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RE: Genera belonging to Herrerasauridae



Evangelos Giakoumatos wrote-

The most recent publication I have access to, TDE, Supplement 3 (Glut, 2003), indicates that Herrerasauridae is compirised of ?Agnostiphys, Caseosaurus, Chindesaurus, Herrerasaurus, ?Spondylosoma, and Staurikosaurus.

How consistent is this account with current thinking? Should any of these be excluded, or any other genera added?

The definition of Herrerasauridae is actually (Herrerasaurus + Staurikosaurus), so both Herrerasaurus and Staurikosaurus must be herrerasaurids. This is agreed on by almost everyone, with one of the few dissenters being Kischlat (2001), who found Staurikosaurus to be a basal sauropodomorph. However, the study this conclusion was based on is not yet published. It is probably related to Kischlat and Barbarena's (1999) statement Staurikosaurus is only distantly related to Herrerasaurus, due in part to the lack of a trochanteric shelf. If Staurikosaurus is a sauropodomorph, Herrerasauridae becomes the same as Saurischia or Eusaurischia (depending on where you place Herrerasaurus), and would probably be redefined.


Langer (2004) found Agnostiphys to resemble eusaurischians in the elongate postacetabular process, but to be outside Neotheropoda due to the semiperforate acetabulum and short preacetabular process. In addition, the astragalus has a deep elliptical slot for the tibial descending process, which is seen in Herrerasaurus and basal sauropodomorphs. So it's more likely a eusaurischian, not a herrerasaurid.

Conveniently, I just wrote the Chindesaurus entry for my website (though it is not uploaded yet)-
Sereno (1999) found Chindesaurus to be the sister taxon of Staurikosaurus within Herrerasauridae, while Langer (2004) notes it has characters congruent with being a non-herrerasaurid herrerasaurian. Rauhut (2000) found it difficult to assign Chindesaurus to a less inclusive taxon than Dinosauriformes, though he agrees with Langer that the dorsals are less shortened than herrerasaurids. Furthermore, he finds the medially expanded brevis shelf resembles crurotarsans more than it does the laterally expanded brevis shelf of most dinosaurs. He believes the holotype may pertain to multiple individuals and/or taxa. Though originally a paratype of Chindesaurus, Hunt et al. (1998) made UMMP 8870 the holotype of a new taxon - Caseosaurus. This was based on the shallow brevis shelf, a more ventrally placed medial longitudinal ridge and a transversely thinner postacetabular blade. Langer (2004) has synonymized the taxa without comment.


Spondylosoma was reassigned to Crurotarsi by Galton (2000), though Langer (2004) noted the sacral rib character used was also found in herrerasaurids, and that another sacral rib character is more similar to the latter than to crurotarsans. However, the deltopectoral crest is shorter than in dinosaurs. So its placement seems uncertain, with either teratosaurid or herrerasaurid assignment being possible.

Other possible herrerasaurids include "Comanchesaurus", "Revueltoraptor" and other undescribed and unnamed specimens.

Taxa which have been referred to Herrerasauria in the past, but aren't currently thought to be, include-
Aliwalia, a junior synonym of the sauropod Eucnemesaurus.
Alwalkeria, a chimaera of probable eusaurischian and something else (crocodylomorph?).
Protoavis, a chimaera of drepanosaurid, coelophysoid, pterosauromorph, and who knows what else.


Mickey Mortimer