"Ceratosaurs" is the catchword for a group of small to large theropods with primitive four-fingered hands, strange skulls (some with a kinked snout) and pelves with fused elements. Overall, ceratosaurs form a group having developed from small, 1m animals in the Late Triassic or Early Jurassic, such as Procompsognathus, Segisaurus, or Coelophysis, and then developing into ever larger forms, some nearing gigantic proportions, such as Dilophosaurus (all specimens of which may have been juvenile or subadult at nearly 20ft!) or Carnotaurus, a 30ft monstrosity. Recent evidence suggests they may be paraphyletic, however, the term "ceratosaur" will forever be used to characterize these animals, from coelophyids to abelisaurids. (see Rowe, 1990; Bonaparte et al., 1990.)

+--Abelisauria
   +--Noasauridae
      |  |--Liagbueino
      |  +--Noasaurus
      +--Abelisauroidea
         +--+--Xenotarsosaurus
            +--+--Elaphrosaurus
               +--Abelisauridae
                  |--+--Majungasaurus crenatissimus
                  |--Carnotaurinae
                  |  |--Carnotaurus sastrei
                  |  |--Indosaurus matleyi
                  |  +--Majungatholus atopus
                  +--Abelisaurinae
                     |--Abelisaurus comahuensis
                     +--Indosuchus

Abelisaurids are odd taxa with fully fused ankles (having the proximal tarsals fused to the tibia and fibula, and the distal tarsal fused to the metatarsals, forming a tibiotarsus and tarsometatarsus, repspectively) unusually short arms, skulls with postorbitals and lachrymals touching above the orbit, a process of the postorbital pointing forward below the eye and almost touching the lachrymal, a very large external mandibular fenestra with loose contact between the dentary and post-dentary bones, very small or absent neural spines on the cervical vertbrae, and a few other details. The most striking example of the abelisaurids is Carnotaurus from Argentina (below), a carnotaurine taxon with a very short skull and two large processes of the frontals projecting over the eyes, giving it the appearance of a bull, hence the name. Similar taxa, such as Indosaurus from India, have robust frontal processes that may be the bases of horn or bosses, and Majungatholus from Madagascar, with fused frontals forming a single upright "horn" or boss. Abelisaurines have longer skulls without any apparent ornamentation as in Carnotaurus, like Abelisaurus, a giant form that may have reached 35ft or more, and Indosuchus, a recently redescribed form with an intermediate skull.



Carnotaurus sastrei -- Bonaparte, 1986

The Coelophysoidea, comprised of the Segisauridae sensu Sereno (1999) [Procompsognathus and Segisaurus] and the Coelophysidae [Coelophysis, Dilophosaurus, and their allies], are small to fairly large animals built on, compared to most other theropods, rather conservative and generalized lines. Their heads are large, on long necks, with long tails, but with short legs are shorter arms, and long dorsa, with fairly derived pelves being fused together, but with pubes that are broad and turned downward steadily along their length. Coelophysoids, with the possible exception of segisaurids sensu Sereno, have a distinct diastema or notch between premaxilla and maxilla without a companion feature to explain its prescence or function. Cranial ornamentation is also elaborated, though to less a variety as in abelisaurs, but distinctive nonetheless, as in Dilophosaurus.


The Coelophysidae, from the top: Coelophysis bauri,
Syntarsus rhodesiensis, Syntarsus kayentakatae,
Liliensternus liliensterni, and Dilophosaurus wetherilli.

Liliensternus is known from vary incomplete cranial remains, but may have supported cranial ornamentation as in S. kayentakatae and D. wetherilli. A second species od Dilophosaurus, D. sinensis, may or may not pertain to Dilophosaurus, and I have not seen material to restore it. Other coelophysoids are not known by cranial material or the material is too broken or fragmentary to suggest a restoration: Eocoelophysis, Camposaurus, Segisaurus, Procompsognathus, or Gojirasaurus.

NOTE: Padian and Sampson (1999) and Novas (1998) have suggested that Ceratosauria is polyphyletic, and so this page will feature a perspective on this issue in the future and will reflect the suggestion futher.

Not prepared yet -- please have patience.

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