Mostly fragmentary fossils have been found from several localities in Portugal and are Late Jurassic and Early Cretaceous in age.
[1] L. mitracostatus was originally thought to have been an anguimorph lizard upon its naming in 1970[2][3][4] based on fragmentary jaw remains and isolated teeth found from the Kimmeridgean-age Guimarota Formation in Leiria .
[5][6] However, a later reexamination of fossils from the Guimarota Formation had found skull material that included a dentary similar to the one seen in the holotype of L. mitracostatus.
Several teeth referable to Lusitanisuchus were also found from Porto Dinheiro, Lourinhã in strata deposited during the Berriasian stage of the Early Cretaceous, extending the temporal range of this taxon by about 15 Ma.
Dinosaur fossils found from the Guimarota Formation include tyrannosauroids such as Aviatyrannis and Stokesosaurus, the ornithopod Phyllodon, and the small coelurosaur Compsognathus.