The diversity of fossil crocodylomorphs in Portugal is high, with occurrence as old as Mystriosaurus (=Steneosaurus) bollensis from the Lower Jurassic. The Late Jurassic forms are the better documented, and include the following taxa: Machimosaurus hugii, Lisboasaurus estesi Seiffert, 1973, Lusitanisuchus mitrocostatus Seiffert, 1975; Schwarz & Fechner 2004, Theriosuchus guimarotae Schwarz and Salisbury 2005, Cf. Alligatorium, Goniopholis baryglyphaeus, and a crocodylomorph-like eggs in dinosaur nests (Mateus et al., 1998; Ricqlès et al., 2001). From the Lower Cretaceous were reported a few dinosaurs but its record is strangely scarce in crocodylomorphs (Mateus et al., 2011). The Upper Cretaceous crocodiles show a large diversity, but it is mostly based in fragmentary material that require revision, such as “Crocodylus” blavieri? Grey from the Upper Campanian - Maastrichtian of Viso, near Aveiro (initially reported by Sauvage 1897-98), Goniopholis cf. crassidens Owen 1841 and Oweniasuchus pulchelus Jonet 1981. Moreover there is a fascinating, but poorly understood, crocodylomorph diversity in the Cenomanian of Portugal, documented by fragmentary specimens that have been doubtfully assigned to Thoracosaurus Leidy 1852 of the Middle Cenomanian of Cacém, to the nomen dubium Oweniasuchus lusitanicus Sauvage 1897-98 (interpreted as a mesosuchian goniopholid) based in a fragmentary mandible from the Campanian-Maastrichtian, and also from the Middle Cenomanian of Portugal, Buffetaut and Lauverjat (1978) report an fragmentary unidentified possible dyrosaurid from Nazaré. All this specimens are too incomplete to be compared with the specimen here described. In contrast, Cenozoic crocodiles of Portugal are often known after complete skulls and several individuals. The taxa list include Iberosuchus macrodon (Lower to Middle Eocene), Tomistoma calaritanus (Early Miocene) and T. lusitanica (Burdigalian-Helvetian), and Diplocynodon sp. (Antunes, 1961, 1987, 1994).
At least, two different morphotypes of crocodylomorph eggs from the Late Jurassic of Lourinhã Formation are also known.
A new specimen here reported of crocodile based in a partial skull and mandible (ML1818) from the Uppermost Middle Cenomanian platform carbonates of Baixo Mondego, west central Portugal (Tentúgal Fm., Callapez, 2004). The taxon is phylogenetically positioned as a basal Eusuchia, due to the choanae enclosed by the pterygoid, and closely related with stem Crocodylia and Borealosuchus. This specimen represents the only well documented and valid eusuchian species in the Cenomanian of Europe and is the oldest representative of an eusuchian crocodylomorph, with the exception for the Barremian Hylaeochampsa vectiana.
