Open Paleo

Rhabdodontomorpha

Dieudonné et al., 2016

Its genera lived 125.8–66.0 million years ago Early Cretaceous–Late Cretaceous
Early Cretaceous and Late Cretaceous stages

Rhabdodontomorpha is a clade of early-diverging iguanodontian ornithopods, small to large plant-eaters thought to have split from other iguanodont lineages as far back as the Middle Jurassic. It brings together the family Rhabdodontidae, whose short-snouted members such as Zalmoxes and Mochlodon are known largely from Europe, and, in the analyses of Fonseca and colleagues (2024), Tenontosauridae, a North American clade of Tenontosaurus, Convolosaurus and Iani; many other analyses place Tenontosaurus outside the group (Dieudonné and colleagues, 2020). Iani, from North America, is somewhat transitional in some features between Tenontosaurus and other rhabdodontomorphs (Zanno and colleagues, 2023). Other members reach into Gondwana, including the Australian Fostoria. Together these animals span much of the Cretaceous and retain a number of plesiomorphic ornithopod features.

Diagnosis

  1. Subrectangular maxillary process of the jugal overlapping the maxilla with parallel dorsal and ventral margins
  2. Strongly anteroposteriorly bowed humeral shaft
  3. Lateral deflection of the preacetabular process of the ilium of at least 30 degrees
  4. Transversely expanded, shelf-like dorsal margin of the preacetabular process

Clades within Rhabdodontomorpha

Genera placed directly in Rhabdodontomorpha

  • Foskeia Dieudonné et al., 2026 Barremian–Aptian (125.8–113.2 Ma)Spain
  • Iani Zanno et al., 2023 Cenomanian (100.5–93.9 Ma)United Statesunder dispute
  • Obelignathus Czepiński & Madzia, 2025 Campanian–Maastrichtian (83.6–66.0 Ma)Franceunder dispute
  • Transylvanosaurus Augustin et al., 2022 Maastrichtian (72.2–66.0 Ma)Romaniaunder dispute

References

  1. Dieudonné, P. E.; Tortosa, T.; Torcida Fernández-Baldor, F.; Canudo, J. I.; Díaz-Martínez, I. (2016). An unexpected early rhabdodontid from Europe (Lower Cretaceous of Salas de los Infantes, Burgos Province, Spain) and a re-examination of basal iguanodontian relationships. PLOS ONE 11: e0156251. doi:10.1371/journal.pone.0156251

    Erected Rhabdodontomorpha.

    dieudonné2016a
  2. Madzia, D.; Arbour, V. M.; Boyd, C. A.; Farke, A. A.; Cruzado-Caballero, P.; Evans, D. C. (2021). The phylogenetic nomenclature of ornithischian dinosaurs. PeerJ 9: e12362. doi:10.7717/peerj.12362

    Provides the modern phylogenetic definition of Rhabdodontomorpha.

    madzia2021a
  3. Fonseca, A. O.; Reid, I. J.; Venner, A.; Duncan, R. J.; Garcia, M. S.; Müller, R. T. (2024). A comprehensive phylogenetic analysis on early ornithischian evolution. Journal of Systematic Palaeontology 22: 2346577. doi:10.1080/14772019.2024.2346577

    Named Tenontosauridae for Tenontosaurus, Convolosaurus and Iani, and recovered it with Rhabdodontoidea within Rhabdodontomorpha.

    fonseca2024a
  4. Dieudonné, P. E.; Cruzado-Caballero, P.; Godefroit, P.; Tortosa, T. (2020). A new phylogeny of cerapodan dinosaurs. Historical Biology 33(10): 2335-2355. doi:10.1080/08912963.2020.1793979

    Recovered Tenontosaurus as the basalmost iguanodontian, outside Rhabdodontomorpha.

    dieudonné2020a
  5. Zanno, L. E.; Gates, T. A.; Avrahami, H. M.; Tucker, R. T.; Makovicky, P. J. (2023). An early-diverging iguanodontian (Dinosauria: Rhabdodontomorpha) from the Late Cretaceous of North America. PLOS ONE 18(6): e0286042. Public Library of Science (PLoS). doi:10.1371/journal.pone.0286042

    Described Iani as somewhat transitional in some features between Tenontosaurus and other rhabdodontomorphs, noting most analyses do not unite Tenontosaurus with rhabdodontids.

    zanno2023a