doi.org/10.1098/rsos.242238
Credibility: 989
#T.Rex
The famous dinosaur Tyrannosaurus rex (T rex) evolved in North America, but its ancestors came from Asia, crossing an ancient land bridge that connected the two continents more than 70 million years ago.
That’s the conclusion of a new study led by researchers at University College London (UCL) and published in the journal Royal Society Open Science.
The study also found that the tyrannosaurid group, which includes T.rex, and another group called megaraptors, grew significantly in size during a period of global cooling following a spike in heat 92 million years ago.
These dinosaurs may have been better adapted to colder climates, possibly by having feathers or a body more similar to that of warm-blooded animals.
How did T.rex get to North America?
The study involved scientists from universities including Oxford, Pittsburgh, Aberdeen, Arizona, Anglia Ruskin, Oklahoma and Wyoming.
They used mathematical models based on fossils, dinosaur evolutionary trees and information about the climate and geography of the time.
These models even took into account gaps in the fossil record, that is, where we have not yet found fossils.
Cassius Morrison, a PhD student at UCL and lead author of the study, explains: “There is a great deal of debate about where the ancestor of T.rex came from.
Some palaeontologists thought it was North America, others thought it was Asia.
Our models suggest that the ‘grandparents’ of T.rex came from Asia, crossing the Bering Strait between Siberia (now Russia) and Alaska.”
He adds that T.rex is more closely related to Asian dinosaurs, such as Tarbosaurus, than to North American relatives, such as Daspletosaurus.
Although many T.rex fossils have been found in North America, fossils of its direct ancestors may still be hidden in Asia.
The researchers concluded that T.rex itself evolved in North America, specifically in a region called Laramidia, which was the western part of the continent at the time.
They also disagreed with a previous study that suggested that a relative of T.rex, called Tyrannosaurus mcraeensis, found in New Mexico, was older than T.rex.
They say the dating of this fossil is unreliable.
The mysterious megaraptors
Megaraptors are lesser-known carnivorous dinosaurs, as few fossils of them have been found.
Unlike T.rex, which had a powerful bite, they had thinner heads, long arms (the size of a person) and huge claws, up to 35 cm long.
The study suggests that megaraptors emerged in Asia about 120 million years ago and spread to Europe and then to the supercontinent Gondwana, which included present-day Africa, South America and Antarctica.
This means that they lived in places like Europe and Africa, where their fossils have not yet been found.
Why did they get so big?
Both tyrannosaurids and megaraptors grew in size at the same time, during a period of global cooling after the so-called Cretaceous Thermal Maximum, 92 million years ago.
This growth occurred after the extinction of other giant carnivorous dinosaurs, the carcharodontosaurids, which left a “void” at the top of the food chain.
Researchers believe that tyrannosaurs (both tyrannosaurids and megaraptors) took advantage of the colder temperatures to thrive, unlike other dinosaurs.
At the end of the age of dinosaurs, T.rex could weigh up to 9 tons (like a very large African elephant or a light tank), while megaraptors reached 10 meters in length.
Different adaptations
Megaraptors evolved large claws for hunting, while T.rex used its powerful bite.
This may have happened because they hunted different prey.
In North America, T.rex hunted dinosaurs such as Triceratops and Ankylosaurus.
In the south, in Gondwana, megaraptors probably hunted the young of sauropods, long-necked dinosaurs.
Charlie Scherer, co-author of the study and founder of the UCL Palaeontological Society, explains: “Our findings show how the largest tyrannosaurs appeared in North and South America during the Cretaceous and why they grew so large.
They replaced other giant carnivorous dinosaurs that went extinct around 90 million years ago.”
Co-author Mauro Aranciaga Rolando, from the Bernardino Rivadavia Museum of Natural Sciences in Argentina, says: “Early in their history, 120 million years ago, megaraptors were part of a diverse fauna.
Over time, as the continents of Gondwana broke apart, they became more specialised, dominating their ecosystems as top predators in places like Australia and Patagonia.”
This study helps us understand how T.rex and its relatives spread across the world and became the giants we know today.
Published in 05/27/2025 15h47
Text adapted by AI (Grok) and translated via Google API in the English version. Images from public image libraries or credits in the caption. Information about DOI, author and institution can be found in the body of the article.
Reference article:
Original study:
| Geoprocessing Drone Systems HPC |
| ERP and CRM Systems Mobile Systems AI |