This is an accepted version of this page Ceratosaurs are members of the clade Ceratosauria, a group of dinosaurs defined as all theropods sharing a more recent common ancestor with Ceratosaurus than with birds.

Ceratosauria includes three major clades: Ceratosauridae, Noasauridae, and Abelisauridae, found primarily (though not exclusively) in the Southern Hemisphere.

Originally, Ceratosauria included the above dinosaurs plus the Late Triassic to Early Jurassic Coelophysoidea and Dilophosauridae, implying a much earlier divergence of ceratosaurs from other theropods.

Ceratosaurs are generally moderately large in size, with some exceptions like the larger Carnotaurus and the significantly smaller noasaurs.

The major defining characteristics of Ceratosauria include a robust skull with increased ornamentation or height and a shortening of the arms.

Since C. nasicornis was the only other dinosaur discovered at the time to share this trait, Marsh concluded that Ceratosauria must be placed very near Archaeopteryx and its related groups.

In fact, the scientific community's most common interaction with Ceratosauria throughout much of the 20th century was the disputation of its existence, performed by the likes of Romer, Lapparent, Lavocat, Colbert, and Charig amongst others.

Many scientists, such as Carrano and Sampson, have postulated the lack of specimens is due to a poor fossil record, rather than an indictment on the abundance of ceratosaurs at the time.

[12] By the Cretaceous period, abelisauroids had apparently become extinct in Asia and North America, possibly due to competition from tyrannosauroids.

However, advanced abelisauroids of the family Abelisauridae persisted in the southern continents until the Cretaceous–Paleogene extinction event 66 million years ago.

Noasaurids were also nimble and lightly built, with feet showing adaptations for running such as a long central foot bone.

[16] The origin of Ceratosauria could have been in Northern Pangea where Saltriovenator, its close relative Berberosaurus, and Carmelopodus footprints have been found.

[17] †Herrerasauridae †Eoraptor †Eodromaeus †Daemonosaurus †Tawa †Coelophysoidea †Dilophosauridae †Ceratosauria †Megalosauroidea †Allosauroidea Coelurosauria The following cladogram shows the internal relationships within Ceratosauria following an analysis by Diego Pol and Oliver W. M. Rauhut, 2012.

[18] This was later expanded on in a 2018 paper on ceratosaur paleobiology, which named a new clade Etrigansauria, which contained the families Abelisauridae and Ceratosauridae.

Spinostropheus Elaphrosaurus Limusaurus Deltadromeus Laevisuchus Noasaurus Masiakasaurus Berberosaurus Eoabelisaurus Genyodectes Ceratosaurus Chenanisaurus Abelisaurus Ilokelesia Arcovenator Indosaurus Majungasaurus Rajasaurus Dahalokely Rahiolisaurus Ekrixinatosaurus Skorpiovenator Viavenator Pycnonemosaurus Quilmesaurus Carnotaurus Aucasaurus Similar results were shown by the phylogenetic analysis from the describers of Alpkarakush in 2024, where noasaurids were recovered outside a polytomy of ceratosaurids and abelisaurids.

[22] These shared features, along with the fact that Abelisauridae seem to have replaced Carcharodontosauridae in South America, has led to suggestions that the two groups were related.

Noasaurids were considered to be distinctive abelisauroids with a peculiar "sickle claw" on the second toe of the foot, convergently developed with that of deinonychosaurians.

[2] Whether correlation or causation, it has been largely observed that late Cretaceous ceratosaurs were found less in areas dominated by basal tetanurans (Africa) or coelurosaurs (North America and Asia).

[29] On the other hand, other groups of paleontologists have found that the bite of Carnotaurus was relatively powerful, and more adept at hunting and wounding large prey.

[31] Studies of Majungasaurus indicate that it was a much slower-growing dinosaur than other theropods, taking nearly 20 years to reach adult size.

Noasaurines are Late Cretaceous noasaurids known exclusively from southern continents and islands such as South America, Madagascar, and India.

In North America, it is likely that members of the family such as C. nasicornis competed with allosaurids (A. fragilis) for food, such as sauropods common to the region at the time.

The presence of C. nasicornis at the Cleveland-Lloyd Dinosaur Quarry along with the remains of several allosaurids is a good indication of just how close members of this family and other predators coexisted.

Abelisauridae thrived during the Cretaceous period on the ancient southern supercontinent of Gondwana, and today their fossil remains are found on the modern continents of Africa and South America, as well as on the Indian subcontinent and the island of Madagascar.

The specimens provide new information on abelisauroids, which are still poorly known in the Brazilian fossil record, and on the distribution of this group of theropod dinosaurs in South America.