Ceratosuchops

Ceratosuchops Temporal range: Barremian,
Holotype skull fragments
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Family:	†Spinosauridae
Clade:	†Ceratosuchopsini
Genus:	†Ceratosuchops Barker et al., 2021
Type species
†Ceratosuchops inferodios Barker et al., 2021

Ceratosuchops (meaning "horned crocodile face") is a genus of spinosaurid from the Early Cretaceous (Barremian) of Britain.

Discovery and naming

Known material of Ceratosuchops (rear) and Riparovenator (front) diagrams by Dan Folkes

The holotype remains of this taxon consist of IWCMS 2014.95.5 (premaxillary bodies), IWCMS 2021.30 (a posterior premaxilla fragment), and IWCMS 2014.95.1-3 (a nearly complete braincase). These, in addition to a referred right postorbital (IWCMS 2014.95.4), were recovered from rocks in Chilton Chine of the Wessex Formation.

In 2021, Ceratosuchops inferodios was named and described by a team of paleontologists including Chris Barker, Darren Naish, David Hone and others. The specific name means "hell heron", in reference to the ecology presumed by the research team.

Classification

In their phylogenetic analysis, Barker et al. (2021) recovered Ceratosuchops within the Baryonychinae, as the sister taxon to the coeval Riparovenator. They are, in turn, in a clade containing Suchomimus, which they name Ceratosuchopsini.

Baryonychinae	ML1190 (=Iberospinus) Baryonyx Ceratosuchopsini Suchomimus Riparovenator Ceratosuchops

In 2023, Sereno and colleagues tentatively combined Ceratosuchops and Riparovenator into a single taxonomic unit for their phylogenetic analysis. They reason that the different features between the two taxa could be attributed to individual variation, citing the cranial variation present in specimens of Allosaurus fragilis. Some of their supposed distinguishing features are also seen in parts of the braincase of Suchomimus, their closest relative. The results of their phylogenetic analysis (with Ceratosuchops and Riparovenator scored together) yielded similar results to those of Barker et al. (2021), with the Wessex baryonychine fossils recovered as the sister taxon to Suchomimus.

Spinosauridae	Camarillasaurus Baryonychinae Baryonyx Ceratosuchopsini Ceratosuchops (+Riparovenator) Suchomimus Spinosaurinae Ichthyovenator Vallibonavenatrix Spinosaurus Irritator

Palaeobiology

CT scan 3D models of the braincase of Ceratosuchops and Baryonyx (left), and 3D endocast of the brain of Ceratosuchops (right)

A 2023 study by Barker and colleagues based on CT scans of the braincases of Ceratosuchops and Baryonyx found that the brain anatomy of these baryonychines was similar to that of other non-maniraptoriform theropods. Their neurosensory capabilities such as hearing and olfaction (sense of smell) were unexceptional, and their gaze stabilisation less developed than those of spinosaurines, so their behavioural adaptations were probably comparable to those of other large-bodied terrestrial theropods. This suggests that their transition from terrestrial hypercarnivores to semi-aquatic “generalists” during their evolution did not require substantial modification of their brain and sensory systems. This could mean that spinosaurids were either pre-adapted for detection and capture of aquatic prey, or that their transition to semi-aquatic lifestyles only required modifications to the bones associated with the mouth. Their reptile encephalization quotient values imply that the cognitive capacity and behavioural sophistication of baryonychines did not deviate much from that of other basal theropods.

Palaeoenvironment

Life restoration

Ceratosuchops lived in a dry mediterranean habitat in the Wessex Formation, where rivers were home to riparian zones. Like most spinosaurs, it would have fed on available small to medium-sized aquatic and terrestrial prey in these areas.

Other dinosaurs from the Wessex Formation of the Isle of Wight include the theropods Riparovenator, Neovenator, Eotyrannus, Aristosuchus, Thecocoelurus, Calamospondylus, and Ornithodesmus, the ornithopods Iguanodon, Hypsilophodon, and Valdosaurus, the sauropods Ornithopsis, Eucamerotus, and Chondrosteosaurus, and the ankylosaur Polacanthus. Barker and colleagues stated in 2021 that the identification of the two additional spinosaurids from the Wealden Supergroup, Riparovenator and Ceratosuchops, has implications for potential ecological separation within Spinosauridae if these and Baryonyx were contemporary and interacted. They cautioned that it is possible the Upper Weald Clay and Wessex Formations and the spinosaurids known from them were separated in time and distance.

It is generally thought that large predators occur with small taxonomic diversity in any area due to ecological demands, yet many Mesozoic assemblages include two or more sympatric theropods that were comparable in size and morphology, and this also appears to have been the case for spinosaurids. Barker and colleagues suggested that high diversity within Spinosauridae in a given area may have been the result of environmental circumstances benefiting their niche. While it has been generally assumed that only identifiable anatomical traits related to resource partitioning allowed for coexistence of large theropods, Barker and colleagues noted that this does not preclude that similar and closely related taxa could coexist and overlap in ecological requirements. Possible niche partitioning could be in time (seasonal or daily), in space (between habitats in the same ecosystems), or depending on conditions, and they could also have been separated by their choice of habitat within their regions (which may have ranged in climate).