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Yahoo
16-05-2025
- Science
- Yahoo
Mystery of T. Rex's Debated North American Origins Finally Solved
Paleontologists are divided on the origin of one of our favorite dinosaurs, Tyrannosaurus rex. Some say its ancestry is firmly rooted in North America. Others aren't convinced. An international team, led by paleoecologist Cassius Morrison from University College London, now proposes the terrible lizard's 'grandparents' may have instead migrated to North America from Asia across the Bering Strait. "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," Morrison says. "This is in line with past research finding that the T. rex was more closely related to Asian cousins such as the Tarbosaurus than to North American relatives such as Daspletosaurus." In 2024 a scientific team reported that a fossil found in New Mexico, from the T. rex relative Tyrannosaurus mcraeensis, predated its more famous counterpart by around 6 million years. They took this to mean that large-bodied tyrannosaurs had a North American origin. Morrison's team argues this conclusion – and the age estimated for T. mcraeensis – is unreliable, due to the scarcity of specimens and current technological limitations. Their methods for tracing Tyrannosaur family history instead involved modeling based on the fossil record (and its gaps), the dinosaur evolutionary tree and data on the climate and geography of the time. It particularly reveals how tyrannosaurids and megaraptors may have moved across the continents. Based on these models, the team argues that although the T. rex genus likely arose in western North America – or rather the prehistoric continent Laramidia, as the land mass of the time is known – its direct ancestors likely migrated across from Asia. "The genus Tyrannosaurus originated in Laramidia from an ancestrally Asian taxon that emigrated to North America during the Late Campanian – Early Maastrichtian," the authors write. This isn't a new proposition: even the tiniest of T. rex's relatives left fossils that suggest a Beringian land bridge migration. Megaraptors, they found, probably emerged in Asia around 120 million years ago, before dispersing to Europe and the southern 'supercontinent' Gondwana. But no megaraptor fossils have been found in Europe or Africa – at least, not yet. "At the beginning of their evolutionary history, around 120 million years ago, megaraptors were part of a widespread and diverse dinosaur fauna," explains paleontologist Mauro Aranciaga Rolando, from the Bernardino Rivadavia Natural Sciences Argentine Museum. "As the Cretaceous period progressed and the continents that once formed Gondwana began to drift apart, these predators became increasingly specialized. 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." As the world's climate became cooler around 92 million years ago, both megaraptors and tyrannosaurids reached gigantic sizes. But the team found no direct correlation between climate and gigantism in these dinosaurs. Instead, they may have been better adapted to the cold, allowing them to take over the newly vacant apex predator niche in their environments. "They likely grew to such gigantic sizes to replace the equally giant carcharodontosaurid theropods that went extinct about 90 million years ago," says UCL paleontologist Charlie Scherer. "This extinction likely removed the ecological barrier that prevented tyrannosaurs from growing to such sizes." The research is published in Royal Society Open Science. Wild Chimps Appear to Administer 'First Aid' to Each Other Scientists Discover Oldest Reptile Tracks, Rewriting Evolution Timeline Incredible Detail on This Archaeopteryx Fossil Could Help Settle Flight Debate
India Today
09-05-2025
- Science
- India Today
This dinosaur took a land bridge to cross from Asia to North America
The mighty Tyrannosaurus rex may have ruled prehistoric North America, but its roots trace back to Asia, revealed a new say that the T-rex's direct ancestor likely crossed over a land bridge from Asia more than 70 million years ago.'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,' said lead author Cassius Morrison, a PhD student at University College London Earth Sciences. The research, published in Royal Society Open Science, supports earlier findings that T-rex is more closely related to Asian species like Tarbosaurus than to North American ones such as The study used advanced mathematical models to trace how T-rex and its cousins spread around the globe. These models accounted for gaps in the fossil record and included data on climate, geography, and dinosaur family trees.T-rex itself evolved in North America, particularly in Laramidia — the western part of the continent during the Cretaceous period. The study challenged the claims of an earlier paper in 2023 which suggested that Tyrannosaurus mcraeensis, found in New Mexico, predated T-rex by several million years. The new research disputes the dating of that fossil. The researchers suggested that tyrannosaurs may have been able to better exploit cooler temperatures. (Photo: Reuters) advertisementThe team also found that both tyrannosaurids (the group that includes T-rex) and megaraptors, which are its lesser-known relatives, grew rapidly in size during a global cooling period that began 92 million years ago. This happened after the extinction of the carcharodontosaurids, another group of large meat-eating researchers suggest climate change may have helped tyrannosaurs thrive, possibly due to feathers or warm-blooded traits that suited colder are particularly mysterious. Unlike the stocky T-rex, megaraptors had long arms and claws up to 35 cm (14 inches). They likely evolved in Asia 120 million years ago, spreading across Europe and the ancient southern supercontinent Gondwana, which included Africa, South America, and Antarctica.'They likely grew to such gigantic sizes to replace the equally giant carcharodontosaurid theropods that went extinct,' said co-author Charlie Scherer of Aranciaga Rolando, another co-author, added: 'In regions like Asia, megaraptors were eventually replaced by tyrannosaurs. But in places like Australia and Patagonia, they remained apex predators.'
