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Ceratosauria Marsh, 1884 sensu Gauthier 1984

Ceratosauria Skeleton (reconstructed)

The common ancestor of Coelophysis and Ceratosaurus and all its descendants. Autapomorphies which underwrite holophyly of Ceratosauria include:

a)Two pairs of pleurocoels in the cervicals

b)Transverse processes on the dorsal vertebrae are strongly backturned, and triangular in dorsal aspect.

c)The pubic plate is perforated by a large pubic fenestra ventral to the obturator foramen.

d)The sacrum is completely fused, and the sacral ribs are fused to the ilium.

e)The pelvic girdle is fused.

f)Trochanteric shelf present on the lesser trochanter of the femur of robust individuals.

g)A sulcus is present on the base of the crista tibiofibularis.

h)Distal tarsals II and III are fused to their respective metatarsals during late ontogeny, yielding a tarsometatarsus.

Ceratosauria is among the most fascinating and enigmatic of theropod clades, if for no other reason than their astonishing similarities (in some regards) to ornithurine birds. Holophyly of Ceratosauria has been questioned by several researchers, see Rauhut (1998), Carrano & Sampson (1999), Britt et al (2000) and Paul (2002). While these studies raise valid points, it is the opinion of the author that the characters underwriting ceratosaur holophyly remain compelling.

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