Triops Longicaudatus
Triops Longicaudatus Red
Triops Longicaudatus
Triops Longicaudatus Red
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A giant on the move: New insights into the origins of Tyrannosaurus rex
It is the big star among the dinosaurs: Tyrannosaurus rex, icon of prehistoric times and favourite of pop culture and palaeontology alike. Hardly any other dinosaur has been depicted, analysed and discussed so often. But although its enormous teeth, tiny arms and imposing size are well documented, there are still unanswered questions about its origins.
New research results
North America was long regarded as the place of origin of T. rex – numerous fossils have been found there, particularly in the US states of Montana and South Dakota as well as in the Canadian province of Alberta. These regions once belonged to the primeval continent of Laramidia, which extended over large parts of North America in the late Cretaceous period. The enormous body size of the T. rex – up to twelve metres long and four metres high – also seemed to fit in with this geological landscape.
However, new research findings are focussing on Asia as the region of origin. A study by University College London concludes that the direct ancestors of T. rex came from Asia – and travelled to North America via a land bridge.
The team led by palaeontologist Cassius Morrison analysed fossil finds, family trees of various tyrannosaur species and climatic developments of past geological eras. The result: a migration across the Bering Strait around 72 million years ago is probable. The king of the dinosaurs first developed in North America, but its evolutionary roots lie in present-day Asia.
‘Our modelling shows that the ancestors of T. rex probably migrated to North America from Siberia via Alaska,’ says Morrison. This hypothesis is supported by genetic relationships with Asian species such as Tarbosaurus, while North American tyrannosaurs such as Daspletosaurus are more distantly related.
In addition to the origin, the study also sheds light on the rapid increase in size of the genus. The so-called Cretaceous Thermal Maximum – a phase of intense global warming around 92 million years ago – was apparently responsible for this. Volcanic eruptions and tectonic activity drove up the CO₂ content of the atmosphere, and tropical seas reached temperatures of up to 35 degrees. Under these conditions, many dinosaur species grew to gigantic dimensions within a short period of time.
When the climate cooled down again, the ecological niches also changed. Large carnivores such as the carcharodontosaurids disappeared – and made way for the up-and-coming tyrannosaurids, including the T. rex.
‘He epitomises the image of the American dinosaur. Strong, scary, dominant,’ says co-author Steve Brusatte from the University of Edinburgh. ‘But in reality, he was a migrant – an immigrant from Asia.’
The study not only provides new insights into the evolution of the world’s most famous predatory dinosaur – it also shows the extent to which the Earth’s history was shaped by global dynamics, migratory movements and climatic upheavals.
