A fossil skull roughly 18 inches long, kept for about a century at the State Museum of Natural History in Stuttgart, has been named Herugavialis cairensis, a new genus and species of gavial, in a study in Royal Society Open Science reported on October 7, 2026. The skull comes from the Mokattam Formation near Cairo, the Middle Eocene limestone from which the Great Sphinx was carved. Paul Burke, now at the Swedish Museum of Natural History, led the study, with Philip Mannion of University College London as co-author.
The fossil is a gavial, one of the long-snouted, fish-eating crocodilians, and it is about 45 million years old. Only two gavial species survive today, and both are endangered.
A skull misfiled under Tomistoma for a century
The skull was among fossils collected in the 1920s, and it was first described in a 1927 study by Lorenz Müller, according to UCL’s account of the new work. Müller placed it in the genus Tomistoma, the group that includes today’s false gharial, and the specimen became the type for the name Tomistoma cairense. For nearly a hundred years it stayed there, a nearly complete skull filed under a name that nobody had tested with modern tools.
Micro-CT scanning changed that. Imaging the inside of the skull revealed many differences from the living false gharial, Smithsonian Magazine reported, and measurements of the skull compared against modern and fossil gavials supported the creation of a new genus. UCL’s summary singles out one visible feature, a raised ridge around the eyes. A phylogenetic analysis, described by The Debrief, did not consistently place the animal as a close relative of any Gavialis species, which is part of why Burke concluded that a new genus was warranted.
Press coverage does not reproduce the catalogue number of the specimen or the formal diagnosis, so readers who need those details will have to take them from the paper itself. The skull is also incomplete, since it is missing the tip of its snout.
The Mokattam Formation and its Middle Eocene sea
The Mokattam Formation is a limestone unit in northern Egypt that dates to the Middle Eocene, roughly 45 million years ago. Its rock records shallow marine settings, and The National noted that those waters supported more than one gavial species at the same time. The new animal was therefore one of several long-snouted crocodilians sharing a warm coastline that is now desert and city.
Burke framed the larger pattern in comments carried by UCL: crocodile diversity fluctuated over time, seemingly corresponding to changes in global temperature and sea level. Discover Wildlife quoted him saying that across much of the last 50 million years, the Mediterranean region hosted a high diversity of crocodiles, including gavials. That is a long record for a group now squeezed into the Indian subcontinent and Southeast Asia, and the Egyptian skull adds a branch that had been hidden under the wrong name.
Mokattam limestone and the Great Sphinx
The Sphinx link rests on the rock, not on any record that this particular skull was dug from the monument’s own quarry. Smithsonian Magazine states that the Great Sphinx was carved about 4,500 years ago from limestone of the Mokattam Formation, and UCL describes the new species as found in the same formation the Sphinx was carved from. No source consulted for this article names a specific quarry or ties the skull to a single block of stone.
The coincidences are what made the story travel. The skull lacks the tip of its snout, as the Sphinx lacks its nose, and the authors named the animal after Heru, the Egyptian god also known as Horus, whom they suggest may have inspired the monument. Discover Wildlife, quoting Mannion, said the team chose the name because of this coincidence with the famously missing nose. Those parallels are a naming flourish, though; the scientific content of the paper is the anatomy and the age.
Hesham Sallam of Mansoura University, a co-author according to Smithsonian, tied the animal to Egyptian life more broadly, saying crocodiles were part of the Nile ecosystem, which was central to Egyptian life. The skull predates any human river culture by tens of millions of years, and the Mokattam limestone is the common thread between the animal and the monument.
What a new gavial adds to an endangered family
Living gavials are two species, Tomistoma schlegelii in Indonesia and Malaysia and Gavialis gangeticus, the gharial, in Nepal and northern India. Smithsonian Magazine describes both as endangered, and the fossil record is the only way to see how much larger and more varied the group once was. Gavials have a fossil history of roughly 100 million years, according to The Debrief.
Burke said gavials are critically endangered today but have so much history that few people know about. Naming Herugavialis cairensis puts one more entry in that history, and it came not from a new dig but from re-examining a skull that had already been in a museum drawer since the 1920s.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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