chilean and Argentine scientists, the remains of the skeleton of the aforementioned 148 million-year-old crocodile were discovered in the Patagonian Mountains of southern Chile, at 1500 meters high, which required a great logistical operation.

The study has been published in the academic journal Scientific Reports, of the Nature group.

Dr. Fernando Novas, head of the Laboratory of Comparative Anatomy and Evolution of Vertebrates of the Argentine Museum of Natural Sciences (LACEV-MACN) and researcher at CONICET, indicated: “We found part of the skull, the vertebral column and the lower extremities of this animal”.

“This was a small crocodile no more than 70 centimeters long, in clear contrast to the six meter long marine crocodiles that were thriving back then in what is now the province of Neuquén, which was previously covered by the sea. of the ascent of the Cordillera de los Andes ”, reported Novas, lead author of the study.

In this sense, the paleontologist Federico Agnolin, a researcher at MACN, CONICET, the Azara Foundation and co-author of this study, added to the CTyS-UNLaM Agency that “at that time, in the seas, there were predatory crocodiles, but, in On the other hand, the Burkesuchus was modest, small, although it represents all a radiation of the terrestrial crocodiles, of which very few are known worldwide ”.

“Although we could not find the snout of this species, its small size, as well as its small and sharp teeth, make us think that the Burkesuchus was a small carnivore that possibly fed on invertebrates such as insects or crustaceans, or small vertebrates as they could be the fish. What we know of Burkesuchus indicates that it did not have the ability to capture large prey, or tear large chunks of meat as living crocodiles do, “said Agnolin.

Reconstruction of Burkesuchus mallingrandensis. The bones highlighted in red were those found of this new species. (Image: CTyS-UNLaM Agency)

Fernando Novas asserted that “Burkesuchus shows not only how the radiation of crocodiles that lived on land was produced, between the legs of the dinosaurs, but also the shape of their skull, their hind legs and the rest of their body , shows us that it was on its way to give rise to modern crocodiles that inhabit lagoons and rivers ”.

“For example, you can see a modification in the skull, more precisely in the closure that it had in the ear region to be able to submerge in water, so Burkesuchus is something like the grandfather of modern crocodiles and is showing stages of the evolution that are very little known worldwide ”, highlighted the head of LACEV-MACN.

Dr. Novas indicated that the discovery of this new species joins a list of extremely interesting findings that LACEV has been making for almost a decade, in collaboration with Dr. Manuel Suárez and his team from the Andrés Bello University in Santiago Chile .

Burkesuchus mallingrandensis is the name with which the researchers baptized this new animal, which means “Burke’s crocodile from Mallín Grande”. “The name we chose to identify this new crocodile – explained Novas – pays tribute to the American Coleman Burke, lover of Patagonia and passionate about paleontology, who played a fundamental role in the various activities of our laboratory. Coleman and his wife Susan gave us their support and enthusiasm to carry out explorations and new paleontological discoveries, including the crocodile that today bears their name. “

The discovery of this little grandfather of the crocodiles occurred at 1500 meters high. There, a paleontological site from the Jurassic period emerges. This place was discovered in 2004, when the fossil remains of the herbivorous dinosaur Chilesaurus diegosuarezi were extracted.

Almost ten years later, in 2013, the expedition was carried out in which the remains of this small crocodile from the mainland appeared. Marcelo Isasi, LACEV-MACN and CONICET technician, said that this operation required great logistics.

“This expedition involved the transportation and use of machinery, tools, labor and camping supplies. We had to cross a river to reach the outcrops, which had no bridge and was very overgrown, ”Isasi said about one of the most difficult points of the operation.

Isasi told the CTyS-UNLaM Agency that “from the camp we formed in the mountain, we had a journey of an hour and a half on horseback to reach the site, located at the top.”

“It was wonderful to ride surrounded by glaciers and that landscape, but it could also be very dangerous, since you have to cross large areas of ice,” said the technician.

The first time he arrived at the site, Federico Agnolin found the remains of this crocodile and warned the rest of the team to come closer. “When we arrived, we saw that it was small exposed bones,” Isasi said.

In order to rescue these fossils, machinery was used to cut the rock fragment where they were housed. “Look, it’s the coconut skull,” were the words Agnolin said as he showed the remains to the other team members. “There, we realized that the campaign was already a success,” recalled Marcelo Isasi.

The extraction of the crocodile lasted two days and during the rest of the campaign, more fossils of the Chilesaurus dinosaur continued to be found. Crocodile preparation was carried out at MACN. It took several months to separate the hard rock from these fossils and, later, the study of these materials began, for which a 3D scan of each piece found was carried out, in order to develop the complete skeleton of this animal.

Researcher Sebastian Rozadilla from LACEV and CONICET also commented to the CTyS-UNLaM Agency about the difficulty of this expedition: “If it rained too much, it was not possible to cross the river. Sometimes it was very cold or it snowed and then we had to wait a couple of days until the ground was uncovered from the snow and we could continue with the search for fossils.

“All that adventure resulted in this fantastic find. We see that the findings in Patagonia reaffirm that the south of our continent is of great relevance for paleontology worldwide ”, highlighted Rozadilla. And he added: “Animals like Burkesuchus will help change our understanding of the evolution of the reptiles that dominated the Earth in the Mesozoic Era.”

Researchers Gabriel Lio from LACEV-MACN, Manuel Suárez from the Andrés Bello University of Chile, Rita de la Cruz from the National Geology and Mining Service of Chile, Ismar de Souza Carvalho from the National University of Rio de Janeiro and David Rubilar-Rogers of the National Museum of Natural History of Chile. (Source: CTyS-UNLaM Agency)

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