Open Paleo

Trimucrodon

Thulborn, 1973 try-MYOO-kro-don Nomen dubium

From Latin tri- ('three') and mucro ('dagger point' or 'sharp tip'), and Greek odous ('tooth'), meaning 'three-pointed tooth', referring to the tricuspid teeth

154.8–149.2 million years ago Kimmeridgian, Late Jurassic
Late Jurassic stages

Trimucrodon is a genus of ornithischian dinosaur from the Late Jurassic Lourinhã Formation of Portugal. The type, and currently only, species is T. cuneatus.

Under dispute

Trimucrodon cuneatus is based on three isolated tricuspid teeth — one designated as the holotype — from the Late Jurassic of Portugal, and its validity is contested. Thulborn (1973) diagnosed it on tooth-crown characters, notably the strongly divergent, prominent foremost and hindmost marginal denticles, and referred it to the now-abandoned Fabrosauridae. Weishampel and Witmer (1990) treated it as a nomen dubium, an indeterminate ornithischian outside Ornithopoda. Sereno (1991) declined that assessment — made, Sereno noted, without comparison — and considered the taxon poorly established but distinct on its denticle pattern, placing it at Ornithischia incertae sedis. Weishampel and colleagues (2004) again regarded it as dubious while allowing that further study could support its validity. It is placed conservatively at Ornithischia incertae sedis.

Species

Trimucrodon cuneatus Thulborn, 1973 Nomen dubium

Type species

From Latin 'cuneatus' meaning 'wedge-shaped', referring to the wedge shape of the teeth.

Holotype
Not catalogued , Museu Geológico do Instituto Geológico e Mineiro (uncatalogued)
Material
A single tricuspid tooth crown; two additional crowns are referred to the species.
Notes
Thulborn (1973) designated a single tooth crown as holotype but assigned no catalog number; originally held at the Free University of Berlin, now at the Museu Geológico, Lisbon.
Horizon
Praia da Amoreira-Porto Novo Member, Lourinhã Formation, Kimmeridgian, Late Jurassic , 154.8–149.2 million years ago
Locality
Porto Dinheiro, Lisbon, Portugal

References

  1. Mateus, O.; Milàn, J. (2009). A diverse Upper Jurassic dinosaur ichnofauna from central-west Portugal. Lethaia 43: 245-257. doi:10.1111/j.1502-3931.2009.00190.x

    Names Porto Dinheiro as the stratotype of Trimucrodon cuneatus, in the Lourinhã Formation.

    mateus2009b
  2. Thulborn, R. A. (1973). Teeth of ornithischian dinosaurs from the Upper Jurassic of Portugal, with description of a hypsilophodontid (Phyllodon henkeli gen. et sp. nov.) from the Guimarota lignite. Memórias dos Serviços Geológicos de Portugal 22: 89-134.

    Erected Trimucrodon cuneatus, designating a single tooth crown as holotype and providing the original tooth-based diagnosis.

    thulborn1973a
  3. Weishampel, D. B.; Witmer, L. M. (1990). Lesothosaurus, Pisanosaurus, and Technosaurus. The Dinosauria (Weishampel, D. B.; Dodson, P.; Osmólska, H., eds.) 416-425. University of California Press, Berkeley.

    Treated Trimucrodon as a nomen dubium, an indeterminate ornithischian outside Ornithopoda.

    weishampel1990a
  4. Sereno, P. C. (1991). Lesothosaurus, 'fabrosaurids,' and the early evolution of Ornithischia. Journal of Vertebrate Paleontology 11(2): 168-197. doi:10.1080/02724634.1991.10011386

    Declined the nomen-dubium assessment and considered the taxon poorly established but distinct, placing it at Ornithischia incertae sedis.

    sereno1991a
  5. Weishampel, D. B.; Dodson, P.; Osmólska, H. (eds.) (2004). The Dinosauria, Second Edition. University of California Press, Berkeley.

    Regarded Trimucrodon as dubious while allowing that further study could support its validity.

    weishampel2004a
  6. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Treats Trimucrodon as an indeterminate ornithischian.

    jones2026a