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Clade
Subclade

Taxon
Taxon
Herrerasauridae
Nominal Author
Benedetto 1973
2nd Nominal Author
Taxon Status ACTIVE
Comments

Novas (1992) was first to attempt a definition for Herrerasauridae, strongly implying a node-based concept. His exact wording, strictly speaking, did not specify a complete definition but rather a clade with three members: Herrerasaurus, Staurikosaurus, and their common ancestor. In 1997, Novas clarified its meaning as a node-based taxon.

Sereno (1998) coined a stem-based definition for Herrerasauridae, anchored on Herrerasaurus ischigualastensis. This was done because of the uncertain affinities of a growing number of taxa, such as Chindesaurus bryansmalli from North America. It seems to have affinity with Herrerasaurus, but is it within Herrerasauridae as defined by Novas or positioned as its sister taxon? Sereno (1998) offered a second-order revision as a stem-based group, because of the utility in refering to the entire sister clade of basal theropods generally referred to as herrerasaurids rather than just a subset. The active definition uses species as specifiers. There seems to be little need to add other specifiers, because even if Herrerasauridae is positioned outside other theropods, as some have advocated (e.g. Novas 1992, Fraser et al. 2002; Langer 2004), this stem-based definition advocated here would identify the same clade.

Langer (2004) coined a new stem-based taxon Herrerasauria to accomplish exactly what Sereno (1998) did with a stem-based Herrerasauridae. There are so few species in this basal clade, does it truly warrant yet another higher level taxon, Herrerasauria? The active definition, thus, is a first-order revision of the definition of Herrerasauridae given in Sereno (1998) using species as specifiers.

Potential Synonomy

Active Phylogenetic Definition
Active Definition
The most inclusive clade containing Herrerasaurus ischigualastensis Reig 1963 but not Passer domesticus (Linnaeus 1758).
Shorthand
> Herrerasaurus ischigualastensis but not Passer domesticus.
Definitional Author
Sereno 2005
Definition Status checked
Definition Type STEM
Node-Stem Triplet NO
Other Triplet Taxa
Specifiers
Specifier(s) A
Herrerasaurus ischigualastensis
Specifier(s) B
Specifier(s) C
Passer domesticus
Qualifiers
+Taxon
-Taxon
Datum
Taxonomic Content
Publication Year Unknown
Unknown
Unknown
1998

Inactive Taxon Status
Rejection Criteria
Critique
 

Definitional History #1
Earliest Record
Herrerasaurus and Staurikosaurus and their most recent common ancestor.
Latest Record
Novas 1992:55
Range (My)
Range (My)
Herrerasaurus, Staurikosaurus
Range (My)

Definitional History #2
Earliest Record
The common ancestor of the previosuly mentioned species [Herrerasaurus ischigualastensis, Staurikosaurus pricei] plus all its descendants.
Latest Record
Novas 1997:304
Range (My)
Range (My)
Herrerasaurus ischigualastensis, Staurikosaurus pricei
Range (My)

Definitional History #3
Earliest Record
All theropods closer to Herrerasaurus than to Neornithes.
Latest Record
Sereno 1998:64
Range (My)
Range (My)
Herrerasaurus, Neornithes
Range (My)

Definitional History #4
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Definitional History #9
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Definitional History #10
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