Trimucrodon is a genus of ornithischian dinosaur from the Late Jurassic of Portugal. Three isolated teeth found at the Porto Dinheiro (or Pinhiero) locality in the Lisboa District of Portugal were given the name in 1973 by Richard A. Thulborn, derived from the Latin words for "three" and a dagger point, and , and the Ancient Greek word for "tooth". The only species in the taxon is Trimucrodon cuneatus, taken from the wedge shape of the teeth. Though the unit the specimens came from was originally unnamed, it was referred to the Alcobaça, and then Lourinhã Formations, specifically the late Kimmeridgian Amoreira–Porto Novo Member. The type specimen, uncovered between 1962 and 1967 by German zoologist and paleontologist Georg Krusat, is distinguished by prominent denticles at the front and rear ends of the crown, and comes from an individual under long. It is currently kept in the collections of the Museu Geológico do Instituto Geológico e Mineiro in Lisbon, Portugal, formerly having been kept in the collections of the Free University of Berlin. The holotype tooth of Trimucrodon is wide, similar to some of the referred specimens, with the crown about as tall as wide. Other specimens have crowns as small as wide and only half as tall as wide. The crowns are of varying amounts of asymmetry, though each edge bears the same number of tapering denticles. Tooth enamel is present of an equal thickness on both sides of the tooth crown, and both faces are smooth without ridges. The denticles increase in size away from the apex of the crown, ending with two widely divergent and sharply-pointed denticles at the front and rear ends of the base. Trimucrodon was originally referred to as a member of the ornithopod family Fabrosauridae by Thulborn in 1973, closest to Echinodon but also related to Alocodon and Fabrosaurus. Peter M. Galton retained it in the family in 1978, though he noted that there were significant differences between Trimucrodon and Echinodon, and the Middle to Late Jurassic fabrosaurids Alocodon, Trimucrodon and Echinodon were representative of three independent and only distantly related branches of the family, with Nanosaurus not preserving enough material to determine its relationships. Given that the species was only represented by teeth, Trimucrodon was designated as a nomen dubium in 1990 by David B. Weishampel and Lawrence M. Witmer, as an indeterminate member of Ornithischia outside Ornithopoda. While a basal ornithischian position