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3mo ago

Study Confirms Asian Origins of T. rex Ancestors via Bering Land Bridge

New research integrates fossil records, evolutionary modeling, and climate data to trace the migration and growth of T. rex ancestors into North America 70 million years ago.

The piece illustrates the disparity of the Northern and Southern hemisphere’s evolution of terrestrial Cretaceous faunas after the Cretaceous Thermal Maximum. On the left, End Cretaceous Southern Hemisphere (Western Gondwana) became dominated by Megaraptorids theropods and titanosaur sauropods. The centre of the piece summaries the extinction event of terrestrial fauna at the Cretaceous Thermal Maximum, where the apex predators the carcharodontosaurids allosaurs went extinct and tyrannosauroids (including megaraptoran and the ancestors of Tyrannosaurus rex) were small. On the right, the end Cretaceous Northern Hemisphere fauna dominated by Tyrannosaurids (such as Tyrannosaurus rex), hadrosaurs and ceratopsian ornithischian dinosaurs. The environment also became more mesic represented by the landscape compared to the more semi-arid seasonal environment earlier in the Cretaceous.

Overview

  • T. rex ancestors migrated from Asia to North America via the Bering land bridge around 70 million years ago, according to a study led by UCL researchers.
  • The study used advanced mathematical models combining fossil evidence, evolutionary trees, and paleoclimatic data to reconstruct this migration and evolutionary history.
  • Global cooling 92 million years ago likely spurred the rapid growth in size of tyrannosaurids, making them better adapted to cooler climates compared to other dinosaur groups.
  • The extinction of carcharodontosaurids 90 million years ago created an ecological opportunity, allowing tyrannosaurids to evolve into dominant apex predators.
  • The research suggests undiscovered fossils of T. rex ancestors may still be located in Asia, offering potential for future discoveries.