Bolivia is one of the countries with the greatest wealth and variety of fossilized footprints. With the peculiar constitution of its soils, it keeps hundreds of traces on its land that tell us about a past Earth.
The Argentine paleontologist Sebastián Apesteguía arrived in the paradise of paleontology eleven years ago and found hundreds of footprints of what he believed were dinosaurs. However, after an exhaustive review and after years of research, he realized that he was actually looking at traces of rauisuchians, enormous reptiles that reigned before the dinosaurs.
More than ten years ago Apesteguía arrived at the Tunasniyoj and Ruditayoj megafields, accompanied by his colleague Pablo Gallina. At that site, the pair of paleontologists found a paradise for any fossil student; a field full of animal tracks from the past in perfect condition.
At first, Apesteguía and his colleague considered that the footprints belonged to dinosaurs. Because most of the footprints found in the surroundings date back to 70 million years ago, that is, from the Upper Cretaceous. For this reason, it was most likely that their finding was consistent with these data. However, years later the paleontologist returned to the site with more specialized equipment to discover that the footprints were much older than he believed.
Geological and paleoenvironmental studies revealed that the footprints did not belong to dinosaurs, but are much older, dating back to the Triassic period.
“They belong to the middle of the Triassic period, that is, 235 million years ago. Their producers would not have been dinosaurs but the predators that preceded them,” says Apesteguía. “The footprints were left by enormous animals distantly related to modern crocodiles: the rauisuchians.”
The kingdom of the rauisuchians, the reptiles before the dinosaurs
230 million years ago, the Earth looked very different than it does now. All the continents were united into a single landmass called Pangea. On this single supercontinent, dinosaurs were already present, although they were small in size and their evolution was just beginning. Back then and before the dinosaurs ruled the earth, the rauisuchians did.
These were enormous land relatives of crocodiles, ranging in size from 3 to 10 meters long. According to Apesteguía, “they dominated the planet for 80 million years. Between 280 and 200 million years ago.”
Traces of rauisuchians had previously been found in the world, especially in South America. In Argentina, for example, in the Ischigualasto Provincial Park, this type of footprints have been found, as well as those of colossal animals such as saurosuchus galilei or fasolasuchus.
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These enormous reptiles with curved teeth fed on the first herbivorous dinosaurs that walked the Earth. As well as cynodonts, until one day they disappeared. According to Apesteguía, the causes of its extinction are unknown.
“The causes of the extinction of these animals are not well known. “It has not been one of the largest extinctions, but it was important enough to wipe out the main predators in the Jurassic.”
Nor is much known about their populations and habits, which is why this discovery is pure gold for Paleontology. “We still have several questions,” warns Silvina de Valais, co-author of the research. “Did they move in a pack? Did they do migrations? Did they go back and forth to the same places, perhaps year after year? “These are very interesting questions that will guide future work for years.”
References:
Apesteguía, S. Riguetti, Citton, P. Veiga, G. Valais, S. Gabriel, G. The Ruditayoj-Tunasniyoj fossil area (Chuquisaca, Bolivia): a Triassic chirotheriid megatracksite and reinterpretation of purported thyreophoran tracks. Historical Biology. DOI