Argentinian researchers discover an extraordinary 220 million year old animal cemetery in San Juan

It is a surprising accumulation of fossils that would belong to dinosaurs, giant crocodiles and mammalian ancestors. In this "bed of bones", there are skulls and dismembered parts of, at least, seven or eight individuals, although there could be many more.

The fossilised dinosaur remains discovered in western Argentina are believed
to be 220 million years old [Credit: CTyS-UNLaM Agency]

Dr. Ricardo Martínez, a researcher at the Institute and Museum of Natural Sciences of the University of San Juan (IMCN), highlighted the CTyS-UNLaM Agency that “it is a mass of almost bone against bone, there are no sediments; it is as if they had made a well and filled it with bones”.

In 2014, IMCN investigators had also released another bonebed, but that accumulation was not at all comparable to the one announced today. “This is something impressive; it's as if, here, the carnivores had a well and were pulling the bones after the meal”, joked the paleontologist.

In times of re-releases of Pet Sematary, this finding is an increased remastering of the bed of bones found years ago in Balde de Leyes, which is another very important site located southeast of the province of San Juan. If you want, too, with an even more terrifying image.

Dr. Martinez compared: “What we find now is a true accumulation of bones, glued together, with skulls, jaws, of at least 10 different animals totally disarticulated, piled bone on bone”.

Scientists speculate the site was a former drinking hole at a time of great drought,
where the creatures died of weakness [Credit: CTyS-UNLaM Agency]

The diameter of this bone bed is King size, about two meters. Meanwhile, the depth may be much greater than that of a sommier. “So far, we have managed to dig about 50 centimeters and it continue down, so it could have a depth of a meter or two, we do not know, but, with what we have seen so far, it is already impressive", pondered the chief of the IMCN paleontology area. He added: "In addition, we verify that the diameter of the accumulation grows as we move forward with the excavation”.

Dr. Cecilia Apaldetti, researcher at IMCN and CONICET, explained that the finding was made in September of last year and, now, after the summer season in which there are no campaigns because of the high temperatures and the rains, they have returned with the intention to extract the entire block.

"However, this accumulation of bones is bigger than we thought, we still can not find the base and we will return to the site in these weeks with more people and more logistics, to be able to extract the entire block, for which we must make a concrete base and, of course, we will need a crane and adequate machinery to be able to achieve it”, Apaldetti told the CTyS-UNLaM Agency.

Beyond the fact that the famous Ischigualasto basin in San Juan always surprises, researchers claim never to have seen anything like it. "It is very difficult to find a cause to this tremendous accumulation of bones”, remarked Martinez, who directs this research.

Scientists preparing the fossil bed for transporation
[Credit: CTyS-UNLaM Agency]

The expert noted that, beyond the extraordinary that is this accumulation, the finding has an even greater scientific value, "because these bones belong to a time interval that is among the fauna of Los Colorados, in which there was a great abundance of herbivorous dinosaurs especially sauropodomorphs and, below, is the Ischigualasto formation that has the most primitive and ancient dinosaurs known in the world”.

But in this interval that would be about 220 million years old, many species were not known and here a lot of individuals have been found, at least seven or eight, although there may be many more.

Among these new species, there would be discinodes -predecessors of mammals the size of an ox- and other archosaurs that, surely, are unknown species that can be dinosaurs and the giant ancestors of crocodiles, for example.

The researchers run a hypothesis about the factors that would have allowed this surprising accumulation of bones worthy of the imagination of a Stephen King of the Triassic. "Our theory is that it could have been a time of great drought and there was a body of water, a small lake for example, in which the herbivores were piled up to drink and, as the water evaporated, they were weakening and they were dying in the place”.

Once dead, other animals trampled their bodies and also appeared predators that partially disintegrated their bones. "Many of the predators also died on the spot, either because of the scarcity of water or because this site became a kind of trap for them”, Martínez said. He added: "This is how we thought that this great accumulation of bones would have taken place that we do not yet know the depth and the extension that it has; We will know this as we move forward with the investigation”.

Source: CTyS-UNLaM Agency [April 18, 2019]