Weishampel et al. (2002:69) coined and defined a node-based taxon Rhabdodontidae for several unusual ornithopods from Europe. They did not discuss why they chose a node-based definition, which suffers from the fragmentary nature and unknown relationships of many of the species associate with the group. This situation was aknowldged, but that does little to establish Rhabdodontidae as the “sibling clade Iguanodontia” (Weishampel et al. 2002:65). If one or more of these species falls outside a clade defined by the two species chosen as specifiers, it will lie outside Rhabdodontidae as they have defined it.
The revision implemented here is to use a stem-based definition based on Rhabdodon priscus, a well known member and eponymous species for Rhabdodontidae. Weishampel et al. (2003:68) excluded Rhabdodontidae from Iguanodontia, but this is clearly not how Iguanodontia was previously conceived and defined (Sereno 1986, 1998, 1999a, b). Iguanodontia was used to include all ornithopods more advanced than taxa that were considered hypsilphodontids. Rhabdodon (= Mochlodon) was regarded as an iguanodontian (Sereno 1986) less derived than Camptosaurus (Sereno, 1997:449). This is precisely how Weishampel et al. (2003:fig. 35) have positioned the taxon Rhabdodontidae. For reasons that are not clear, they position Iguanodontia at a less inclusive node on their cladogram.