• T. rex ancestors likely migrated from Asia to North America around 70 million years ago via a land bridge.
• Mathematical modeling, incorporating fossil records and climate data, supports this conclusion.
• Cooler climates may have facilitated the rapid growth in size of tyrannosaurs.

A new study suggests that the direct ancestors of Tyrannosaurus rex migrated from Asia to North America via a land bridge, specifically the Bering Strait area, approximately 70 million years ago. The research, led by Cassius Morrison, used mathematical modeling to analyze fossil records, climate data, and the T. rex family tree. The findings contribute to the ongoing debate about the origins and evolution of the Tyrannosaurus rex and its relatives. The study also indicates that a decrease in global temperatures could be correlated to the increase in size of the species.

• What: The migration of Tyrannosaurus rex ancestors from Asia to North America via a land bridge and the influence of climate on their size.
• Who: Cassius Morrison (doctoral student at UCL), Charlie Scherer (master’s graduate in Earth sciences), Steve Brusatte (paleontologist at the University of Edinburgh), Tyrannosaurus rex ancestors (tyrannosaurids).
• When: Approximately 70 million years ago (migration), Cretaceous Period (appearance in North and South America), about 90 million years ago (extinction of carcharodontosaurid theropods).
• Where: Migration occurred via the Bering Strait between modern-day Siberia and Alaska. Fossils may remain undiscovered in Asia. The study pertains to North and South America.

The study provides valuable insights into the migration patterns and evolutionary pressures that shaped the Tyrannosaurus rex. The use of mathematical modeling to address gaps in the fossil record is a notable aspect of the research. The correlation between global temperature changes and the size of tyrannosaurs suggests that environmental factors played a significant role in their evolution. The extinction of carcharodontosaurids also appears to have created an ecological opportunity for tyrannosaurs to grow to gigantic sizes. The conclusions are supported by expert opinions in the field.

Even the very largest and most dominant dinosaurs were affected by the weather. It seems like tyrannosaurs were able to get big multiple times independently, when cooler climates promoted increases in size.

They likely grew to such gigantic sizes to replace the equally giant carcharodontosaurid theropods that went extinct about 90 million years ago. This extinction likely removed the ecological barrier that prevented tyrannosaurs from growing to such sizes.

The study provides compelling evidence for the migration of T. rex ancestors from Asia to North America and the role of climate in their evolution. The findings highlight the complex interplay between environmental factors, ecological opportunities, and the evolution of apex predators. Future research may uncover additional fossil evidence in Asia, further refining our understanding of the T. rex lineage.