The Sphinx's secret: Egyptian monument was built from rocks filled with the hidden fossils of ancient crocodiles, scientists discover

The Sphinx is one of ancient Egypt's most enigmatic monuments, and now scientists have found that it could be hiding a very unusual secret.

According to new research, the legendary half-human-half-lion was built from rocks filled with the hidden fossils of ancient crocodiles.

Scientists discovered a new species of extinct crocodile in the 54-million-year-old rocks of the Mokattam Formation in northern Egypt.

This ancient predator has been dubbed Herugavialis cairensis, after the ancient Egyptian god Heru, which the Sphinx is believed to depict.

The fossil crocodile was found in the very same limestone rocks that had been quarried over 4,000 years ago to construct the legendary Great Sphinx of Giza.

And the scientists even think that the Sphinx itself might now contain fossils of these long-extinct crocs.

Lead author Dr Paul Burke, of the Swedish Museum of Natural History, told the Daily Mail: 'It could! It was built from the same rocks where Herugavialis was found, so who knows.

'What I don’t recommend is tearing apart the Sphinx to see if there is!'

According to new research, the Great Sphinx of Giza is built using rocks filled with the fossilised remains of ancient crocodiles 

Scientists discovered a new species of extinct crocodile in the 54-million-year-old rocks of the Mokattam Formation in Egypt that were used to make the Sphinx, naming it Herugavialis cairensis (artist's impression)

Co-author Professor Philip Mannion, of University College London, says: 'Given this coincidence with the famously missing nose of the Great Sphinx, we decided to name the new crocodile after the Egyptian god Heru, who was possibly the inspiration for this iconic monument.'

Herugavialis is a member of the gavial family, a group of crocodiles characterised by their long, thin snouts.

Today, there are only two living species, which are found in freshwater environments across the Indian subcontinent and Southeast Asia.

The fossilised skull of Herugavialis was actually discovered all the way back in the 1920s, during excavations on the Mokattam Formation.

However, scientists initially thought that the skull belonged to the 'false gharial ’, or Tomistoma schlegelii, one of the living species of gavials.

But today, analytical advances in palaeontology, including the use of CT scanning to look inside the skull, have allowed researchers to find key differences between the false gharial and the ancient fossil.

That meant the skull was from an entirely new, previously undiscovered species of extinct crocodile, described in a paper published in Royal Society Open Science. 

And, just like the sphinx is famously missing its nose, the fossilised skull is missing the tip of its snout.

Scientists say that the sphinx itself might contain more fossils of Herugavialis cairensis (artist's impression), but don't recommend taking it apart to find them

Just as the Great Sphinx is famously missing its nose, the fossilised skull of this ancient predator is missing the tip of its snout 

Co-author Professor Philip Mannion, of University College London, says:'Given this coincidence with the famously missing nose of the Great Sphinx, we decided to name the new crocodile after the Egyptian god Heru.'

Even though that part of the fossil is slightly damaged, this distinctive skull shape gives palaeontologists a clue as to how the animal might have once lived.

Dr Burke says: 'Herugavialis has a long, thin snout with razor-sharp, pointed teeth, similar to the extant Indian gharial, Gavialis.

'The Indian gharial feeds primarily on fish, so we think that Herugavialis did the same. In addition, the Mokattam Formation where Herugavialis was recovered from, also preserves plenty of fish fossils, so we assume they fed on these species.'

While the gavials have now vanished from the Mediterranean, the fossil records show that these aquatic hunters once spanned nearly the entire globe for more than 100 million years, with many living in shallow marine habitats.

In fact, scientists think that Herugavialis would have once shared its home with at least two other species of long-snouted gavials.

Dr Paul Burke, of the Swedish Museum of Natural History, says: 'Throughout much of the last 50 million years, the Mediterranean region hosted a high diversity of crocodiles, including gavials.

'However, this diversity fluctuated over time, seemingly corresponding to changes in global temperature and sea level, before the loss of all crocodiles in this region as a result of the drying of the Mediterranean approximately six million years ago.'