''Epoidesuchus'' is an extinct pepesuchine peirosaurid from the Late Cretaceous (

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

)

Adamantina Formation The Adamantina Formation is a geological Formation (geology), formation in the Bauru Basin of western São Paulo (state), São Paulo state in southeastern Brazil. Its strata date back to the Late Cretaceous epoch of the Cretaceous, Cretaceous Per ...

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

. Like other members of the Pepesuchinae and unlike the closely related members of Peirosaurinae, ''Epoidesuchus'' had long and gracile jaws, which may indicate that they were semi-aquatic animals more similar to modern crocodilians. The genus is monotypic, meaning it only contains a single species, ''Epoidesuchus tavaresae''.

History and naming

The holotype specimen of ''Epoidesuchus'' were found in 2011 in outcrops of the

in the

ian municipality of

Catanduva Catanduva is a municipality in the state of São Paulo (state), São Paulo, Brazil. The population is 122,497 (2020 est.) in an area of 290.59 km2. Is the second largest city in the Northern part of the state, after São José do Rio Preto. ...

. The specimen; which consists of a nearly tubular snout, a partial skull roof, parts of the mandible and a single rib; was recovered from a road cut and subsequently sent to the Museu de Paleontologia Professor Antonio Celso de Arruda Campos. The material was first identified as a peirosaurid that same year by Fabiano Iori. The animal was eventually fully described in 2024 and recognized as a distinct species and genus by Juan V. Ruiz and colleagues, who coined the name ''Epoidesuchus tavaresae''. The name ''Epoidesuchus'' is a combination of the

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

"epoide" meaning "enchanted" and "souchus", a commonly used suffix among crocodilians that hearkens back to the Egyptian god

Sobek Sobek (), also known as Suchus (), was an ancient Egyptian deities, ancient Egyptian deity with a complex and elastic history and nature. He is associated with the Nile crocodile and is often represented as a crocodile-headed humanoid, if not a ...

. The use of "epoide" is a reference to the city of Catanduva, which is also known as the "Magic Spell City". The species name on the other hand honors Sandra Simionato Tavares, a paleontologist and the director of the museum that houses the type specimen.

Description

Cranium

The skull of ''Epoidesuchus'' is known from various incomplete remains, including much of the

skull table The skull roof or the roofing bones of the skull are a set of bones covering the brain, eyes and nostrils in bony fishes, including land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium. In comparati ...

, a piece of a lacrimal and a skull fragment that preserves parts of the region that sits before the eyes. Unlike modern crocodiles, ''Epoidesuchus'' possessed a small opening in the skull before the eyes, known as the antorbital fossa. The fossa is separated from the eyesocket by the

lacrimal bone The lacrimal bones are two small and fragile bones of the facial skeleton; they are roughly the size of the little fingernail and situated at the front part of the medial wall of the orbit. They each have two surfaces and four borders. Several bon ...

, with the distance between it and the eyesocket being longer than the fossa itself is high. The skull table is dominated by two large openings, 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 ...

, the rims of which are on level with the rest of the skull roof rather than raised. The skull roof extends the furthest back with the

squamosal bone The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral ...

s, which project back and upward even after their lateral processes connect to the

parietal bone The parietal bones ( ) are two bones in the skull which, when joined at a fibrous joint known as a cranial suture, form the sides and roof of the neurocranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four bord ...

. Notably, beyond this point the bones lack the ornamentation that is present across most the rest of the skull.

Lower jaw

Another largely complete element of ''Epoidesuchus'' is the left hemimandible, which preserves most of the

dentary bone 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 ...

. The size and shape of the mandible suggests that ''Epoidesuchus'' had a long and narrow snout, with the preserved portion alone measuring . It's roughly constant in height safe for a small increase towards the back of the skull. The dentaries are also not compressed mediolaterally but have a convex outer surface, which supports the placement of ''Epoidesuchus'' within Pepesuchinae. The edges of the lower jaw seem to run subparallel to the length of the skull as a whole and don't display noticeable narrowing towards the tip nor widening towards the back. However, there is a noticeable notch in the lower jaw close to the fourth dentary tooth, which might accommodate an enlarged maxillary tooth when the jaws were closed.

Dentition

The lower jaw preserves a total of 14 teeth of varying size and diameter, with the individual teeth and alveoli separated by prominent gaps that likely serve to allow the teeth of the upper and lower jaw to interlock. The distance between the individual teeth or alveoli is relatively consistent throughout the lower jaw, with the exception of the region between the sixth and ninth dentary teeth. The sixth and seventh tooth are very closely spaced, as are the eight and ninth, with prominent diastemas separating them from each other as well as the fifth and tenth dentary teeth. The eight tooth also happens to be the smallest tooth in the lower jaw, whereas the 11th and 13th are the largest. All teeth are laterally compressed, but unlike other peirosaurids they lack the serrations or crenulations that would make them ziphodont or pseudo-ziphodont, something that ''Epoidesuchus'' shares with the African '' Stolokrosuchus''.

