''Iberosuchus'' (meaning "Iberian crocodile") is a genus of extinct

sebecosuchia Sebecosuchia (meaning "Sobek crocodiles") 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 baurusu ...

n mesoeucrocodylian found in

Western Europe Western Europe is the western region of Europe. The region's extent varies depending on context. The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the Western half of the ancient Mediterranean ...

from the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

. Remains from

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

was described in 1975 by Antunes as a sebecosuchian

crocodilia Crocodilia () is an order of semiaquatic, predatory reptiles that are known as crocodilians. They first appeared during the Late Cretaceous and are the closest living relatives of birds. Crocodilians are a type of crocodylomorph pseudosuchia ...

n. This genus has one species: ''I. macrodon'' (meaning "large toothed). ''Iberosuchus'' was a

carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they ar ...

. Unlike the crocodilians today, they were not aquatic but were instead terrestrial. The first of its

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s were cranial remains found in

, and later more fossils were found in

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

and

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

. They are only known from very fragmentary fossils, elements of the skull, dentary, teeth and

osteoderm Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinct amph ...

History and discovery

Remains of a mesocrocodylian were found in Portugal; it was named ''Iberosuchus macrodon'' in 1975 by Antunes, and is assigned as the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

. It was reclassified as a baurusuchid by Robert Carroll in 1988. In 1996 Ortega and colleges extended their range to France, they analyzed the fragmentary fossils of '' Atacisaurus crassiproratus'' (originally assigned to the tomistomine genus '' Atacisaurus'' by Astre 1931) and then considered it as cf. ''Iberosuchus''.

Description

''Iberosuchus'' has ziphodont teeth that have a laterally compressed tooth crown that had a distally curved apex; anterior-posteriorly elongated dorsal

s that have a keel running through the central median; rugose ornamentations with no pits and cupules; osteoderm lack anterolateral process; the skull is vermiculated; spoon-like premaxilla palatal shelf or mandibular symphysis; notch between

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 mammals h ...

and

maxilla In vertebrates, the maxilla (: maxillae ) 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 two maxil ...

or large 4th mandibular tooth; deep rostrum or

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

. It also had traits that it shared with other metasuchians, the

dentary In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone ...

had lateral depressions and had a prolongation that extends dorsally behind the tooth row; the

splenial The splenial is a small bone in the lower jaw of reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology ...

s are robust, had a big slot-like foramen intermandibularis oralis; had anteriorposteriorly elongated glanoid fossa on articular. Though only known by skull fragments and

s, many artistic reconstructions use its close relatives such as

Sebecus ''Sebecus'' (meaning "Sobek" in Latin) is an extinct genus of Sebecidae, sebecid crocodylomorph from Paleogene period of South America. Like other sebecosuchians, it was entirely terrestrial and carnivorous. The genus is currently represented by ...

which has post cranial remains found as a reference.

Cranial fossils

Premaxilla

There are 3 fossils of the

excavated from

Aumelas Aumelas (; Languedocien dialect, Languedocien: ''Aumelaç'') is a communes of France, commune in the Hérault Departments of France, department in southern France. Geography The neighboring communes are La Boissière, Hérault, La Boissière ...

, one consisting a close to complete right element, a fragmentary right element, and one with both elements pressed up against one another; they all display a very vermiculated surface texture and contain a concave dent where the

tooth lay. Premaxilla foramen is also visible on right element fossil's palatal view and the nares are anterior pointing, the lateral surface has very distinct ornamentation composed of bony ridges that make up the nares lateral margin. The premaxilla contains five alveoli, they increase in diameter towards the distal end and the fourth one being the largest, the last is the same size as the third and does not line up with other alveoli. There are two deep pits lingually right next to the third and fourth alveoli. Right Premaxilla Fossil

Maxilla

There are two

fossils excavated from Robiac and Saint-Martin-de-Londres, both being a fragment of the maxilla. The Robiac specimen is from the right maxilla, a fragment of the posterior part, with two ziphodont tooth crowns that are broken still on it. The Saint-Martin-de-Londres specimen is also the right maxilla, but larger. Both specimen display a vermiculated surface texture; no palatal processes are visible, but ectopterygoid is visible. There are six alveoli on the maxilla, they are compressed and have an oblique shape, with the third one being the largest. There is a dent visible in collars of the alveoli when viewed medially, the walls of the alveoli are clearly separated and is as tall as the maxilla.

Nasal

There is a fragment of the paired nasals recovered from Aumelas, it has a slight convex shape on its dorsal surface. On the center of each nasal is a pair of ventrally opening foramina, each nasal is vertically concaved with a lateral oblique wall, the nasals are narrower in their anterior portion.

Postorbital

There is a close to complete

postorbital The ''postorbital'' is one of the bones in vertebrate skulls which forms a portion of the dermal skull roof and, sometimes, a ring about the orbit. Generally, it is located behind the postfrontal and posteriorly to the orbital fenestra. In some ve ...

fossil found in

, its dorsal surface is vermiculate and bears a distinct anterolateral process with a concave notch that possibly where the palpebral bone sat. The post orbital is orientated vertically, and the cross section has a triangular shape with both sides concaved; the

supratemporal fenestra Temporal fenestrae are openings in the temporal region of the skull of some amniotes, behind the orbit (eye socket). These openings have historically been used to track the evolution and affinities of reptiles. Temporal fenestrae are commonly (al ...

's anterior-lateral edge is formed by the postorbital. In the dorsal view, the posterior of the postorbital insets into a concave and smooth structure deeply.

