Sauropods liked it HOT! Long-necked dinosaurs were restricted to warmer regions of Earth - suggesting they were close to being 'cold-blooded' like modern-day reptiles, study finds

  • Sauropods were close to being 'cold-blooded' like modern-day reptiles — study
  • Research shows they preferred to live in warmer, more tropical regions on Earth
  • Diplodocus and Brontosaurus avoided any temperatures approaching freezing
  • May have had unique in-between physiology compared to other dinosaur types

Giant, long-necked sauropods preferred to live in warmer, more tropical regions on Earth, suggesting they may have had a different physiology from other dinosaurs, a new study has found.

Species such as Diplodocus and Brontosaurus appear to have avoided freezing temperatures, researchers said, meaning they could have been more 'cold-blooded' like modern-day reptiles.

The study looked at fossil records of three main dinosaur types: sauropods, theropods – which include velociraptors and Tyrannosaurus rex – and ornithischians such as the Triceratops.

Combining this with data about the climate throughout the Mesozoic era, which lasted from around 230 to 66 million years ago, along with information about how continents have moved across the globe, researchers concluded that sauropods were restricted to warmer, drier habitats than other dinosaurs. 

These habitats were likely to be open, semi-arid landscapes, similar to today's savannahs. 

Sauropods (such as the Brontosaurus shown) preferred to live in warmer regions on Earth, suggesting they may have had a different physiology from other dinosaurs, a study has found

Sauropods (such as the Brontosaurus shown) preferred to live in warmer regions on Earth, suggesting they may have had a different physiology from other dinosaurs, a study has found

SAUROPODS: LONG NECKED AND SMALL BRAINED DINOSAURS 

Sauropods were the first successful group of herbivorous dinosaurs, dominating most terrestrial ecosystems for more than 140 million years, from the Late Triassic to Late Cretaceous. 

They had long necks and tails and relatively small skulls and brains.

They stretched to 130 feet (40 metres) and weighed up to 80 tonnes (80,000kg) — 14 times the weight of an African elephant.

They were widespread — their remains have been found on all the continents except Antarctica.  

They had nostrils high up on their skulls — rather than being located at the end of the snout like those of so many other terrestrial vertebrates. 

Some fossils shows that these nostril openings were so far up the skull that there were very close to the eye openings. 

Sauropods such as the Diplodocus began to diversify in the Middle Jurassic about 180 million years ago. 

Source: University of California Museum of Paleontology 

Advertisement

The study, which was led by experts at University College London (UCL) and the University of Vigo, wanted to investigate the enigma of why sauropod fossils are only found at lower latitudes, while fossils of other main dinosaur types seem to be everywhere, with many located in the polar regions. 

'Our research shows that some parts of the planet always seemed to be too cold for sauropods,' said co-author Dr Philip Mannion, of UCL's Earth Sciences department.

'They seem to have avoided any temperatures approaching freezing. 

'Other dinosaur types, in contrast, could thrive in Earth's polar regions, from innermost Antarctica to polar Alaska — which, due to the warmer climate, were ice-free, with lush vegetation.

'This suggests sauropods had different thermal requirements from other dinosaurs, relying more on their external environment to heat their bodies — slightly closer to being 'cold-blooded', like modern-day reptiles. 

'Their grand size hints that this physiology may have been unique.'

The fossil records showed no examples of sauropods above a latitude of 50 degrees north – an area encompassing most of Canada, Russia, northern Europe and the UK – or below 65 degrees south, making up Antarctica.

In contrast, there are rich records for theropods and ornithischians living above 50 degrees north in later periods from 145 million years ago.

To test if this was a true reflection of where sauropods lived, researchers used a statistical technique to adjust for gaps in the fossil record, and also analysed where the highest diversities of dinosaur types were in different periods throughout the Mesozoic era. 

