EarthSky’s Deborah Byrd spoke with paleontologist Cass Morrison on Monday, May 12, about his new study showing that ancestors of T. rex came from Asia. He said they entered North America by crossing the Bering Strait into what’s now Alaska. And Deborah and Cass talked about a lot more besides, from dinosaur feathers to the incredibly long span of time that dinosaurs lived on Earth. It was fun! Watch in the player above, or on YouTube.
No hype. Just real science, powered by real people. That’s you.
- A new study suggests confirmation of a long debate, about whether Tyrannosaurus rex or T. rex had ancestors that migrated from Asia via a land bridge. The study suggests the answer is yes.
- We know that megaraptors did originate in Asia around 120 million years ago and spread globally, becoming apex predators in regions like Patagonia and Australia.
- The study also points to Tyrannosaurid and megaraptor large body sizes due to their ability to adapt to a cooling climate and the extinction of other top predators.
Tyrannosaurids and megaraptors were two types of carnivorous dinosaurs that lived during the Cretaceous Period, 143 to 66 million years ago. T. rex is perhaps the most famous example of a Tyrannosaurid, and the best-known North American dinosaur. It lived during a 2-million-year period, 68 to 66 million years ago. Recently, scientists used advanced mathematical modeling to trace the evolutionary paths of these dinosaurs. The researchers confirmed that the ancestors of T. rex crossed into North America from Asia via a land bridge connecting the continents.
We know that T. rex was a huge creature and a fearsome predator. In their analysis, these researchers also found that both Tyrannosaurids and megaraptors attained large body sizes. The researchers said this happened as they adapted to a cooling climate, following a temperature spike some 92 million years ago. Also, as other predatory dinosaurs became extinct, the Tyrannosaurids and megaraptors had higher prey availability.
All in all, the study paints a fascinating history of dinosaur species evolving over a period of perhaps 150 million years.
These findings were published in Royal Society Open Science on May 7, 2025.
New study sheds light on T. rex origins
So the new study suggests that T. rex ancestors arrived from Asia over 70 million years ago, crossing a land bridge to enter western North America. The scientists also said that T. rex evolved in western North America, attaining a massive size during a time when the climate was cooling. This indicated that T. rex might have been warm blooded or might even had feathers for insulation. It’s possible that young T. rexes had feathers, which they then lost as they aged.
Cassius Morrison, the study’s lead author, said:
The geographic origin of T. rex is the subject of fierce debate. Paleontologists have been divided over whether its ancestor came from Asia or North America.
Our modelling suggests the ‘grandparents’ of T. rex likely came to North America from Asia, crossing the Bering Strait between what is now Siberia and Alaska.
This is in line with past research findings that the T. rex was more closely related to Asian cousins such as the Tarbosaurus than to North American relatives such as Daspletosaurus.
Dozens of T. rex fossils have been unearthed in North America, but our findings indicate that the fossils of T. rex’s direct ancestor may lie undiscovered still in Asia.
Mathematical models trace the origins of tyrannosaurid and megaraptor dinosaurs
Tyrannosaurids and megaraptors were both apex predators of the Cretaceous. Scientists think they diverged into separate evolutionary paths about 170 to 165 million years ago, long before T. rex came on the scene.
In this study, the researchers traced these dinosaurs’ evolutionary tracks across continents of the Cretaceous Period (143 to 66 million years ago). They ran advanced mathematical models using data on fossils from across the world. They also utilized dinosaur evolutionary trees, as well as information about the climate and geology of that time.
Their analysis revealed that megaraptors were more widespread across the globe than previously thought. These dinosaurs likely emerged in Asia about 120 million years ago. Then, they spread to Europe and to Gondwana, a large southern continent that includes present-day Africa, Antarctica, and South America.
For tyrannosaurids, the models supported previous research that said the ancestors of T. rex were present in both Asia and western North America. This indicated that T. rex’s ancestors originated in Asia. And they crossed into western North America across a land bridge connecting the two continents. Therefore, according to this study, T. rex most likely evolved in western North America.
