  The character diagnosis of Tenontosaurus tilletti has been revised and
redefined into a more robust and quantifiable state. Significant emphasis is
placed on constructing phylogenetic definition in such a method, as it prevents
occlusion of true character states by alleviating potential individual
interpretational bias. Previous placement within the Iguanodontia is refuted
based on the lack of character affinity with the defining synapomorphies of the
clade. The clade Hypsilophodontidae (=Hypsilophodontia), along with
Iguanodontia, however is deemed to be in critical need of refinement to account
for recent discoveries and re-classifications of certain euornithopods. Several
of the synapomorphies are out-dated and deemed redundant in favour of a more
quantifiable approach. Re- definition of these clades is critical if the
current state of basal euornithopodan relationships is to be resolved.
Phylogenetic studies must be approached from a multidisciplinary perspective;
integration of tectonostratigraphical, ontogenetic, palaeoecological, and
biomechanical data with sets of well-defined primary homologies are essential
in increasing phylogenetic resolution and generating stratigraphically feasible
ancestor-descendant relationships. Material attributed to Tenontosaurus
tilletti is in need of strict re-analysis; the significant quantity of
specimens attributed to this species is potentially the result of poor
stratigraphic constraints and the vast spatiotemporal span occupied. Future
revision of this material is expected to reveal temporal variations on the
species -level inherently linked to environmental evolution, as well as
possibly provide clues to sexual dimorphism in contemporaneous, yet
morphologically distinct tenontosaurs.
