 More recently , a 2007 analysis by paleontologist William G. Parker resulted in a larger tree of aetosaur phylogenetics with the inclusion of Heliocanthus . Based on the tree , Parker defined the clades <unk> and <unk> , both within Aetosaurinae . Parker also gave a revised phylogenetic definition of Aetosauria , mentioning that the previous definition , made by Heckert and Lucas in 2000 , was somewhat ambiguous . Heckert & Lucas ( 2000 ) defined Aetosauria as a stem @-@ based taxon , claiming that Aetosauria included all crurotarsans that were more closely related to Desmatosuchus than to the immediate sister group of Aetosauria . Because the immediate sister group of Aetosauria was uncertain , Parker offered a new definition with several non @-@ aetosaur <unk> genera rather than one sister group . According to Parker , Aetosauria included all taxa more closely related to Aetosaurus and Desmatosuchus than to <unk> , Postosuchus , <unk> , <unk> , <unk> , Alligator , <unk> , and Revueltosaurus . 
