During the trias, this elephant-sized mammal parent lived alongside the dinosaurs

"After this discovery, it became clear to us that we were dealing with a giant species," Niedwiedzki told Gizmodo. "We think this is one of the most unexpected fossil discoveries in triassic Europe. Who would have thought that there is a fossil record of a giant mammal cousin the size of an elephant in this part of the world?

Indeed, the discovery of elephantine Lisowicia bojani– a four-legged creature weighing about 9 tons – is rewriting the history of evolution. The dinosaurs, according to this new study, are not the only big animals to marvel in the Triassic landscape.

To be clear, dicynodonts were not real mammals. As Niedwiedzki has explained, these are extinct non-mammalian therapies, a group of synapsids including mammals and their ancestors (the synapsids are sometimes called proto-mammals or rod-like mammals). Dicynodonts are a sister line of the mammalian lineage, but they are not our direct ancestors. They are more like our distant cousins, much like monkeys are distant cousins ​​of humans.

Fossils of dicynodonts have been found in Africa, Asia, and North and South America. They tend to be smaller in size, about the size of larger dogs, and their sprawling forelegs that come out of the side, similar to lizards. But the fossil dicynodon discovered in Poland is different: it is larger and suggests a creature standing on all fours.

"I heard about these bones for the first time a decade ago, while I was working in Poland, looking for dinosaurs with Tomasz and Grzegorz," Steve Brusatte told Gizmodo , a paleontologist from the University of Edinburgh not directly involved in the study. "They teased me with glimpses of these new giant bones that they had discovered, so much bigger than anything anyone had ever found in Triassic rocks. Since then, I'm waiting for the publication of the newspaper and it was cruel to make me wait so long! But it was worth the wait, because it is simply one of the most surprising fossil discoveries of recent years. "

According to Brusatte, what is remarkable in this new discovery is that this very old cousin of mammals had developed similar characteristics – an enormous size and columnar members held under the body – as would be true mammals, although several tens of millions of years later.

"Before these giant bones were discovered, you would have been considered insane if you had ever suggested that elephant-sized giant mammal cousins ​​lived alongside some of the earliest dinosaurs," said Brusatte. "We used to think that after the end of the Permian's extinction [252 million years ago]when about 90-95% of all species disappeared, mammals and their parents withdrew in the shadows as dinosaurs rose to enormous heights. This is the story I tell my students during my lectures. But this new discovery throws a key in this simple story. "

Lisowicia bojani appeared around the same time that the long-necked dinosaurs were developing a gigantic body – but these dicynodonts reached sizes that the mammals themselves would not reach before 150 million years ago.

Careful analysis of the Lisowicia bojani The fossil suggests that he was 2.6 meters tall and 4.5 meters long. Its weight, at 18,000 pounds, is a little heavier than modern elephants.

Fossils found next to the dicynodont, such as plants, amphibians, dinosaurs and other first relatives of mammals, suggest that they lived next to gymnosperm-like plants and that they eventually consumed them. brachyphyllum and a fern seed called Lepidoptera. Its landscape was a relatively flat shore with sparse vegetation. The researchers also found traces of a dinosaur much like those of North America. Coélophyse– a predatory dinosaur two meters long (six feet). As for the main predator of this world, this distinction belongs to Smok, a carnivore with two legs, 6 meters long (20 feet) whose name means dragon in Polish.

"But the most exciting discovery for me," said Niedwiedzki, "is the remains of our direct cousins ​​- small and similar [proto-mammals]who lived under the feet of these gigantic dicynodontes. "

Clearly, the conditions were met during the Upper Triassic for Lisowicia bojani to emerge, but as to why he disappeared, while great dinosaurs still lived, now represents a deep mystery.

"The dinosaurs have won, the dicynodonts have disappeared and tiny synapsids – primitive mammals – have long lived in the shadow of the dinosaurs during the Jurassic and Cretaceous," said Niedwiedzki. Before the extinction of the dinosaurs, however, these animals "showed what they should become," he added.

Lisowicia bojani have not emerged or disappeared overnight, other fossils, younger and older, are therefore likely to be discovered. In addition, researchers do not know if the new specimen is fully developed, so the discovery of new specimens would help clarify the situation.

"The mammalian lineage has had its own interesting history during the Triassic period," said Brusatte. "They were diverse, successful and dominant animals, living alongside the early dinosaurs. The Triassic was not just the time of the rise of the dinosaurs, and who knows what new surprises about the fossils might be coming, especially in Poland, where many new discoveries are being made. "