Hallopus was a prehistoric reptile, named in 1877 as a species of Nanosaurus and classified as a genus by O. C. Marsh in 1881 from the Late Jurassic Morrison Formation. Today though the animal is thought to be a pseudosuchian more closely related to crocodilians. It was redescribed as a sphenosuchian crocodylomorph in 1970, now thought to be a paraphyletic group. It was a quite small animal, reaching a length of 1 m (3.3ft) with long and slender limbs. Macelognathus, a similarly slender-proportioned crocodylomorph to Hallopus, may be synonymous with it.
Trialestes is an extinct genus of Late Triassic (Carnian) crocodylomorphs that lived in South America. It has been classified as a dinosaur in the past due it being adapted as a terrestrial, running carnivore. It is classified in Sphenosuchia, which were early relatives of crocodylians. Irmis, Nesbitt and Sues (2013) noted that some of the material referred to this taxon is actually dinosaurian; however, according to the authors, the holotype specimen PVL 2561, found in the Cancha de Bochas Member of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin in northwestern Argentina, "comprises a single individual that preserves unambiguous crocodylomorph synapomorphies", indicating it is indeed a crocodylomorph, and one of the referred specimens, PVL 3889, does share one or more autapomorphies with the holotype, indicating it represents the same taxon. The type species, T. romeri, was named in 1963.
Sphenosuchia is a suborder of basal crocodylomorphs that first appeared in the Triassic and occurred into the Middle Jurassic. Most were small, gracile animals with an erect limb posture. They are now thought to be ancestral to crocodyliforms, a group which includes all living crocodilians.
Terrestrisuchus is an extinct genus of very small early crocodylomorph that was about 76 centimetres (30 in) long. Fossils have been found in Wales and Southern England and date from near the very end of the Late Triassic during the Rhaetian, and it is known by type and only known species T. gracilis. Terrestrisuchus was a long-legged, active predator that lived entirely on land, unlike modern crocodilians. It inhabited a chain of tropical, low-lying islands that made up southern Britain, along with similarly small-sized dinosaurs and abundant rhynchocephalians. Numerous fossils of Terrestrisuchus are known from fissures in limestone karst which made up the islands it lived on, which formed caverns and sinkholes that preserved the remains of Terrestrisuchus and other island-living reptiles.
Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. Extinct crocodylomorphs were considerably more ecologically diverse than modern crocodillians. The earliest and most primitive crocodylomorphs are represented by "sphenosuchians", a paraphyletic assemblage containing small-bodied, slender forms with elongated limbs that walked upright, which represents the ancestral morphology of Crocodylomorpha. These forms persisted until the end of the Jurassic. During the Jurassic, crocodylomorphs morphologically diversified into numerous niches, with the subgroups Neosuchia and the extinct Thalattosuchia adapting to aquatic life, while some terrestrial groups adopted herbivorous and omnivorous lifestyles. Terrestrial crocodylomorphs would continue to co-exist alongside aquatic forms until becoming extinct during the Miocene.
Litargosuchus is a sphenosuchian crocodylomorph, a basal member of the crocodylomorph clade from the Early Jurassic of South Africa. Its genus name Litargosuchus is derived from Greek meaning "fast running crocodile" and its species name leptorhynchus refers to its gracile snout. Litargosuchus, along with all of South Africa's crocodylomorph taxa, are confined to the upper Elliot Formation (UEF) in South Africa.
Junggarsuchus is an extinct genus of sphenosuchian crocodylomorph from the Middle or Late Jurassic period of China. The type and only species is J. sloani. The generic name of Junggarsuchus comes from the Junggar Basin, where the fossil was found, and the Greek word "souchos" meaning crocodile. The specific name, "sloani" is in honor of C. Sloan, who is credited with finding the holotype.
Notosuchia is a suborder of primarily Gondwanan mesoeucrocodylian crocodylomorphs that lived during the Jurassic and Cretaceous. Some phylogenies recover Sebecosuchia as a clade within Notosuchia, others as a sister group ; if Sebecosuchia is included within Notosuchia its existence is pushed into the Middle Miocene, about 11 million years ago. Fossils have been found from South America, Africa, Asia, and Europe. Notosuchia was a clade of terrestrial crocodilians that evolved a range of feeding behaviours, including herbivory (Chimaerasuchus), omnivory (Simosuchus), and terrestrial hypercarnivory (Baurusuchus). It included many members with highly derived traits unusual for crocodylomorphs, including mammal-like teeth, flexible bands of shield-like body armor similar to those of armadillos (Armadillosuchus), and possibly fleshy cheeks and pig-like snouts (Notosuchus). The suborder was first named in 1971 by Zulma Gasparini and has since undergone many phylogenetic revisions.
Trematochampsidae is an extinct family of mesoeucrocodylian crocodyliforms. Fossils are present from Madagascar, Morocco, Niger, Argentina, and Brazil. Possible trematochampsids have been found from Spain and France, but classification past the family level is indeterminant. The trematochampsids first appeared during the Barremian stage of the Early Cretaceous and became extinct during the late Maastrichtian stage of the Late Cretaceous.
