Paleontologists have long been fascinated with Tyrannosaurus rex‘s evolutionary history. According to a recent University College London (UCL) expert study, T. rex lived in North America. Still, its direct ancestors came from Asia and crossed the Bering Strait on a land bridge around 72 million years ago. Sea level declines during the Late Cretaceous period allowed this migration and established a terrestrial connection between the continents. The research strongly supports the theory that the T-rex origin traced back to Asia before it evolved into the apex predator known today.

The results are consistent with previous research from 2016, which found that T. rex shared more physical characteristics with Asian species like Tarbosaurus than with North American species like Daspletosaurus, according to Cassius Morrison, the study’s primary author. The group used paleoclimate data, evolutionary branches, and fossil sites in a modeling technique. They discovered that the T. rex‘s progenitor most likely lived in Asia and Laramidia, a region now part of western North America. This suggests that there was a migratory event that took place between the Late Campanian and Early Maastrichtian periods.

Climate Change Sparked a Size Surge

The study also examined how the T. rex and its cousins became so big. Researchers found that after a significant change in climate, tyrannosaurids and a similar group called megaraptors, which could grow up to 33 feet in length, grew rapidly. This transition period started following the Cretaceous Thermal Maximum (CTM), which occurred around 92 million years ago and resulted in a notable increase in temperatures worldwide due to elevated greenhouse gas levels brought on by volcanic activity.

Many once-dominant big predators, like the carcharodontosaurids, became extinct as global temperatures fell after the CTM. Tyrannosaurids and megaraptors swiftly seized the ecological openings this extinction produced, allowing them to expand and take control of their surroundings.

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Fossil Distribution and Ancestral Traces

The study emphasized how T. rex fossils were widely distributed throughout Laramidia, supporting the theory that its evolutionary origins were in Asia. According to the modeling, tyrannosaurid fossils’ dates and locations support a theory that their ancestors migrated from Asia to the continent of North America just before the T. rex appeared. These findings add weight to the hypothesis that the T-rex origin traced back to Asia through land migration routes.

Through the integration of fossil data with climatic and evolutionary models, the UCL team tracked the environmental and geographic factors that produced one of the most famous carnivores in prehistory. Their study explains the T. rex‘s beginnings and shows how dinosaur evolution was impacted by prehistoric climatic change.

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