While in the past it was believed that dinosaurs were cold-blooded, relying on the external environment to heat their bodies, it is now thought they were closer to warm-blooded mammals, generating some of their own body heat.

However, the study authors said sauropods, which were among the largest land animals ever to have existed, may have had a unique in-between physiology, closer to being cold-blooded than other dinosaur types.

First author Dr Alfio Alessandro Chiarenza, formerly of UCL who is now based at the University of Vigo, Spain, said: 'It may be that sauropods were physiologically incapable of thriving in colder regions, or that they thrived less well in these areas than their dinosaurian cousins and were outcompeted.

This image shows the latitudinally more restricted distribution of sauropod dinosaurs (white) compared to other dinosaurs (in black)

This image shows the latitudinally more restricted distribution of sauropod dinosaurs (white) compared to other dinosaurs (in black)

Species such as Diplodocus (shown) and Brontosaurus likely avoided freezing temperatures, researchers said, meaning they could have been more 'cold-blooded' like modern-day reptiles

Species such as Diplodocus (shown) and Brontosaurus likely avoided freezing temperatures, researchers said, meaning they could have been more 'cold-blooded' like modern-day reptiles

'A mix of features may have helped sauropods shed heat more easily than mammals do today. 

'Their long necks and tails would have given them a larger surface area, and they may have had a respiratory system more akin to birds, which is much more efficient.

'Some species of theropods and ornithischians are known to have had feathers or downy fur helping them retain body warmth.

'This suggests they may have generated their own body heat. For sauropods, however, there is no evidence of this kind of insulation.'

He added: 'Sauropods' strategies for keeping their eggs warm may also have differed from the other dinosaurs. 

'Theropods probably warmed eggs by sitting on them, whereas ornithischians seem to have used heat generated by decaying plants. 

'Sauropods, meanwhile, may have buried their eggs, relying on heat from the sun and the ground.' 

The study has been published in the journal Current Biology.

KILLING OFF THE DINOSAURS: HOW A CITY-SIZED ASTEROID WIPED OUT 75 PER CENT OF ALL ANIMAL AND PLANT SPECIES

Around 66 million years ago non-avian dinosaurs were wiped out and more than half the world's species were obliterated.

This mass extinction paved the way for the rise of mammals and the appearance of humans.

The Chicxulub asteroid is often cited as a potential cause of the Cretaceous-Paleogene extinction event.

The asteroid slammed into a shallow sea in what is now the Gulf of Mexico.

The collision released a huge dust and soot cloud that triggered global climate change, wiping out 75 per cent of all animal and plant species.

Researchers claim that the soot necessary for such a global catastrophe could only have come from a direct impact on rocks in shallow water around Mexico, which are especially rich in hydrocarbons.

Within 10 hours of the impact, a massive tsunami waved ripped through the Gulf coast, experts believe.

Around 66 million years ago non-avian dinosaurs were wiped out and more than half the world's species were obliterated. The Chicxulub asteroid is often cited as a potential cause of the Cretaceous-Paleogene extinction event (stock image)

Around 66 million years ago non-avian dinosaurs were wiped out and more than half the world's species were obliterated. The Chicxulub asteroid is often cited as a potential cause of the Cretaceous-Paleogene extinction event (stock image)

This caused earthquakes and landslides in areas as far as Argentina. 

While investigating the event researchers found small particles of rock and other debris that was shot into the air when the asteroid crashed.

Called spherules, these small particles covered the planet with a thick layer of soot.

Experts explain that losing the light from the sun caused a complete collapse in the aquatic system.

This is because the phytoplankton base of almost all aquatic food chains would have been eliminated.

It's believed that the more than 180 million years of evolution that brought the world to the Cretaceous point was destroyed in less than the lifetime of a Tyrannosaurus rex, which is about 20 to 30 years.

The comments below have not been moderated.

The views expressed in the contents above are those of our users and do not necessarily reflect the views of MailOnline.

We are no longer accepting comments on this article.