Way of the dinosaur was patience not power
A dwarf dinosaur that lived 190 million years ago challenges the view that the "terrible lizards" conquered the world by overpowering their rivals.
Instead it is more likely they simply stepped into the space left by departing competitors, say researchers.
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Hide AdNewly-discovered dinosaur Sarahsaurus was around 14ft long and weighed about 250lb.
It may seem big by modern standards, but the four-footed plant-eater was a small ancestor of giant sauropods such as diplodocus – the largest land animals that ever lived.
Evidence from Sarahsaurus and two other similar "sauropodomorphs" indicates each migrated north from their birthplace in what is now South America.
However, no such dinosaurs moved to North America before the disaster at the end of the Triassic Period, one of five mass extinctions in the Earth's history.
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Hide AdStudy leader Professor Tim Rowe, from the University of Texas at Austin, said: "We used to think of dinosaurs as fierce creatures that outcompeted everyone else. Now we're starting to see that's not really the case.
"They were humbler, more opportunistic creatures. They didn't invade the neighbourhood. They waited for the residents to leave and when no one was watching, they moved in." The research is reported in Proceedings Of The Royal Society.