Influence of climate, environment and geology on evolution
The study also showed how changes in climate, environment and geology shaped the evolution of tyrannosaurids and megaraptors.
About 92 million years ago, there was a peak in global climate temperatures known as the Cretaceous Thermal Maximum. As the planet cooled, tyrannosaurids and megaraptors evolved larger body sizes. For instance, about 66 million years ago, before all dinosaurs became extinct, T. rex weighed up to 10 US tons (9,000 kg). And megaraptors were up to 33 feet (10 meters) in length.
The scientists think that both dinosaur groups were able to grow so large in size because they could better adapt to a cooling planet. In addition, other large carnivorous dinosaurs, the carcharodontosaurids, became extinct as the climate cooled, providing an opening at the top of the food chain for tyrannosaurids and megaraptors.
Tyrannosaurid and megaraptor dinosaurs evolved large body sizes
Charlie Scherer, a paper co-author, commented on the size gain in T. rex:
Our findings have shined a light on how the largest tyrannosaurs appeared in North and South America during the Cretaceous and how and why they grew so large by the end of the age of dinosaurs.
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.
Another paper co-author, Mauro Aranciaga Rolando, added his insights into the megaraptors:
At the beginning of their evolutionary history, around 120 million years ago, megaraptors were part of a widespread and diverse dinosaur fauna.
As the Cretaceous period progressed and the continents that once formed Gondwana began to drift apart, these predators became increasingly specialized. This evolutionary shift led them to inhabit more specific environments.
While in regions like Asia megaraptors were eventually replaced by tyrannosaurs, in areas such as Australia and Patagonia they evolved to become apex predators, dominating their ecosystems.
Bottom line: A new study explains how tyrannosaurid and megaraptor dinosaurs attained large sizes, and that the ancestor of T. rex originated in Asia.
Source: Rise of the king: Gondwanan origins and evolution of megaraptoran dinosaurs
Read more: Rare juvenile T. rex discovered by young fossil hunters
The post Here’s how fierce T. rex got to North America first appeared on EarthSky.
from EarthSky https://ift.tt/TREOBGP
EarthSky’s Deborah Byrd spoke with paleontologist Cass Morrison on Monday, May 12, about his new study showing that ancestors of T. rex came from Asia. He said they entered North America by crossing the Bering Strait into what’s now Alaska. And Deborah and Cass talked about a lot more besides, from dinosaur feathers to the incredibly long span of time that dinosaurs lived on Earth. It was fun! Watch in the player above, or on YouTube.
No hype. Just real science, powered by real people. That’s you.
- A new study suggests confirmation of a long debate, about whether Tyrannosaurus rex or T. rex had ancestors that migrated from Asia via a land bridge. The study suggests the answer is yes.
- We know that megaraptors did originate in Asia around 120 million years ago and spread globally, becoming apex predators in regions like Patagonia and Australia.
- The study also points to Tyrannosaurid and megaraptor large body sizes due to their ability to adapt to a cooling climate and the extinction of other top predators.
Tyrannosaurids and megaraptors were two types of carnivorous dinosaurs that lived during the Cretaceous Period, 143 to 66 million years ago. T. rex is perhaps the most famous example of a Tyrannosaurid, and the best-known North American dinosaur. It lived during a 2-million-year period, 68 to 66 million years ago. Recently, scientists used advanced mathematical modeling to trace the evolutionary paths of these dinosaurs. The researchers confirmed that the ancestors of T. rex crossed into North America from Asia via a land bridge connecting the continents.
We know that T. rex was a huge creature and a fearsome predator. In their analysis, these researchers also found that both Tyrannosaurids and megaraptors attained large body sizes. The researchers said this happened as they adapted to a cooling climate, following a temperature spike some 92 million years ago. Also, as other predatory dinosaurs became extinct, the Tyrannosaurids and megaraptors had higher prey availability.
All in all, the study paints a fascinating history of dinosaur species evolving over a period of perhaps 150 million years.
These findings were published in Royal Society Open Science on May 7, 2025.
