Montsecosuchus is an extinct genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of atoposaurid

Atoposauridae

Atoposauridae is a family of crocodile-like archosaurs. Members of the family have been found from France, Spain, Portugal, Romania, Germany, Kazakhstan, the United Kingdom, the United States, Cameroon, and Thailand.-Phylogeny:...

 crocodylomorph

Crocodylomorpha

The Crocodylomorpha are an important group of archosaurs that include the crocodilians and their extinct relatives.During Mesozoic and early Tertiary times the Crocodylomorpha were far more diverse than they are now. Triassic forms were small, lightly built, active terrestrial animals. These were...

. It is the replacement generic name for Alligatorium depereti, which was described in 1915 from the Montsec Lithographic Limestone

Lithographic Limestone

Lithographic limestone is hard limestone that is sufficiently fine-grained, homogeneous and defect free to be used for lithography. Geologists use the term lithographic texture to refer to a grain size under 1/250 mm...

 quarry

Quarry

A quarry is a type of open-pit mine from which rock or minerals are extracted. Quarries are generally used for extracting building materials, such as dimension stone, construction aggregate, riprap, sand, and gravel. They are often collocated with concrete and asphalt plants due to the requirement...

 of Spain

Spain

Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

. Fossils found from this locality are from the Early Cretaceous

Early Cretaceous

The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...

, being Upper Berriasian

Berriasian

In the geological timescale, the Berriasian is an age or stage of the Early or Lower Creteceous. It is the oldest or lowest subdivision in the entire Cretaceous. It spanned between 145.5 ± 4.0 Ma and 140.2 ± 3.0 Ma...

-Lower Valanginian

Valanginian

In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 140.2 ± 3.0 Ma and 136.4 ± 2.0 Ma...

 in age. While many publications concerning atoposaurids after 1915 have included mentions of A. depereti, none have offered a redescription or revision of the species, even though some recognized that there were great differences between it and other members of the genus. It was noted in these publications that the skull of A. depereti was shorter in relation to body length than any other species of Alligatorium

Alligatorium

Alligatorium is an extinct genus of atoposaurid crocodylomorph. Alligatorium remains have been found in Germany and Mongolia. There are several species included within the genus. The type species is A. meyeri, named in 1871. Other species include A. franconicum, named in 1906, and A paintenense,...

(being less than half of the presacral length), and that this may have been evidence for the genetic distinction of the species, although no replacement name was proposed. However, better preparation of the holotype specimen MGB 512, a nearly complete articulated skeleton embedded in a limestone matrix now housed in the Museo de Geología del Ayuntameinto de Barcelona, allowed for a revision of the species in 1990 in which the name Montsecosuchus was first used.

Montsecosuchus differs in several ways from other atoposaurids such as Alligatorium, Alligatorellus

Alligatorellus

Alligatorellus is a genus of atoposaurid crocodyliform found in France that was related to Atoposaurus.A skeleton of Alligatorellus has also been found in the Solnhofen Limestone of Kelheim, Germany. The limestone was deposited in a marine environment and the individual may have washed into a...

, and Theriosuchus

Theriosuchus

Theriosuchus is an extinct genus of atoposaurid mesoeucrocodylian from the Late Jurassic of Europe, the Early Cretaceous of Asia and the Late Cretaceous of Romania. The five species are T. pusillus from England , T. ibericus from Spain , T. guimarotae from Portugal , T. sympiestodon from Romania...

. Several characteristics of the skull including the presence of an ungrooved parietal

Parietal bone

The parietal bones are bones in the human skull which, when joined together, form the sides and roof of the cranium. Each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is named from the Latin pariet-, wall....

-squamosal

Squamosal

The squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...

 suture and a caudally projecting retroarticular process distinguish Montsecosuchus from these genera. Both Montsecosuchus and Alligatorellus possess three sacral vertebrae: this may be a shared synapomorphy of the two genera. The shortness of the radius

Radius

In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...

is an autapomorphy of the genus that is not seen in any other atoposaurid, although it is common in more derived crocodylomorphs.