Dinosaur as big as a double decker bus is unearthed in Argentina 


A ‘gentle giant’ dinosaur the size of a double decker bus that roamed the planet more than 200 million years ago has been dug up in Argentina.

The discovery winds back the clock on the emergence of giant dinosaurs by a staggering 30 million years – shedding fresh light on their evolution.

Named Ingentia prima meaning ‘great cousin’, the dinosaur was among the first huge sauropods that turned into the largest animals that walked the planet.

Researchers have placed it in a group of early sauropodomorphs called the lessemsaurids – a relative of Diplodocus.

The discovery sheds new light on how Diplodocus, the largest creature to have walked the Earth, evolved to be so massive.

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A dinosaur the size of a double decker bus that roamed the planet more than 200 million years ago has been dug up in Argentina. Pictured is a reconstruction of the Ingentia prima showing an improved avian-like respiratory system with developed cervical air sacs (in green)

A dinosaur the size of a double decker bus that roamed the planet more than 200 million years ago has been dug up in Argentina. Pictured is a reconstruction of the Ingentia prima showing an improved avian-like respiratory system with developed cervical air sacs (in green)

Ingentia Prima was about 33 feet (10 metres) long, 14 feet (4 metres) tall and weighed up to ten tonnes. 

It roamed South America around 210 million years ago during the the Late Triassic.

‘It was enormous. It was at least twice as large as the other herbivores of the time’, said lead researcher Dr Cecilia Apaldetti, a palaeontologist from the National University of San Juan.  

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.  

This speciman changes our understanding of how this group of species became such an immense size.

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‘Until now it was believed the first giants to inhabit the Earth originated during the Jurassic – about 180 million years ago’, said Dr Apaldetti.

‘But with this discovery we can see the first steps toward gigantism occurred 30 million years before the giants dominated practically the entire planet.’

Experts believe this period was a pivotal stage in the history of dinosaurs but the fossil record is very incomplete.

Previously it was believed dinosaurs first appeared around 230 million years ago and took 50 million years to become so large. 

However, this new find shows it happened in less than half that time.

The plant eater, described in Nature Ecology and Evolution, is an ancestor of its titanosaur cousins Brachiosaurus and Diplodocus, renowned for their enormous necks and tails. 

Among the most iconic of dinosaurs, they stretched to 130 feet (40 metres) and weighed up to 80 tonnes (80kg).

Ingentia Prima (pictured) was about 33 feet (10 metres) long, 14 feet (4 metres) tall and weighed up to ten tonnes. The specimen roamed South America around 210 million years ago

Ingentia Prima (pictured) was about 33 feet (10 metres) long, 14 feet (4 metres) tall and weighed up to ten tonnes. The specimen roamed South America around 210 million years ago

WHAT ARE SAUROPODS?

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 

But the earliest examples of this group were small, two-legged creatures. 

To turn into towering beasts, it was believed the development of straight legs for support and continuous, rapid growth were essential. 

Ingentia Prima would have lived in what is now Argentina, but was then the southeast corner of the supercontinent Pangaea. 

Dr Apaldetti said the climate would have been warm, with periodic monsoons. producing an African savanna style landscape, with plenty of shrubs on which Ingentia prima would feed.

Its size would also have put it at less risk of being eaten by the many flesh eating dinosaurs that were already around.

Dr Apaldetti said: ‘Gigantism is an evolutionary survival strategy, especially for herbivorous animals.’

The remains were discovered in a dinosaur 'nest' unearthed at a World Heritage site known for its fossils in Argentina's north western San Juan province

The remains were discovered in a dinosaur ‘nest’ unearthed at a World Heritage site known for its fossils in Argentina’s north western San Juan province

The specimen was found alongside the remains of three individuals belonging to the already known species Lessemsaurus sauropoides.

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They were discovered in a dinosaur ‘nest’ unearthed at a World Heritage site known for its fossils in Argentina’s north western San Juan province.

The remains included shoulder blades, cervical vertebrae and bones from the forelimbs, feet and skull of the four dinosaurs. 

Like their notorious descendants, they also had elongated necks and tails.

They also had the same bird like air sacs – respiratory structures which are thought to have been necessary to keep large animals cool. 

‘This respiratory system is related to the development of air sacs inside their bodies – like modern birds’, said Dr Apaldetti.

‘It allowed them to have large reserves of oxygenated air, and also helped them to keep cool despite being so big.

‘In addition, this kind of breathing implied the presence of cavities, or deep holes, in their bones – known as a pneumatic skeleton – that lightened the weight and would have favoured a large body size.’

But unlike their more recent counterparts they stood on bent legs and had bones that grew thick through accelerated bursts.

The last, iconic sauropods had the benefit of a long history of evolutionary innovation in this regard, said Dr Apaldetti. 

‘Their expansion in the Late Triassic is evident from the appearance of many small, agile two legged types recorded throughout the world’, she said. 

‘Sauropods evolved from these smaller forms and became the largest land animals that ever lived on Earth.’

 





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