The first dinosaur relatives may have been walking the earth far earlier than was previously thought, research suggested yesterday.
A study of footprints found in Poland from the early Triassic age found they dated from just a few million years after what scientists describe as the greatest mass extinction of all time, the Permo-Triassic mass extinction.
The footprints, thought to be about 250 million years old, are “the indisputably oldest fossils of the dinosaur lineage”, according to the researchers who carried out the study.
The scientists, from Poland, Germany and the US, said the prints, along with those from two other slightly younger sites, provided important insight into the origin and early evolutionary history of dinosaurs.
As well as suggesting that the origin of the animals occurred in the immediate aftermath of the Permo-Triassic event, they indicate that the earliest dinosaur relatives were very small animals.
They had feet only a few centimetres long, walked on four legs and were very rare compared to contemporary reptiles, the findings suggested.
The scientists, Stephen L Brusatte, Grzegorz Niedzwiedzki and Richard J Butler, wrote: “The Polish footprints prompt a substantial extension of early dinosaur history.
“The dinosauromorph lineage originated by at least the Early Olenekian, within a few million years of the devastating Permo-Triassic mass extinction.
“The narrowing gap between the extinction and the oldest stem dinosaurs raises the intriguing possibility that the dinosauromorph radiation may have been part of the general recovery from the PTE, not an unrelated event that occurred 10 to 20 million years later as previously considered.”
The scientists concluded that the dinosaur radiation was a drawn-out affair, “unexplainable by broad platitudes”.
Even in the savage world of dinosaurs, the meek shall inherit the earth, a new discovery suggests. 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.
Newly-discovered dinosaur Sarahsaurus was around 14 feet 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 that each migrated north from their birthplace in what is now South America long after a major extinction event.
No such dinosaurs moved to North America before the disaster at the end of the Triassic Period, one of five great mass extinctions in the Earth’s history.
Study leader Tim Rowe, professor from the University of Texas at Austin, US, 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.”
Sarahsaurus had physical traits usually associated with gigantic animals, including long, straight, pillar-like thigh bones.
Prof. Rowe said he was also intrigued by its hands, which were small but powerful, with large claws.