Hoplosuchus is a genus of crocodyliform belonging to Protosuchidae. It is so far only known definitely from one specimen, a skeleton collected from sandstone of the Upper Jurassic-age Morrison Formation rocks at Dinosaur National Monument, Utah, during road construction. The individual was small, approximately 20 centimetres (7.9 in) long, although it may have been very young. It is the basalmost crocodyliform of the Morrison Formation, as suggested by such attributes as still having antorbital fenestrae in the skull. The limbs were relatively long, suggesting that the animal was terrestrial. Two rows of bony scutes ran down the back. The crowns of the teeth are not well preserved, so the diet cannot be determined with certainty. Given its small size, it probably ate insects and small vertebrates; it may have been carnivorous or omnivorous.
Microsuchus is an extinct genus of mesoeucrocodylians, belonging to Notosuchia. Fossils have been found in the Bajo de la Carpa Formation, dating to the Santonian stage of the Late Cretaceous.
Sebecidae is an extinct family of prehistoric terrestrial sebecosuchian crocodylomorphs, known from the Late Cretaceous and Cenozoic of Europe and South America. They were the latest surviving group of non-crocodilian crocodylomorphs.
Sebecia is an extinct clade of mesoeucrocodylian crocodyliforms that includes peirosaurids and sebecids. It was first constructed in 2007 to include Hamadasuchus, Peirosauridae, and Sebecus. It was initially considered to be the sister taxon of the clade Neosuchia, which includes living crocodilians, although some later studies have placed it within Neosuchia as a basal clade. Sebecians were terrestrial crocodyliforms characterized by their deep snouts and ziphodont dentition. They first appeared in the Late Cretaceous, survived the Cretaceous–Paleogene extinction event, and became extinct in the Miocene epoch.
Sebecosuchia is an extinct group of mesoeucrocodylian crocodyliforms that includes the families Sebecidae and Baurusuchidae. The group was long thought to have first appeared in the Late Cretaceous with the baurusuchids and become extinct in the Miocene with the last sebecids, but Razanandrongobe pushes the origin of Sebecosuchia to the Middle Jurassic. Fossils have been found primarily from South America but have also been found in Europe, North Africa, Madagascar, and the Indian subcontinent.
Barcinosuchus is an extinct genus of carnivorous metasuchian from the early Cretaceous period. It is a peirosaurid which lived during the early Cretaceous period in what is now Chubut Province, Argentina. It is known from the holotype MPEF-PV 3095, which consists of skull, mandible, and postcranial remains. The specimen recovered from the lower part of the Cerro Castaño Member of the Cerro Barcino Formation. Barcinosuchus was named by Martín Leardi and Diego Pol in 2009 and the type species is Barcinosuchus gradilis.
Uruguaysuchidae is a family of notosuchian crocodyliforms that lived in South America and Africa during the Cretaceous period. It was formally defined under the PhyloCode in 2024 as "the most inclusive clade containing Uruguaysuchus aznarezi but not Baurusuchus pachecoi, Peirosaurus torminni, Mahajangasuchus insignis, Notosuchus terrestris, and Crocodylus niloticus." Below is a modified cladogram that depicts the preferred reference phylogeny, chosen from Fernández Dumont et al. (2020):
Almadasuchus is an extinct genus of crocodylomorph known from the early Late Jurassic Puesto Almada Member of the e Cañadón Calcáreo Formation of Patagonia, Argentina. It contains a single species, Almadasuchus figarii. It is known from the holotype MPEF-PV 3838, a well-preserved posterior region of the skull as well as other skull and postcranial remains. Almadasuchus was recovered from Puesto Almada, 30 m above the fish beds, dated as Oxfordian in age.
The Cañadón Asfalto Basin is an irregularly shaped sedimentary basin located in north-central Patagonia, Argentina. The basin stretches from and partly covers the North Patagonian Massif in the north, a high forming the boundary of the basin with the Neuquén Basin in the northwest, to the Cotricó High in the south, separating the basin from the Golfo San Jorge Basin. It is located in the southern part of Río Negro Province and northern part of Chubut Province. The eastern boundary of the basin is the North Patagonian Massif separating it from the offshore Valdés Basin and it is bound in the west by the Patagonian Andes, separating it from the small Ñirihuau Basin.
Incertovenator is an extinct genus of archosauriform reptile, likely an archosaur, of uncertain affinities. Its unstable position is a result of possessing a number features found in both the bird-line avemetatarsalian archosaurs and the crocodylian-line pseudosuchians. The type and only known species is I. longicollum, which is known from single specimen discovered in the Late Triassic Ischigualasto Formation of Argentina. Incertovenator is known almost entirely by its vertebral column. This indicates that it had a relatively long neck, leading to its uncertain classification due to the convergent evolution of elongated neck vertebrae in both avemetatarsalian and pseudosuchian archosaurs.
Llanosuchus is an extinct genus of notosuchian mesoeucrocodylian known from the Late Cretaceous Los Llanos Formation in Argentina. It contains a single species, L. tamaensis.