Size

The size of the lower jaw indicates that ''Epoidesuchus'' was at least 50% larger than other peirosaurids that inhabited the Adamantina Formation, which includes '' Itasuchus'', '' Pepesuchus'', '' Roxochampsa'' and '' Montealtosuchus''.

Phylogeny

The phylogenetic analysis conducted during the description of ''Epoidesuchus'' recovers a tree that aligns with the so-called "Sebecia hypothesis", meaning that peirosaurids are found to clade with the families

Sebecidae 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. The oldes ...

and

Mahajangasuchidae Mahajangasuchidae is an extinct family (biology), 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 mo ...

. This hypothesis stands opposed to the "Sebecosuchia hypothesis", in which sebecids are most closely related to

baurusuchids Baurusuchidae is a Gondwanan Family (biology), family of mesoeucrocodylians that lived during the Late Cretaceous. It is a group of terrestrial hypercarnivorous crocodilians from South America (Argentina and Brazil) and possibly Pakistan. Baurusu ...

while peirosaurids clade with mahajangasuchids and

uruguaysuchids Uruguaysuchidae is a family (biology), 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 ''Uruguay ...

. Within Peirosauridae, Ruiz and colleagues recovered a clear split between two distinct lineages, peirosaurines and pepesuchines. While the former are described as semi-aquatic to terrestrial animals with oreinirostral snouts (meaning their snouts appeared tall and domed) and includes taxa like '' Hamadasuchus'', '' Uberabasuchus'' and '' Montealtosuchus'', the later consists primarily of animals that are hypothesized to be more aquatic, possessing elongated or flattened snouts as seen in '' Caririsuchus'', '' Roxochampsa'' and '' Pepesuchus''. Though the name Pepesuchinae is used by Ruiz and colleagues to describe the clade, they do note that following the terminology of Pinheiro ''et al.'' 2018 Peirosauridae would be restricted to the clade they dub Peirosaurinae. Their version of Pepesuchinae meanwhile would be separated into the clade Itasuchidae (which would be composed of ''Pepesuchus'' and the recovered polytomy) and various more basal taxa. Subsequently, following this taxonomy ''Epoidesuchus'' would not be regarded as a pepesuchine nor an itasuchid, even though its position would not change. Furthermore, the description of ''Epoidesuchus'' does not take into account the 2024 nomenclature published by Leardi and colleagues, in which they coin the clade Peirosauria, which consists of peirosaurids, itasuchids and mahajangasuchids. Within Peirosauria, Peirosauridae and Itasuchidae are roughly equivalent to the clades Peirosaurinae and Pepesuchinae as recovered by Ruiz and colleagues. Nearly identical results to those of Ruiz and colleagues were later recovered by Wilberg ''et al.'' in 2025, only differing in the inclusion of ''Sissokosuchus'' as the sister taxon to ''Barreirosuchus'' and the use of the Pinheiro ''et al.'' 2018 nomenclature.

Paleobiology

Like several other members of Pepesuchinae, ''Epoidesuchus'' had elongated and narrow jaws that are wildly different from the tall, deep skulls seen in peirosaurines. Such a skull shape is unique among notosuchians, but much more widespread among neosuchians like goniopholidids and modern

crocodilians 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 pseudosuchi ...

, which may suggest a similar semi-aquatic lifestyle. Pepesuchines are however not perfect anatomical analogues to neosuchians, as they still have some adaptations seen in more terrestrial groups. Rather than having eyes located atop the head, as would be useful for laying in ambush with the body submerged, the eyes of ''Epoidesuchus'' faced towards the side of the skull. Considering both these similarities and differences might suggest that though more semi-aquatic than their relatives, pepesuchines such as ''Epoidesuchus'' were still less dependent on water than modern crocodilians. Semi-aquatic habits have also been reported from mahajangasuchine notosuchians, which includes '' Mahajangasuchus'' and '' Kaprosuchus'', as well as the sebecid '' Lorosuchus'', with the latter being much closer in anatomy to pepesuchines. This might suggest some degree of convergence between pepesuchines and ''Lorosuchus'' specifically. Ruiz and colleagues note that pepesuchines often occur in units were neosuchians are rare or even absent. ''Epoidesuchus'' for example was native to Brazil's Adamantina Formation, which is part of the Bauru Group. Though the Bauru Group is renowned for its diverse notosuchian fauna, only a single neosuchian has been recovered from any of the formations that are part of the unit. Said neosuchian is '' Titanochampsa'', which has so far only been found within the sediments of the Marilia Formation.

References

{{taxonbar, from1=Q130131158 Late Cretaceous crocodylomorphs of South America Adamantina Formation Prehistoric pseudosuchian genera Fossil taxa described in 2024 Fossils of Brazil Peirosauridae