Sauroniops

Sauroniops Temporal range: Lower Cenomanian, 100 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Holotype specimen, a left frontal bone (MPM 2594)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Family:	†Carcharodontosauridae
Genus:	†Sauroniops Cau et al., 2013[1]
Type species
†Sauroniops pachytholus Cau et al., 2013[1]

Sauroniops is a controversial genus of carnivorous carcharodontosaurid theropod dinosaurs known from the Late Cretaceous (Cenomanian stage) of Morocco. It is known from the Gara Sbaa Formation of the Kem Kem beds and contains a single species, S. pachytholus.

In the early twenty-first century a collector donated a dinosaur frontal bone to the Italian Museo Paleontologico di Montevarchi. He had acquired the specimen from a Moroccan fossil dealer, who again had bought the piece from local fossil hunters near Taouz. Its exact provenance is therefore uncertain. Later research showed that it presented a new species that was in 2012 reported and described by Andrea Cau, Fabio Marco Dalla Vecchia and Matteo Fabbri.^[2]

The next year, 2013, the same authors, formally named the specimen in as the new genus and species Sauroniops pachytholus. The generic name combines "Sauron", a powerful entity from The Lord of the Rings fantasy novel by J.R.R. Tolkien, with the Classical Greek ὄψ, ops, meaning "eye", referencing the Eye of Sauron. The specific name is derived from the Greek παχύς, pachys, meaning "thick", and θόλος, tholos, meaning "dome", in reference to the thick vaulted skull roof unique to this species.^[1]

The holotype, specimen MPM 2594, had probably been recovered from the Gara Sbaa Formation, (originally reported as the Ifezouane Formation, but it is not fossiliferous)^[3] Kem Kem Group, dating to the Lower Cenomanian. It consists of a left frontal bone.^[1]

In 2025, Cau and Paterna described OPH2211, a pair of fused frontals comparable to the holotype of Sauroniops. However, they noted the less robust morphology of the specimen, which they interpreted as possible intraspecific variation, like in other dinosaurs with thickened skulls. The researchers referred the specimen to cf. Sauroniops sp., refraining from assigning it to S. pachytholus.^[4]

A later study in 2020 suggested that Sauroniops was a junior synonym of Carcharodontosaurus saharicus,^[5] though this statement has been criticized by Cau (2020).^[6]

A 2022 study published by Paterna and Cau reevaluated the reasoning of the 2020 study for considering Sauroniops a synonym of Carcharodontosaurus, and found most of the supposed shared features were based on misinterpretations of the Sauroniops holotype. Accordingly, having also found several additional features distinguishing the two taxa, they dismissed the synonymy between Carcharodontosaurus and Sauroniops.^[7]

In 2025, the describers of Tameryraptor remarked on the on the highly fragmentary nature of the Sauroniops holotype, acknowledging the differences between it and Carcharodontosaurus but claiming that taxa should not be named based on such limited material.^[8]

Sauroniops was a large bipedal predator. In their 2013 description, Cau et al. established several unique traits differentiating Sauroniops from its relatives, such as Carcharodontosaurus which is found in the same layers. The nasal bone has an area of contact with the frontal bone over 40% of the latter's length. The frontal has in the left front corner a thick vaulted area. On the front upper rim the frontal has a trapezoid facet to contact the prefrontal, which is no part of the upper rim of the eye socket, and is separated from the facet for the lacrimal bone by a thin vertical ridge. The contact area with the lacrimal is D-shaped, extremely large and has four times the height of the facet with the postorbital bone. On the rear inner side of the frontal an elevated rim is present that is joint to the front vaulted area by a saddle-shaped depression and more towards the front midline of the skull continues in a series of rugosities.^[1]

The frontal has a preserved length of 18.6 centimetres (7.3 in). Near the contact with the lacrimal, the bone is vaulted and extremely thickened to a height of 7.3 centimetres (2.9 in). A second thick area is present at the rear separated from the first by a hollow surface. Such a thickening of the skull roof is more typical of the Abelisauridae. However, in this group it is the postorbital that shows this phenomenon. The similarities to the abelisaurids would then be the result of convergent evolution. The authors explained the thickening as an adaptation for display or to strengthen the skull for intraspecific head-butting.^[1]

The holotype of Sauroniops was originally interpreted as belonging to a basal position in the Carcharodontosauridae, as the sister taxon of Eocarcharia.^[1] A 2025 analysis of large Cretaceous theropods from Africa included Sauroniops and a second specimen potentially referrable to this genus as separte operational taxonomic units (OTUs) in a phylogenetic analysis. These results recovered both OTUs in a clade, diverging after the maxilla referred to Eocarcharia (the type specimen of which having been referred to the Spinosauridae), but before Carcharodontosaurus. These results are displayed in the cladogram below:^[4]