Open Paleo

Transylvanosaurus

Augustin et al., 2022 TRAN-sil-VAY-no-SOR-us

Named after Transylvania, Romania (from Latin trans, "across", and silva, "forest"), combined with Greek sauros, "lizard" — means "lizard from across the forest"

72.2–66.0 million years ago Maastrichtian, Late Cretaceous
Late Cretaceous stages

Transylvanosaurus is an extinct genus of rhabdodontid ornithopod dinosaur from the Late Cretaceous (Maastrichtian) Hațeg Basin of Romania. The type species is Transylvanosaurus platycephalus, known from a fragmentary skull.

Under dispute

Transylvanosaurus platycephalus was described as a rhabdodontid, recovered in a poorly resolved Rhabdodontidae (Augustin and colleagues, 2022), but Czepiński and Madzia (2025) recover it as an early-diverging rhabdodontomorph outside Rhabdodontidae.

Diagnosis

  1. Proportionately wide frontals with anteroposterior length to mediolateral width ratio of 1.38
  2. Well-developed anteriorly placed transverse frontal crest distally bounding confluent nasal-prefrontal articulation facets
  3. Very long, straight and thin paroccipital processes making only gentle lateral curve, projecting mostly posterolaterally and slightly dorsally
  4. Very prominent and massive prootic processes extending mainly anterolaterally and ventrally
  5. Mediolaterally wide crest-like basal tubera meeting braincase long axis at very flat angle of approximately 140°
  6. Widely splayed basipterygoid processes extending mainly ventrolaterally and slightly anteriorly, diverging approximately 25° from sagittal plane
  7. Well-developed anteroventrally inclined notch on lateral basicranium side, continuous, straight, and semi-circular in cross section

Species

Transylvanosaurus platycephalus Augustin et al., 2022

Type species

From Ancient Greek 'platys' meaning 'wide' and 'kephale' meaning 'head', referring to the unusual width of the skull compared to related taxa.

Holotype
LPB (FGGUB) R.2070 , Laboratory of Paleontology, Faculty of Geology and Geophysics, University of Bucharest
Material
Articulated basicranium and associated left and right frontals
Horizon
Pui Beds Formation, Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
Locality
Bărbat River Valley, near Pui, Hunedoara, Romania Augustin and colleagues (2022) place the holotype in the middle part of the Bărbat River Valley section, slightly south of, and so stratigraphically above, the level dated by palynology to the 'middle' Maastrichtian.

References

  1. Augustin, F. J.; Bastiaans, D.; Dumbravă, M. D.; Csiki-Sava, Z. (2022). A new ornithopod dinosaur, Transylvanosaurus platycephalus gen. et sp. nov. (Dinosauria: Ornithischia), from the Upper Cretaceous of the Haţeg Basin, Romania. Journal of Vertebrate Paleontology 42(2). Informa UK Limited. doi:10.1080/02724634.2022.2133610

    Named Transylvanosaurus and recovered it in a poorly resolved Rhabdodontidae.

    augustin2022a
  2. Czepiński, Ł.; Madzia, D. (2025). Exploring the diversity and disparity of rhabdodontomorph ornithopods from the Late Cretaceous European archipelago. Scientific Reports 15(1). Springer Science and Business Media LLC. doi:10.1038/s41598-025-98083-z

    Recovered Transylvanosaurus as an early-diverging rhabdodontomorph outside Rhabdodontidae.

    czepiński2025a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Treats Transylvanosaurus as a rhabdodontid.

    jones2026a
  4. Therrien, F. (2005). Palaeoenvironments of the latest Cretaceous (Maastrichtian) dinosaurs of Romania: insights from fluvial deposits and paleosols of the Transylvanian and Hațeg basins. Palaeogeography, Palaeoclimatology, Palaeoecology 218(1-2): 15-56. Elsevier BV. doi:10.1016/j.palaeo.2004.12.005 therrien2005a