originally defined, the Protorosauria referred to the group containing Protorosaurus and Prolacerta, and included the "Prolacertiformes" as a subdivision. In 1997, Nour-Eddine Jalil conducted an analysis of the "Prolacertiformes"; this analysis expanded its definition to include 14 genera, including the Tanystropheidae. Subsequent research has generally found that Prolacerta was closer to the Archosauriformes than Protorosaurus, making the "Prolacertiformes" non-monophyletic (i.e., composed of several groups that were not sister groups). This research also suggested that the remaining protorosaurs – including Protorosaurus, tanystropheids, and drepanosaurs in some studies – did not necessarily form a monophyletic group. An increasing number of analyses have found a non-monophyletic Protorosauria with Protorosaurus as being more basal (less specialised) than the Tanystropheidae, and drepanosaurs outside Archosauromorpha altogether. In the original description of Dinocephalosaurus, Li recognized the postorbital region and the elongated cervical centra as being indicative of a close relationship with Tanystropheus, which led him to assign it to the Tanystropheidae. However, Rieppel and colleagues subsequently noted characteristics that distinguished Dinocephalosaurus from derived protorosaurs such as Tanystropheus, Macrocnemus, Langobardisaurus, and Tanytrachelos; these include the lack of tapering at the front end of the nasal and an unreduced contribution of the ilium to the acetabulum. This led Rieppel and colleagues to consider Dinocephalosaurus as an indeterminate protorosaur, with its neck elongation having been convergent upon that of Tanystropheus. Their phylogenetic tree, based on a dataset derived from the separate analyses of Jalil (1997), David Dilkes (1998), and Michael Benton & Jackie Allen (1997), is reproduced below, at left. Topology A: Rieppel et al. (2008)Topology B: Liu et al. (2017) Liu and colleagues published a separate phylogenetic analysis in 2017. They criticized the analysis of Rieppel and colleagues as having unnecessarily repeated several characters in their data, thus imbuing the repeated characters with undue weight in the analysis. In their own analysis, Liu and colleagues used the same source datasets, but deleted repeated characters, added two new characters from an analysis by Sean Modesto and Hans-Dieter Sues (2004), and removed poorly preserved or potentially chimeric taxa such as Cosesaurus, Kadimakara, Trachelosaurus, and Malerisaurus. Analyses based on parsimony-based and Bayesian methods found that Dinocephalosaurus was a member of the Tanystropheidae, being the sister group to a monophyletic group containing Tanystropheus, Macrocnemus, Langobardisaurus, and Tanytrachelos. The analyses also recovered a monophyletic Protorosauria, albeit to the exclusion of Prolacerta. The tree from the parsimony-based analysis is reproduced above, at right. Several subsequent