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Clade
Subclade Archosauria: Crurotarsi to Crocodylia 
Taxon Feedback
Taxon Aetosauria 
Nominal Author Nicholson and Lydekker 1889 
2° Nominal Author  
Taxon Status active
inactive
Comments First defined by Heckert and Lucas (2000), the active definition is a first-order revision that uses the nominotypical taxon Aetosaurus ferratus as an internal specifier, rather than Desmatosuchus haplocerus, and uses nested species from several other major clades as external specifiers (Rauisuchus tiradentes, Prestosuchus chiniquensis, Poposaurus gracilis, Crocodylus niloticus). In this manner the contents of the clade are stable realtive to other clades but newfound basal aetosaurians may be incorporated. 
Potential Synonomy Aethosauri (Jaekel 1911, spelling variant) 
Active Phylogenetic Definition Feedback
Active Definition The most inclusive clade containing Aetosaurus ferratus Fraas 1877 but not Prestosuchus chiniquensis Huene 1942, Rauisuchus tiradentes Huene 1942, Poposaurus gracilis Mehl 1915, Crocodylus niloticus (Laurenti 1768). 
Shorthand > Aetosaurus ferratus but not Prestosuchus chiniquensis, Rauisuchus triradentes, Poposaurus gracilis, Crocodylus niloticus. 
Definitional Author Sereno 2005 
Definition Status original
textual substitution
first-order revision
second-order revision
Definition Type node
stem
Node-Stem Triplet yes
no
Other Triplet Taxa  
Specifiers
Specifier A Aetosaurus ferratus 
Specifier(s) B  
Specifier(s) C Prestosuchus chiniquensis, Rauisuchus triradentes, Poposaurus gracilis, Crocodylus niloticus 
Qualifiers
+Taxon  
-Taxon  
Datum  
Taxonomic Content stem (entirely extinct)
crown (extant-bounded)
mixed (extant/extinct-bounded)
Publication Year 2000 
Inactive Taxon Status Feedback
Rejection Criteria junior synonym
historically polyphyletic
incomplete definition
no definition
apomorphy-based
redundant
other 
Critique  
 
Current Age Range Feedback
Earliest Record Carnian (228 Ma) 
Latest Record Norian (204 Ma) 
Range (My) 24 
Basis for Range The earliest records are Longosuchus meadi and Coahomasuchus kahleorum from the Carnian-age Chinle Formation of western North America (Heckert and Lucas 2000). The latest record is Neoaetosauroides engaeus from the Norian-age Los Colorados Formation of northwest Argentina (Bonaparte 1967). Dates are rounded to the nearest million, the earliest from the beginning of the stage and the latest from the end of the stage (Gradstein et al. 2004). 
Definitional History #1
Definition 1 All crurotarsans more closely related to Desmatosuchus than the immediate sister group, recognizing that the sister group may be rauisuchians, prestosuchians or another suchian taxon. 
Author Heckert and Lucas 2000:1544 
Type node  stem 
Specifiers Desmatosuchus, rauisuchians, prestosuchians, “another suchian taxon” 
Qualifiers