''Lomasuchus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

peirosaurid Peirosauridae is a Gondwanan family of mesoeucrocodylians that lived during the Cretaceous period. It was a clade of terrestrial crocodyliforms that evolved a rather dog-like form, and were terrestrial carnivores. It was phylogenetically define ...

notosuchia 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 (see below); if Sebec ...

n known from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

(

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. ...

stage) of Neuquén Province, western central

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...

. It contains a single species, ''Lomasuchus palpebrosus''. Gasparini, Z., Chiappe, L. M. and Fernandez, M. (1991). A new Senonian peirosaurid (Crocodylomorpha) from Argentina and a synopsis of the South American Cretaceous crocodilians. ''Journal of Vertebrate Paleontology'' 11:316-333. It is known only from the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

MOZ 4084 PV which was found in the Loma de la Lata locality of the Neuquén Province,

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and ...

. It was originally reported as collected from sediments of the

Rio Colorado Subgroup Rio or Río is the Portuguese, Spanish, Italian, and Maltese word for "river". When spoken on its own, the word often means Rio de Janeiro, a major city in Brazil. Rio or Río may also refer to: Geography Brazil * Rio de Janeiro * Rio do Sul, a ...

Neuquén Group The Neuquén Group is a group of geologic formations found in Argentina. Rocks in the Neuquén Group fall within the Cenomanian to early Campanian stages of the Late Cretaceous Period. It overlies the older Lohan Cura Formation and is itself over ...

. Later, Hugo and Leanza (2001) noted that this specimen was actually collected from the underlying

Portezuelo Formation The Portezuelo Formation is a geologic formation of Late Cretaceous ( Late Turonian to Early Coniacian) age, outcropping in the Mendoza, Río Negro and Neuquén provinces of Argentina.Rio Neuquén Subgroup Rio or Río is the Portuguese, Spanish, Italian, and Maltese word for "river". When spoken on its own, the word often means Rio de Janeiro, a major city in Brazil. Rio or Río may also refer to: Geography Brazil * Rio de Janeiro * Rio do Sul, a ...

, Neuquén Group. More recent stratigraphic work on this area identified that horizon as belonging to the younger,

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded b ...

-age,

Plottier Formation The Plottier Formation is a geologic formation that outcrops in the Argentine Patagonian provinces of Río Negro and Neuquén. It is the younger of two formations belonging to the Río Neuquén Subgroup within the Neuquén Group of the Neuquén ...

of the Rio Neuquén Subgroup. This horizon is currently considered to pertain to the

-age

Bajo de la Carpa Formation The Bajo de la Carpa Formation is a geologic formation of the Neuquén Basin that crops out in northern Patagonia, in the provinces of Río Negro and Neuquén, Argentina. It is the oldest of two formations belonging to the Río Colorado Subgro ...

of the

. ''Lomasuchus'' had a deep, narrow snout characteristic of peirosaurids. The serrated teeth were compressed, although not to the extent seen in other related genera such as ''

Peirosaurus ''Peirosaurus'' is an extinct genus of peirosaurid crocodylomorph known from the Late Cretaceous period (late Maastrichtian stage) of Minas Gerais, southern Brazil. It contains a single species, ''Peirosaurus torminni''. It is the type genus o ...

''. Many similarities can be seen between its morphology and that of the related ''

Uberabasuchus ''Uberabasuchus'' ("Uberaba crocodile")''Uberabasuchus''
at

'', such as the narrow snout and a groove at the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The ...

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

contact that accommodated for an enlarged fourth mandibular tooth. The two genera are distinguished from one another on the basis of several features, including the shape of the orbits.Carvalho, I. d. S., Ribeiro, L. C. B. and Avilla, L. d. S. (2004). ''Uberabasuchus terrificus sp. nov.'', a new Crocodylomorpha from the Bauru Basin (Upper Cretaceous), Brazil. ''Gondwana Research'' 7(4):975-1002. ''Lomasuchus'' lends its name to a subfamily of peirosaurids called the

Lomasuchinae ''Lomasuchus'' is an extinct genus of peirosaurid notosuchian known from the Late Cretaceous (Santonian stage) of Neuquén Province, western central Argentina. It contains a single species, ''Lomasuchus palpebrosus''. Gasparini, Z., Chiappe, ...

. Lomasuchinae was constructed in 2004 and included ''Lomasuchus'' (the

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nomina ...

), and a

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to confl ...

called

Mahajangasuchini ''Mahajangasuchus'' is an extinct genus of crocodyliform which had blunt, conical teeth. The type species, ''M. insignis'', lived during the Late Cretaceous; its fossils have been found in the Maevarano Formation in northern Madagascar. It ...

, which included ''

Mahajangasuchus ''Mahajangasuchus'' is an extinct genus of crocodyliform which had blunt, conical teeth. The type species, ''M. insignis'', lived during the Late Cretaceous; its fossils have been found in the Maevarano Formation in northern Madagascar. It was ...

'' and ''Uberabasuchus''. ''Mahajangasuchus'' is now placed outside Peirosauridae in a different family,

Mahajangasuchidae Mahajangasuchidae is an extinct family of notosuchian crocodyliforms. It currently contains two genera, ''Mahajangasuchus'' and ''Kaprosuchus'', both of which lived during the Late Cretaceous in Gondwana. It is defined as the most inclusive clad ...

References

Late Cretaceous crocodylomorphs of South America Fossil taxa described in 2012 Terrestrial crocodylomorphs Peirosaurids Bajo de la Carpa Formation Prehistoric pseudosuchian genera {{paleo-archosaur-stub