Mandible

The

specimen was found in the "

Lutetian The Lutetian is, in the geologic timescale, a stage (stratigraphy), stage or age (geology), age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it ...

" fossil site of Issel in France. It has a symphysis that has a spoon-like shape that reaches the 8th alveoli and is the thickest in with at the 4th tooth, the splenial is one-half the length of the symphysis. The

has light started ornamentations and vermiculation, there are a row of vascular foramen that open backwards on the upper part of the dentary, and the lower half has longitudinal depressions on the lateral. There is a surface full of wrinkles on the lateral dorsal side, for muscle attachment to

surangular The surangular or suprangular is a jaw bone found in most land vertebrates, except mammals. Usually in the back of the jaw, on the upper edge, it is connected to all other jaw bones: dentary, angular bone, angular, splenial and articular. It is o ...

Teeth

The teeth that are recovered are all labiolingually compressed with denticles along the edges, hence they are ziphodont, and the crown curves distally. Ibersuchus Tooth

Osteoderm

Multiple

are found in Robiac. They have a tall ridge surrounded by smaller ridges. In some smaller osteoderms, a ridge runs along the length of the osteoderm, joining with two smaller accessory processes and form a cross shape in the dorsal view, ventral side is concaved. Larger osteoderms also have a similar shape, but the main body is flatter with an indented outline, ventral side is flat.

Phylogeny

Below is a simplified

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

from Pol and Powell (2010) showing the relationship between ''Iberosuchus'' and other

ns.

Geology and paleoenvironment

Portugal

The first fossil of ''Ibersosuchus'' consisting of cranial remains was excavated in the Feligueira Grande Formation located in Praia de Vale Furado in the

Leiria District The District of Leiria ( ) is a district located between the Oeste e Vale do Tejo and Centro regions of Portugal, and divided between the traditional provinces of Beira Litoral and Estremadura. It borders on the north with district of Coimbra, ...

. Formation consists of

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

, with gravel and silt, and in the site various mammals and turtles were found such as Paralophiodon cf. leptorhynchum. The formation is composed of ante-

Bartonian The Bartonian is, in the International Commission on Stratigraphy's (ICS) geologic time scale, a stage or age in the middle of the Eocene Epoch or Series. The Bartonian Age spans the time between . It is preceded by the Lutetian and is follow ...

rocks.

Spain

The fossils of ''Ibersosuchus'' excavated in

includes a mandibular element, a snout fragment, teeth and

s. The mandibular element was found in Caenes,

Salamanca Salamanca () is a Municipality of Spain, municipality and city in Spain, capital of the Province of Salamanca, province of the same name, located in the autonomous community of Castile and León. It is located in the Campo Charro comarca, in the ...

Province in

; it from the

age in MP 16 ( mammal Paleogene zone), which is roughly 44 to 39 million years ago. The other is snout fragment Tosalet del Morral of Lerida province in

, from the

age. The teeth and

s are from Cuenca del Duero,

from Lutetian age, MP13-14 which is in the mid-

France

The fossils of ''Ibersosuchus'' from

include postcranials, cranial elements, teeth, mandibular elements and

. In La Livinière,

Hérault Hérault (; , ) is a departments of France, department of the Regions of France, region of Occitania (administrative region), Occitania, Southern France. Named after the Hérault (river), Hérault River, its Prefectures in France, prefecture is M ...

, France, the postcranials, jugal, and some teeth are found in a fossil site of rocks from late

age, MP 15. The site is 1.5 km west of a village in La Livinere, in a bank of the Ognon river; in the same site there are many Lophiodon, as well as

artiodactyls Artiodactyls are placental mammals belonging to the order Artiodactyla ( , ). Typically, they are ungulates which bear weight equally on two (an even number) of their five toes (the third and fourth, often in the form of a hoof). The other thre ...

. Mandibular elements were recovered in Issel,

Aude Aude ( ; ) is a Departments of France, department in Southern France, located in the Occitania (administrative region), Occitanie Regions of France, region and named after the river Aude (river), Aude. The departmental council also calls it " ...

, France, from late Lutetian age, MP 14. Osteroderm are uncovered in Lissieu,

Rhône The Rhône ( , ; Occitan language, Occitan: ''Ròse''; Franco-Provençal, Arpitan: ''Rôno'') is a major river in France and Switzerland, rising in the Alps and flowing west and south through Lake Geneva and Southeastern France before dischargi ...

, France from late Lutetian age, MP 14. The site was in central eastern

but no longer exists; was located west of Mount d'Or Lyonnais which is a small mount made of limestone 10 km north-northwest of Lyon. Along with Iberosucus, the site yielded fossils of squamates, such as iguanids, Varanoid, serpents etc. Many cranial elements, osteoderm and teeth were found in southern France in Laguedoc;

site has the oldest fossils found at the site were dated back to mid Lutetian age, MP 13; Saint-Martin-de-Londres site was dated to later Lutetian or Bartonia at around MP 15, this site is composed of a base of

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

with many freshwater

gastropods Gastropods (), commonly known as slugs and snails, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and from the land. Ther ...

, many

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

s, and many reptilian fauna; Robiac site was dated to be in the

age, MP 16.

References

{{Taxonbar, from=Q5983971 Fossil taxa described in 1975 Eocene crocodylomorphs Eocene reptiles of Europe Notosuchia Fossils of Portugal Fossils of France Fossils of Spain Prehistoric pseudosuchian genera