Rising levels of oxygen in the atmosphere hundreds of millions of years ago helped dinosaurs in North America to flourish, scientists have found.

Levels of the gas rose by nearly a third in three million years, which experts say is very rapid in geological terms.

Presenting their findings at the Goldschmidt Geochemistry conference in Barcelona, the researchers said this may have set the scene for sauropods and the Chindesaurus to expand into the tropics of North America and elsewhere.

The oxygen rise also coincided with a drop in carbon dioxide.

Scientists tested rocks from the Colorado Plateau and the Newark Basin that formed at the same time about 600 miles apart on Pangaea – what was a “supercontinent” comprising all the modern continents together.

Dinosaur skeletons captured in stunning detail Show all 16 1 /16 Dinosaur skeletons captured in stunning detail Dinosaur skeletons captured in stunning detail Triceratops A ceratopsian, meaning 'horned face', the triceratops lived between 68-66 million years ago in the late Cretaceous period. The pictured skeleton was found in Montana, USA and is on display at the Senckenberg museum in Germany Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Tyrannosaurus rex This large carnivore lived between 68-66 million years ago in the late Cretaceous period. The pictured skeleton, known as Tristan Otto, is on display at the Berlin Museum of Natural History and is one of the best preserved T-rex skeletons in the world. Of the 300 bones that make up the display, 170 are genuine fossils Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Stegosaurus This armoured herbivore lived between 155-145 million years ago in the late Jurassic period. This fossil was found in Bone Cabin Quarry in Wyoming, USA and is on display at the Senckenberg museum in Germany Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Triceratops A ceratopsian, meaning 'horned face', the triceratops lived between 68-66 million years ago in the late Cretaceous period. The pictured skeleton was found in Montana, USA and is on display at the Senckenberg museum in Germany Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Pterodactyl The most well-known of the pterosaurs lived between 150-148 million years ago in the late Jurassic period. The pictured skeleton is the largest ever found and is on display at the Altmuhltal Museum in Germany Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Tyrannosaurus rex This large carnivore lived between 68-66 million years ago in the late Cretaceous period. The pictured skeleton, known as Tristan Otto, is on display at the Berlin Museum of Natural History and is one of the best preserved T-rex skeletons in the world. Of the 300 bones that make up the display, 170 are genuine fossils Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Sabre-toothed tiger Known officially as a smilodon, the sabre-toothed tiger was a dominant predator between 2.5 million - 10,000 years ago in the Pleistocene era. The pictured skeleton is on display at the Senckenberg museum in Germany Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Elaphrosaurus The 'fleet lizard' lived between 154-151 million years ago in the late Jurassic period. This skeleton is on display at the Berlin Museum of Natural History Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Mastodon The American mastodon lived between around 5 million - 10,000 years ago. The pictured skeleton is on display at the Berlin Museum of Natural History Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Gomphotherium This prehistoric elephant lived between 15 and 5 million years ago. The Gomphotherium is remarkably similar to an elephant, with the most obvious difference being the lower tusk that protruded from the bottom jaw of this beast. This particular skeleton is on display at the Senckenberg museum in Germany Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Kentrosaurus This armoured herbivore lived between 155-150 million years ago in the late Jurassic period. The pictured skeleton is on display at the Berlin Museum of Natural History Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Tyrannosaurus rex This large carnivore lived between 68-66 million years ago in the late Cretaceous period. The pictured skeleton, known as Tristan Otto, is on display at the Berlin Museum of Natural History and is one of the best preserved T-rex skeletons in the world. Of the 300 bones that make up the display, 170 are genuine fossils Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Dysalotosaurus This herbivore lived around 152 million years ago in the late Jurassic period. The pictured skeleton is on display at the Berlin Museum of Natural History Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Mantellisaurus This herbivore lived around 152 million years ago in the early Cretaceous period. The pictured skeleton is on display at the Natural History Museum in London Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Stygimoloch It's name meaning 'devil from hell', the stygimoloch lived around 66 million years ago in the late Cretaceous period. The pictured skeleton is on display at the Berlin Museum of Natural History Christian Voigt / SWNS Dinosaur skeletons captured in stunning detail Euoplocephalus This herbivore lived between 76-70 million years ago in the late Cretaceous period. This particular skeleton - on display at the Senckenberg museum in Germany - was found in Alberta, Canada, which is also where the first Euoplocephalus fossil was found in 1897 Christian Voigt / SWNS

They found that oxygen levels in the atmosphere jumped from around 15 per cent to around 19 per cent. Today’s atmosphere has about 21 per cent oxygen.

“We really don’t know what might have caused this increase, but we also see a drop in CO2 levels at that time," said lead researcher, Professor Morgan Schaller of the Rensselaer Polytechnic Institute in New York. "What is remarkable is that right at the oxygen peak we see the first dinosaurs appearing in the North American tropics, the Chindesaurus.

“The sauropods followed soon afterwards.”

He added: “What we can say is that this shows that the changing environment 215 million years ago was right for their evolutionary diversification, but of course oxygen levels may not have been the only factor.”

Chindesaurus was an upright carnivorous dinosaur around 2m long and nearly a metre high. It was found extensively in North America, with origins in the North American Tropics.

Sauropods, which appeared soon after Chindesaurus, were the largest animals ever to live on land.

Professor Mike Benton, of the University of Bristol, said: “The first dinosaurs were quite small, but higher oxygen levels in the atmosphere are often associated with a trend to larger size. This new result is interesting as the timing of oxygen rise and dinosaur appearance is good, although dinosaurs had become abundant in South America rather earlier, about 232 million years ago.”