'' It is not clear where herrerasaurids lie on the early dinosaur evolutionary tree. They are possibly basal theropods or basal saurischians. Early researchers even proposed that they represented an early lineage of
sauropodomorphs. Some analyses, such as Nesbitt
et al. 2009, have found
Herrerasaurus and its relatives in Herrerasauridae to be very basal theropods, while others (such as Ezcurra 2010) have found them to be basal to the clade
Eusaurischia, that is, closer to the base of the saurischian tree than either theropods or sauropodomorphs, but not true members of either. The situation is further complicated by uncertainties in correlating the ages of late Triassic beds bearing land animals. from the Ischigualasto Formation of Argentina,
Staurikosaurus and
Gnathovorax from the
Santa Maria Formation of southern Brazil,
Chindesaurus from the
Petrified Forest (
Chinle Formation) of
Arizona, and possibly
Caseosaurus from the
Dockum Formation of
Texas, although the relationships of the North American animals are not fully understood, and not all paleontologists agree. Grzegorz Niedźwiedzki,
Stephen L. Brusatte et al. (2014) described a
European putative member of the group on the basis of
Norian age fossils discovered in
Poland. An unnamed herrerasaurid was reported from the Carnian
Pebbly Arkose Formation in
Zimbabwe by Griffin
et al. (2022). Other possible basal saurischians include
Alwalkeria from the Late Triassic
Maleri Formation of southern
India, and
Teyuwasu (recently considered synonym of
Staurikosaurus), known from very fragmentary remains from the Late Triassic of Brazil. The discovery of the Herrerasaurid
Gnathovorax indicates that the family falls outside the
Theropoda and
Sauropodomorpha in the cladistic analysis undertaken on the genus when it was described, but remains squarely within
Saurischia as basal members of the order. An unnamed herrerasaurid from the
Carnian of Brazil was described and possibly belongs to a new morphotype of relatively large proportions, informally known as the "Big
Saturnalia". In the phylogenetic analysis within this study, herrerasaurids are recovered as non-
eusaurischian saurischians. Phylogeny Fernando Novas (1992) defined Herrerasauridae as
Herrerasaurus,
Staurikosaurus, and their most recent common ancestor.
Paul Sereno (1998) defined the group as the most inclusive clade including
H. ischigualastensis but not
Passer domesticus. Langer (2004) provided first phylogenetic definition of a higher level
taxon,
Herrerasauria, as
Herrerasaurus but not
Liliensternus or
Plateosaurus. The second cladogram is based on an analysis by Sues
et al. in April 2011. This review classified
Herrerasaurus as a basal theropod. }} }} A large phylogenetic analysis of early dinosaurs by Matthew Baron,
David Norman and Paul Barrett (2017) found Herrerasauridae within the clade
Saurischia, as the
sister group to
Sauropodomorpha. This was the result of the removal of
Theropoda from Saurischia and its placement next to
Ornithischia within the newly created clade
Ornithoscelida. }} Baron & Williams (2018) found Herrerasauria (including
Daemonosaurus,
Caseosaurus and
Saltopus) outside Dinosauria. }} Novas et al., 2021 revised the fossil record of
South American early dinosaurs and supported that Herrerasauria is part of
Saurischia but diverging earlier than both
Sauropodomorpha or
Theropoda, and further corroborated with the hypothesis that
Chindesaurus,
Daemonosaurus and
Tawa are members of the clade. In 2024, Andrea Cau reclassified Herrerasauria within Theropoda. In 2026, during the description of
Ptychotherates, Srivastava & Nesbitt found that Herrerasauria is basal to Saurischia, using the Ezcurra et al data set, and named the new clade
Morphoraptora (, or more loosely meaning "bodysnatcher") to house
Ptychotherates with
Chindesaurus, Tawa and
Daemonosaurus, placing them as the sister taxa to Herrerasauridae. Below is the cladogram from their study, using the dataset of Ezcurra et al. (2023). ==Timeline of genera==