Clade | |
Subclade |
Taxon | |
Taxon |
Saurischia
|
Nominal Author | Seeley 1888 |
2nd Nominal Author | |
Taxon Status | ACTIVE |
Comments | The active definition is a first-order revision of Sereno (1998) and of the first phylogenetic definition for Saurischia, which was proposed by Gauthier (1986). Gauthier used supraspecific taxa and common names (i.e. Ornithischia and “birds”) as specifiers. Later, formal taxa replaced one specifier (Padian 1997; Triceratops) or both (Sereno 1998; Triceratops, Neornithes). Finally, Langer (2004) used Allosaurus and Stegosaurus as specifiers but did not provide any explanation for that choice. The active definition uses deeply nested species. Saurischian monophyly is not supported by that many synapomorphies; it is conceivable that ornithischians and sauropodomorphs may eventually prove to be more closely related. If that turns out to be the case, then Saurischia would identify the same clade as the taxon Theropoda. To avoid questions of synonomy and to ensure that the name Saurischia is restricted fo a clade composed of theropods and sauropodomorphs but not all dinosaurs, a positive taxon qualifier is added (the derived sauropodomorph Saltasaurus loricatus) that would negate use of the Saurischia if this species were not included. Another phylogenetic arrangement—with ornithischians most closely related to birds (e.g. Galton 1970) than to nonavian theropods or sauropodomorphs—has never been supported by cladistic analysis and is not regarded here as a realistic possibility . |
Potential Synonomy |
Active Phylogenetic Definition | |
Active Definition |
The most inclusive clade containing Passer domesticus (Linnaeus 1758) but not Triceratops horridus Marsh 1889 and including Saltasaurus loricatus Bonaparte and Powell 1980.
|
Shorthand |
> Passer domesticus but not Triceratops horridus + Saltasaurus loricatus. |
Definitional Author |
Sereno 2005 |
Definition Status | checked |
Definition Type | STEM |
Node-Stem Triplet | STEM |
Other Triplet Taxa |
Dinosauria, Ornithischia |
Specifiers | |
Specifier(s) A |
Passer domesticus |
Specifier(s) B | |
Specifier(s) C |
Triceratops horridus
|
Qualifiers | |
+Taxon |
Saltasaurus loricatus |
-Taxon | |
Datum | |
Taxonomic Content | |
Publication Year |
Unknown Unknown Unknown 1986 |
Inactive Taxon Status | |
Rejection Criteria | |
Critique | |
Definitional History #1 | |
Earliest Record | Birds and all dinosaurs that are closer to birds than they are to Ornithischia. |
Latest Record | Gauthier 1986:15 |
Range (My) | |
Range (My) |
birds, Ornithischia |
Range (My) |
Definitional History #2 | |
Earliest Record | All dinosaurs closer to birds than to Ornithischia. |
Latest Record | Padian and May 1993:379 |
Range (My) | |
Range (My) |
birds, Ornithischia |
Range (My) |
Definitional History #3 | |
Earliest Record | All dinosaurs closer to birds than to Triceratops. |
Latest Record | Padian 1997:647 |
Range (My) | |
Range (My) |
birds, Triceratops |
Range (My) |
Definitional History #4 | |
Earliest Record | All dinosaurs closer to Neornithes than to Triceratops. |
Latest Record | Sereno 1998:63 |
Range (My) | |
Range (My) | |
Range (My) |
Definitional History #5 | |
Earliest Record | All dinosaurs more closely related to Tyrannosaurus than to Triceratops. |
Latest Record | Holtz and Osmólska 2004:21 |
Range (My) | |
Range (My) |
Tyrannosaurus, Triceratops |
Range (My) |
Definitional History #6 | |
Earliest Record | All dinosaurs that share a more recent common ancestor with Allosaurus than with Stegosaurus. |
Latest Record | Langer 2004:25 |
Range (My) | |
Range (My) |
Allosaurus, Stegosaurus |
Range (My) |
Definitional History #7 | |
Earliest Record | |
Latest Record | |
Range (My) | |
Range (My) | |
Range (My) |
Definitional History #8 | |
Earliest Record | |
Latest Record | |
Range (My) | |
Range (My) | |
Range (My) |
Definitional History #9 | |
Earliest Record | |
Latest Record | |
Range (My) | |
Range (My) | |
Range (My) |
Definitional History #10 | |
Earliest Record | |
Latest Record | |
Range (My) | |
Range (My) | |
Range (My) |