Express Tribune
07-05-2025
- Science
- Express Tribune
Before it ruled North America, T. rex walked from Asia via Land bridge 70 million years ago , study says
Photo: T. rex ancestors likely crossed from Asia to North America via land bridge Listen to article The direct ancestors of Tyrannosaurus rex likely migrated from Asia to North America via a land bridge around 70 million years ago, according to a new study that adds weight to a long-standing paleontologists debate. Researchers led by Cassius Morrison, a doctoral student in palaeontology at University College London (UCL), used mathematical modelling to conclude that the ancestors of T. rex crossed what is now the Bering Strait, between Siberia and Alaska. The findings support earlier research suggesting that T. rex was more closely related to Tarbosaurus, a large Asian carnivore, than to other North American predators such as Daspletosaurus. At the time, the land bridge would have been covered in temperate rainforests, with a climate similar to that of modern-day British Columbia, Morrison told Because apex predators like tyrannosaurids were relatively scarce compared to herbivorous dinosaurs, they were also less likely to be preserved in the fossil record, Morrison explained. To overcome this lack of physical evidence, the team built models incorporating fossil data, family lineage, and environmental conditions. These models allow for gaps in the fossil record and can be revised if new discoveries emerge. The results suggest that fossils of early T. rex relatives may still remain undiscovered in Asia. The study also examined how T. rex and its close relatives grew so large. Researchers found that tyrannosaurids experienced rapid size increases during a period of global cooling. This may have been aided by traits such as warm-bloodedness or feathers, enabling them to thrive in colder climates. Their growth followed the extinction of another group of giant predators— carcharodontosaurids—around 90 million years ago. This created an ecological gap at the top of the food chain. By the end of the Cretaceous Period, T. rex could have weighed up to 9 metric tonnes—comparable to a large African elephant or light tank. Charlie Scherer, a co-author and Earth sciences graduate from UCL, said the findings help explain how the largest tyrannosaurs came to dominate both North and South America. Palaeontologist Steve Brusatte of the University of Edinburgh, who was not involved in the study, praised the work as a detailed examination of how dinosaur evolution aligned with climate shifts. 'It was easier to be big when temperatures were cool,' Brusatte said. 'The kings of the dinosaurs were not predestined to rule, but were helped along by the climate.'
Yahoo
07-05-2025
- Science
- Yahoo
T. rex ancestors crossed from Asia to North America via land bridge 70 million years ago, study finds
Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. The direct ancestor of Tyrannosaurus rex would have arrived in North America after crossing a land bridge from Asia, according to a new study. The report is the latest to weigh in on the fierce debate among paleontologists over the origins of the king of the dinosaurs. A team led by Cassius Morrison, a doctoral student of paleontology at University College London, or UCL, used mathematical modeling to conclude that T. rex precursors likely arrived in North America after crossing the Bering Strait between modern-day Siberia and Alaska around 70 million years ago. The finding tracks with past research that suggests T. rex was more closely related to the large carnivore Tarbosaurus in Asia compared with top predators in North America such as Daspletosaurus, Morrison said in a statement. At the time, the area would have been home to temperate rainforests, with a climate somewhat similar to British Columbia today, Morrison told CNN on Tuesday. T. rex ancestors — tyrannosaurids — would have been fewer in number within their environment compared with the herbivorous dinosaurs they preyed on, much like apex predators such as lions are today, Morrison said. 'And because they are fewer, there are also fewer chances for them to then be preserved in the fossil record,' he said. Faced by this lack of evidence, Morrison and his coauthors instead used mathematical models that incorporate data from the existing fossil record and the T. rex family tree, as well as climatic and environmental conditions, Morrison said. The modeling also accounts for gaps in the fossil record, meaning that it can be updated if new discoveries are made in future research, he added. For example, Morrison said the new study's findings suggest fossils of these T. rex ancestors may still remain undiscovered in Asia. Why T. rex likely evolved into a giant The team also found that tyrannosaurids such as T. rex experienced a rapid increase in size during a period in which global temperatures were falling, suggesting that these dinosaurs were better able to thrive in cooler climates, perhaps thanks to their feathers or the fact that they were more warm-blooded. The rapid growth in size also came after another group of giant meat-eating dinosaurs known as carcharodontosaurids went extinct, leaving 'a vacuum at the top of the food chain,' according to a news release from UCL on Tuesday. This growth meant that, by the time dinosaurs went extinct, T. rex could have weighed as much as 9 metric tons, 'about the same as a very large African elephant or a light tank,' according to the release. Study coauthor Charlie Scherer, a master's graduate in Earth sciences and soon-to-be doctoral student at UCL, said in a statement that the 'findings have shined a light on how the largest tyrannosaurs appeared in North and South America during the Cretaceous (Period) 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,' Scherer said. 'This extinction likely removed the ecological barrier that prevented tyrannosaurs from growing to such sizes.' Steve Brusatte, a paleontologist at the University of Edinburgh in Scotland who was not involved in the study, told CNN that the paper 'is fine scholarly work that forensically tracks tyrannosaurs and other meat-eating dinosaurs over time, and compares their evolution with changes in climate. '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,' he said. 'It was easier to be big when temperatures were cool. The kings of the dinosaurs were not predestined to rule, but were helped along by the climate,' Brusatte added. The study was published in the journal Royal Society Open Science. For more CNN news and newsletters create an account at
