His lineage came from Asia and took advantage of a global extinction to become the largest predator on the planet

For decades, the lineage of Tyrannosaurus rex – the most iconic predator of the Cretaceous period – has been a reason for heated debate among paleontologists. Did he be born in Asia and emigrated to North America? Or did it originate in American soil? Now, a new biogeographic modeling study and climatic evolution, led by researchers from institutions such as the University College London and the Argentine Museum of Natural Sciences, sheds light on this enigma and changes what we thought we knew about the origin of the origin of the T. rex and of their giant cousins, the enigmatic megagoaptors.

A trip of more than 70 million years

Research reveals that the closest ancestors of the T. rex They probably crossed from Asia to North America about 70 million years agotaking advantage of a land bridge that linked Siberia with Alaska. Although the T. rex As a species it evolved later in Laramidia —A dough of land that comprised the current western coast of North America – its “grandparents” were Asian immigrants.

This finding not only confirms connections with Asian species such as Tarbosaurusbut we question recent discoveries in North America that suggested a local origin for the T. rex. Through complex mathematical models that integrate known fossils, evolutionary trees and climate data of the Cretaceous, the team rebuilt migratory routes and diversification processes that explain the lineage of the most famous predator on the planet.

Lethal claws and colossal bodies: the other lineage branch

But the T. rex He did not walk only towards the domain of the Cretaceous. Together with him, a parallel branch of theore -called megagapting dinosaurs reached equally impressive dimensions, although with a very different anatomy. With narrower skulls, disproportionately long arms and curved claws of up to 35 centimeters, the megaraptors were formidable predators that conquered the southern hemisphere.

Despite their kinship with the tyrannosaurus, the megagraptors seem to have followed a different evolutionary story. According to the study, these animals emerged in Asia about 120 million years ago and dispersed to Europe, Africa and finally the Gondwana Supercontinent, establishing themselves in what are today South America, Australia and, possibly, Antarctica. This more cosmopolitan distribution is consistent with the hypothesis that they would have been dominant predators in regions where the tyrannosaurus failed to impose themselves.

The crucial role of climate and extinction

One of the most revealing aspects of the study is the link between the climatic changes of the Cretaceous and the evolution of Gigantism in these species. About 92 million years ago, the Earth experienced an event known as the thermal maximum of the Cretaceous, with oceanic temperatures that reached 35 ° C in the tropics. This stage was followed by a global decrease in temperatures, which coincided with the extinction of other great predators such as Carcharodontosáuridos.

This emptiness at the top of the food chain would have favored the tyrannosaurs and megagaptors, allowing them to occupy the role of superdedors and grow up to colossal sizes. He T. rex He weighs up to 9 tons, while some megagraptors reached 10 meters in length, comparable with modern light tanks.

Adaptation to colder climates, possibly facilitated by feathers or a physiology closer to that of mammals, could have been a key evolutionary advantage for these groups. Unlike other less thermally efficient dinosaurs, tyrannosaurus and megagaptors prospered while the planet cooled.

Although the T. rex He has been the subject of popular and scientific attention for decades, the megagaaptors are still an enigma. Their fossils are fragmentary and scarce, especially in regions such as Europe or Africa, where it is suspected that they also inhabited. However, recent findings in Argentina and Australia have begun to fill the gaps of this story.

In particular, it has been proposed that the megaraptors of the southern hemisphere evolved more specialized as the continents of Gondwana were fragmented. This geographical pressure, together with the absence of direct competence with other great thermals, allowed them to become the dominant predators of their ecosystems.

This new interdisciplinary approach allows to rebuild a much more dynamic and complex story of the evolution of predatory dinosaurs. Not only tells us about transcontinental migrations and anatomical transformations, but also of the determining role played by environmental and ecological factors in the evolutionary history of the Mesozoic giants.

In addition, the study raises a call to look towards Asia with more attention. According to the authors, the fossils of the direct ancestor of the T. rex They could still be buried in unexplored regions of that continent, hoping to change our vision of the most famous lineage of the animal kingdom again.

The last word is in fossils

Like everything in Paleontology, the conclusions of this work are open to review with future findings. The fascinating thing is that, despite having advanced modeling techniques and a growing fossil record, there are still huge lagoons to fill. Each new fossil, each bone fragment, can alter what we think we know about these prehistoric beasts.

In the case of T. rex And his megagarpting relatives, what emerges today is a story of migrations, adaptations to climate and ecological competition. A story that shows that even the greatest did not reach the top by simple destination, but thanks to a complex dance between evolution, environment and opportunity.