Context:

Tyrannosaurus rex ancestors likely migrated from Asia to North America via a land bridge around 70 million years ago, as per a study led by Cassius Morrison from University College London. Through mathematical modeling, researchers concluded that these ancestors crossed the Bering Strait, and were more closely related to the Asian Tarbosaurus than North American predators. The study posits that T. rex ancestors, called tyrannosaurids, experienced rapid growth in size during a global cooling period, which may have been facilitated by their warm-blooded nature or feathers. This growth occurred after the extinction of carcharodontosaurids, creating a niche for tyrannosaurs to become apex predators. The findings suggest that climate played a significant role in the evolution of large dinosaurs, with cooler temperatures favoring larger body sizes.

Dive Deeper:

• Tyrannosaurus rex ancestors are believed to have migrated from Asia to North America by crossing a land bridge over the Bering Strait around 70 million years ago. This study aligns with previous research suggesting a closer relation to the Asian Tarbosaurus than to North American predators like Daspletosaurus.

• The study utilized mathematical modeling, incorporating fossil data and environmental conditions, to address the scarcity of fossil evidence and gaps in the fossil record. This approach allows for updates if future discoveries are made.

• Tyrannosaurids, the ancestors of T. rex, were fewer in number compared to the herbivorous dinosaurs they preyed on, similar to the dynamic between modern apex predators and their prey. Their scarcity in the fossil record necessitated the use of mathematical models.

• Rapid increase in the size of tyrannosaurids coincided with a period of global cooling, suggesting that these dinosaurs were well-adapted to cooler climates. This adaptation may have been due to being warm-blooded or having feathers.

• The extinction of carcharodontosaurids, another group of large carnivorous dinosaurs, created a vacancy in the top predator role, allowing tyrannosaurids to grow larger and dominate the food chain.

• By the time of the dinosaurs' extinction, T. rex had grown to massive sizes, comparable to an African elephant or a light tank, weighing up to 9 metric tons.

• The study highlights the influence of climate on the evolutionary trajectory of dinosaurs, indicating that cooler temperatures facilitated the independent evolution of large body sizes in tyrannosaurs.