The hyperlink misplaced within the evolution of ‘Tyrannosaurus rex’ lived in Mongolia tens of millions of years in the past | Science | EUROtoday

For tens of millions of years, eutiranosaurios, amongst which the imposing Tyrannosaurus rexdominated the ecosystems of Asia and North America as supercarders. Although it’s suspected that this species descended from smaller ancestors, the scarcity of intermediate fossils has maintained that chapter of evolution in a relentless unknown.

Now, a brand new gentle has begun to light up that prehistoric previous so distant for people. Two partial skeletons present in Mongolia between 1972 and 1973 by the native paleontologist Altangerel Perley and relegated for years to the silence of the scientific archives, have been re -defeated by the Jared Voris workforce and giving it Zelenitsky of the University of Calgary (Canada). The results of the evaluation, which is printed within the journal Naturenot solely revives curiosity in these fossils, but it surely offers its title to a brand new species and gender of tyrannosauroid, the Glue Mongolivesis.

During a go to to the Institute of Paleontology, of the Mongolian Academy of Sciences, whereas investigating different species reminiscent of Tarbosourus and Alioramus, the workers confirmed Jared Voris a drawer with a fossil initially described in 1977 as Alectrosaurus olseni. When analyzing it, the scientist realized that it was not that species, however a very new one. This was how they recognized and appointed the stays discovered within the Bayan Shireh formation, identified for his or her ample dinosaurs fossils and different organisms of the higher Cretaceous. “It turned out to be the immediate ancestor of the great tyrannourids, such as the Tyrannosaurus rex. We are talking about the great carnivorous, bipedal dinosaurs, with huge skulls and sharp teeth, ”explains Zelenitsky to El País.

The phylogenetic research of those stays – of the evolutionary growth of a species – means that KhankhuulUU It occupied a vital place within the evolutionary tree of the tyrannourids. Its anatomical traits are intermediate, which makes it an evolutionary bridge and hyperlink misplaced within the historical past of this group, whose dispersion patterns date again to the top of the Cretaceous, a geological interval that features the final a part of the period of dinosaurs. “It is essentially the last divergent member of a group that led the great tyranosáurids,” provides the scientist, who has been 32 years as a paleontology professor.

The species was a detailed relative of the Eutyrannosauria and a possible predecessor of the sturdy Tyrannosaurini, as probably the most sleek Alioraminicharacterised by having smaller snouts. Scientists estimate that KhankhuulUU It weighed about 750 kg. This is bigger than their ancestors, which weighed round 200 kg, however smaller than their descendants, a few of which weigh greater than a ton.

The most important problem was to find out which anatomical traits have been related to determine evolutionary relationships, along with appropriately differentiating between youth and grownup specimens. “This discovery led us to reassess the entire family tree. He clarified how and why these dinosaurs evolved to becoming great predators, and helped solve a confusion that had long existed in this field,” he says.

How did the migration of dinosaurs developed?

This species emphasizes the authors, might symbolize an evolutionary turning level, marked by migration. The first main occasion of such a KhankhuulUU (or a really shut species) from Asia to North America, it was about 86 million years in the past, by way of the Northern Terrestrial Bridge. That species gave rise to the primary nice tyrannourids In North America.

“Then, about 78–79 million years ago, one of those American tyrannosaurs returned to Asia. That population was divided into two lineages,” explains the paleontologist Jared Voris. One that advanced in the direction of smaller, virtually youthful types, and one other that advanced in the direction of massive and sturdy predators who dominated as “aparty predators.”

Thus, a kind of Asian large tyrannosaurs crossed once more to North America, about 67-68 million years in the past. That lineage gave rise to T. rex, that ultimately extinguished after the impression of an asteroid, about 66 million years in the past. The authors of the analysis consider that there are nonetheless empty within the fossil registry of the tyrannosaurs, in order that they see extra area work within the areas might assist fill them.

“We are working on a similar project, although we are not yet ready to talk about it publicly,” says Mongoris. An attention-grabbing analysis line is to check the primary tyrannosauroids, species that existed earlier than the looks of KhankhuulUU. These early types are much less preserved and have been much less studied than the good tyrannourids, so there may be nonetheless a lot to find. “That would allow us to try our evolutionary hypothesis and better understand when and where these animals lived,” concludes Voris.