A New Crocodile Species Turns Up in the Rock That Built the Sphinx

Keypoints:

• Researchers named the species Herugavialis cairensis from a skull found in Egypt's Mokattam Formation
• The limestone is about 45 million years old and was used to build the Great Sphinx
• The skull is missing only the tip of its snout
• CT scans showed it differs from the false gharial it was once assigned to
• The study appears in Royal Society Open Science

Fossils from Egypt's Mokattam Formation have revealed a new crocodile species. The skull came from limestone laid down about 45 million years ago in the Eocene epoch. Northern Egypt lay under a warm, shallow sea then. Ancient Egyptians later carved the Great Sphinx from the same rock on the Giza plateau.

The fossils were recovered in the 1920s. Researchers filed them under the living false gharial, Tomistoma schlegelii. An international team used CT scanning to look inside the skull. They found several differences, so the animal became a new species named Herugavialis cairensis.

The name has a story. Philip Mannion of University College London, who co-led the study, noted that the skull lacks the tip of its snout. The Sphinx famously lacks a nose. The team named the animal after the Egyptian god Heru, who may have inspired the monument.

It belonged to the gavials, a crocodile group found today only on the Indian subcontinent and in Southeast Asia. The fossil record shows gavials were nearly global for more than 100 million years. In the Mokattam sea, at least three gavial species lived side by side.

That shows the Mediterranean region once hosted far more crocodile diversity than it does now. The Sphinx stands about 73 metres long and 20 metres high. Today the Nile crocodile is the only crocodile species in Egypt. A monument people know by sight sits on an ancient seafloor, and each block can hold animals no one has named yet.