A real life Godzilla that hunted prey on land and in the sea was the most terrifying creature that ever lived, say scientists.
Spinosaurus was a cross between T Rex, a Great White Shark and a crocodile.
It had a paddle-like tail and a bony sail like structure on its back that propelled it through water at incredible speed.
It weighed up to 20 tonnes and reached 50ft in length. Today, only some species of whale are bigger.
Now the most complete skeleton ever found has shed light on the creature’s incredible powers. It ‘rewrites the history of the dinosaurs’.
Some of its bones were first recovered over a decade ago. But the international team has since returned – and excavated its whole tail.
Spinosaurus had no predators even in prehistoric times – and was like something out of a monster movie, according to a study published in the journal Nature.
The remains belonged to a juvenile that lived in North Africa 95 million years ago.
They shows its aquatic skills were remarkable. It had been thought to be a poor swimmer.
Co-author Dr Simone Maganuco, of the Natural History Museum in Milan, Italy, said: ‘The stunning specimen reveals it was indeed very good.
‘This was thanks to its long, flexible and fin-like tail – which it moved from side to side.”
It belonged to the theropods – the group that included T Rex, he told South West News Service.
The amphibious reptile is the only dinosaur that is known to have swum. It had huge jaws packed with six inch long razor sharp teeth.
It was able to walk on soft mud thanks to its large – probably webbed – flat feet.
Dr Maganuco said: ‘Its well-spaced teeth – which are conical rather than blade-like – are better adapted for holding on to slippery prey than for slicing off chunks of meat.
‘Its snout is more similar to that of crocodiles than to other predatory dinosaurs. This housed sensory structures able to capture the waves produced by swimming prey.’
This organ functioned like a sonar – allowing the animal to hunt even in murky waters. Echolocation is used by whales and other marine animals today.
Dr Maganuco said: ‘The nostrils were positioned quite far back – allowing the spinosaur to breathe even when it was poking the tip of its snout in the water.
‘Another important difference with other theropods – including T Rex – is in the structure of its bones.
‘The latter had hollow bones – similar to those of flying birds – whereas the spinosaur’s were dense and compact bones like those of penguins.’
This is adaptation that has occurred in several unrelated animals and aids life in the water by contrasting buoyancy and facilitating submersion, he explained.
The amphibious reptile is the only dinosaur that is known to have swum. It had huge jaws packed with six inch long razor sharp teeth.
Spinosaurus aegyptiacus, described in Nature, belonged to a successful group of huge predatory dinosaurs with a fossil record that spans over 50 million years.
Its exquisitely preserved bones were unearthed at a fossil site in south-eastern Morocco.
Dr Maganuco said: ‘The fossil reveals Spinosaurus had a flexible tail with a unique shape formed by a series of extremely tall neural spines.
‘Modelling suggests the paddle-like tail would have been flexible and able to move laterally to create thrust – propelling the dinosaur in a manner similar to modern crocodiles.’
The idea spinosaurs took to the water is not new but it was thought they were waders that fished from close to shore.
Dr Maganuco said: ‘However, this new evidence of specialised tail-propelled locomotion implies the spinosaurs were aquatic animals that hunted for prey in the water.’
Previously, Spinosaurus was known only from incomplete fossils. This is the best ever found.
Dr Maganuco said: ‘According to our full skeletal reconstruction our individual was a juvenile.
‘It was about 35ft long snout to tail and weighed more than 4 tons. We know on the basis of fragmentary specimens that adults reached 50 ft.
‘They were longer than the famous T-rex, for instance. Adults were bigger than the biggest African elephant. Among living animals, only whales are bigger than Spinosaurus.’
Its fossils have also been found in Egypt, Algeria and Tunisia. Now deserts, 100 million years ago they had massive river systems.
These teemed with fish and other fresh-water animals – ranging from crocodiles to turtles.
Dr Maganuco said: ‘In contrast, the environment in which the spinosaur lived did not contain many prey for it on land.
‘In contrast with other dinosaurs which are predominantly terrestrial animals a long list of anatomical features are indicative of Spinosaurus being adapted to live in water – like crocodiles and hippopotami.’
He said: ‘An adult had no rivals but juvenile spinosaurs may have been prey of giant fish and enormous crocs that lived in the same river systems.
‘They may also have been hunted by other gigantic predatory dinosaurs, such as Carcharodontosaurus, if they ventured on land – like river banks.’
Lead author Dr Nizar Ibrahim, of the University of Detroit Mercy, dubbed Spinosaur’s environment ‘the river of death’ because it was crowded with fierce, huge predators.
Dr Ibrahim says the discovery is the ‘nail in the coffin’ for the idea non-avian dinosaurs never invaded the aquatic realm.
He said: ‘This dinosaur was actively pursuing prey in the water column – not just standing in shallow waters waiting for fish to swim by. It probably spent most of its life in the water.’
Scientists have long opposed the idea they also invaded aquatic habitats. Marine reptiles are not dinosaurs.
Dr Maganuco said: ‘This means we – as a palaeontological community – have to rewrite some chapters of the evolution and the ecology of the dinosaurs – as a group.’
Like many other dinosaurs, Spinosaurus became extinct well before a city-sized asteroid wiped them all out.
Its environment – the North African river system – disappeared during a change in climate.
Sea levels rose and the shorelines moved towards higher ground – cancelling the large deltaic system.
Dr Maganuco added: ‘Spinosaurus was highly specialised for living and feeding in that environment and it became extinct – together with its prey.’
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