New study sheds light on T. rex origins
So the new study suggests that T. rex ancestors arrived from Asia over 70 million years ago, crossing a land bridge to enter western North America. The scientists also said that T. rex evolved in western North America, attaining a massive size during a time when the climate was cooling. This indicated that T. rex might have been warm blooded or might even had feathers for insulation. It’s possible that young T. rexes had feathers, which they then lost as they aged.
Cassius Morrison, the study’s lead author, said:
The geographic origin of T. rex is the subject of fierce debate. Paleontologists have been divided over whether its ancestor came from Asia or North America.
Our modelling suggests the ‘grandparents’ of T. rex likely came to North America from Asia, crossing the Bering Strait between what is now Siberia and Alaska.
This is in line with past research findings that the T. rex was more closely related to Asian cousins such as the Tarbosaurus than to North American relatives such as Daspletosaurus.
Dozens of T. rex fossils have been unearthed in North America, but our findings indicate that the fossils of T. rex’s direct ancestor may lie undiscovered still in Asia.
Mathematical models trace the origins of tyrannosaurid and megaraptor dinosaurs
Tyrannosaurids and megaraptors were both apex predators of the Cretaceous. Scientists think they diverged into separate evolutionary paths about 170 to 165 million years ago, long before T. rex came on the scene.
In this study, the researchers traced these dinosaurs’ evolutionary tracks across continents of the Cretaceous Period (143 to 66 million years ago). They ran advanced mathematical models using data on fossils from across the world. They also utilized dinosaur evolutionary trees, as well as information about the climate and geology of that time.
Their analysis revealed that megaraptors were more widespread across the globe than previously thought. These dinosaurs likely emerged in Asia about 120 million years ago. Then, they spread to Europe and to Gondwana, a large southern continent that includes present-day Africa, Antarctica, and South America.
For tyrannosaurids, the models supported previous research that said the ancestors of T. rex were present in both Asia and western North America. This indicated that T. rex’s ancestors originated in Asia. And they crossed into western North America across a land bridge connecting the two continents. Therefore, according to this study, T. rex most likely evolved in western North America.
Influence of climate, environment and geology on evolution
The study also showed how changes in climate, environment and geology shaped the evolution of tyrannosaurids and megaraptors.
About 92 million years ago, there was a peak in global climate temperatures known as the Cretaceous Thermal Maximum. As the planet cooled, tyrannosaurids and megaraptors evolved larger body sizes. For instance, about 66 million years ago, before all dinosaurs became extinct, T. rex weighed up to 10 US tons (9,000 kg). And megaraptors were up to 33 feet (10 meters) in length.
The scientists think that both dinosaur groups were able to grow so large in size because they could better adapt to a cooling planet. In addition, other large carnivorous dinosaurs, the carcharodontosaurids, became extinct as the climate cooled, providing an opening at the top of the food chain for tyrannosaurids and megaraptors.
Tyrannosaurid and megaraptor dinosaurs evolved large body sizes
Charlie Scherer, a paper co-author, commented on the size gain in T. rex:
Our findings have shined a light on how the largest tyrannosaurs appeared in North and South America during the Cretaceous and how and why they grew so large by the end of the age of dinosaurs.
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.
Another paper co-author, Mauro Aranciaga Rolando, added his insights into the megaraptors:
At the beginning of their evolutionary history, around 120 million years ago, megaraptors were part of a widespread and diverse dinosaur fauna.
As the Cretaceous period progressed and the continents that once formed Gondwana began to drift apart, these predators became increasingly specialized. This evolutionary shift led them to inhabit more specific environments.
While in regions like Asia megaraptors were eventually replaced by tyrannosaurs, in areas such as Australia and Patagonia they evolved to become apex predators, dominating their ecosystems.
Bottom line: A new study explains how tyrannosaurid and megaraptor dinosaurs attained large sizes, and that the ancestor of T. rex originated in Asia.
Source: Rise of the king: Gondwanan origins and evolution of megaraptoran dinosaurs
Read more: Rare juvenile T. rex discovered by young fossil hunters
The post Here’s how fierce T. rex got to North America first appeared on EarthSky.
from EarthSky https://ift.tt/TREOBGP
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