Were dinosaurs WARM-BLOODED?

They were a group of giant reptiles that ruled the oceans at around the same time as Tyrannosaurs rex was terrorising animals on land.

But new research suggests mosasaurs, marine reptiles that grew up to 43ft-long (13 metres), were warm blooded creatures that had body temperatures similar to modern birds.

The work suggests the animals, unlike modern reptiles and fish, were able to maintain their own body temperature, helping to make them the top predators in the oceans at the time.

This may also add to evidence the dinosaurs themselves, which were distantly related to mosasaurs and lived at the same time, were also warm blooded.

Mosasaurs are thought to be most closely related to monitor lizards but died out at the end of the Cretaceous period 66 million years ago in the same event that killed off the dinosaurs.

They were the largest predators in the oceans at the time, with a fearsome array of teeth.

According to Dr Alberto Perez Huerta and his colleagues, these creatures may have had an additional weapon in their arsenal – warm blood.

By analysing oxygen isotopes in mosasaur fossils, the researchers compared them to fossils of cold-blooded fish and turtles from the same period, as well as warm-blooded birds.

The researchers said: ‘The findings of the present study support that mosasaurs were able to maintain a higher internal temperature independent of the ambient seawater temperature.

‘[They] were likely endotherms, with values closer to contemporaneous fossil and modern birds and higher than fish and turtles.

‘Although there are small differences of body temperature among mosasaur genera, these are independent of size and thus inferred body mass.’

This, the researchers added, suggests the body temperature did not appear to change according to the size of the creature – a process known as gigantothermy.

This would have meant the creatures body temperature was determined by the water around them.

While fish and modern marine reptiles like turtles use the water temperature to warm their bodies, this can leave impact the way their muscles and organs function.

Some sharks have evolved circulation that keeps their brains, eyes and muscles above ambient temperatures, helping to increase their ability to detect and react to prey.

If mosasaurs were endothermic, then it would have meant they too could have benefited from sharper senses and reactions.

Dr Perez-Huerta, a geologist, said: ‘there was a paper published in Science in 2010 reporting the thermoregulation in marine reptiles at the time of the dinosaurs focusing on the iconic extinct taxa: ichthyosaurs, plesiosaurs and mosasaurs.

Source: Daily mail

Nada Haj khider