''Duerosuchus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

crocodilian Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest living ...

. Remains have been found from Corrales del Vino in Zamora,

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

, and are middle

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

in age (about 40 million years old). ''Duerosuchus'' is known from a single skull that is incomplete but otherwise well preserved, as well as a lower jaw, some

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 amp ...

s, and possibly some

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

e. ''Duerosuchus'' is a basal crocodilian thought to be closely related to brevirostrine, or short snouted crocodilians, such as

alligatoroid Alligatoroidea is one of three superfamilies of crocodylians, the other two being Crocodyloidea and Gavialoidea. Alligatoroidea evolved in the Late Cretaceous period, and consists of the alligators and caimans, as well as extinct members mor ...

s. However, the genus was not initially included in a

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

study and its position within

Crocodilia Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest living ...

was uncertain, until a 2021 study recovered ''Duerosuchus'' within the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Planocraniidae Planocraniidae is an extinct family (biology), family of eusuchian crocodyliforms known from the Paleogene of Asia, Europe and North America. The family was coined by Li in 1976, and contains three genera, ''Boverisuchus'', ''Duerosuchus'' and '' ...

Discovery

Remains of ''Duerosuchus'' were unearthed by an excavation team from the

University of Salamanca The University of Salamanca ( es, Universidad de Salamanca) is a Spanish higher education institution, located in the city of Salamanca, in the autonomous community of Castile and León. It was founded in 1218 by King Alfonso IX. It is th ...

. The remains were discovered by Luis Alonso Andrés and his son Luis Alonso Santiago, two amateur paleontologists. The genus was first described by Andrés and Santiago in 2009 and was named after the

Duero River The Douro (, , ; es, Duero ; la, Durius) is the highest-flow river of the Iberian Peninsula. It rises near Duruelo de la Sierra in Soria Province, central Spain, meanders south briefly then flows generally west through the north-west part of ...

, as it was found in the Duero River Basin. The

type species In 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 species that contains the biological type specimen ...

is ''D. piscator'', named in reference to its presumed ability to catch fish, inferred from the shape of its teeth.

Description

The skull of ''Duerosuchus'' is around long. The length of the entire animal is estimated to have been around . This estimation is based on the size of the body relative to the skull in similar crocodilians where the body length is known. 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 several ...

skull, known as STUS 14.133, is missing some bones such as those surrounding the

infratemporal fenestra An infratemporal fenestra, also called the lateral temporal fenestra or simply temporal fenestra, is an opening in the skull behind the orbit in some animals. It is ventrally bordered by a zygomatic arch. An opening in front of the eye sockets ...

on the backside of the skull and the

nasal bone The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Eac ...

along the midline of the snout. Despite the lack of some material, the shape of the skull can be inferred from existing bones. The teeth are sharp and recurved with narrow bases. There is a notch in 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 b ...

to accommodate the fourth mandibular tooth of the lower jaw.

Paleobiology

In addition to ''Duerosuchus'', three other Eocene

crocodyliform Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseudo ...

s are known from Corrales: the

sebecia 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 t ...

n ''

Iberosuchus ''Iberosuchus'' (meaning "Iberian crocodile") is a genus of extinct sebecosuchian mesoeucrocodylian found in Western Europe from the Eocene. Remains from Portugal was described in 1975 by Antunes as a sebecosuchian crocodilian. This genus has one ...

'' and the crocodilians ''

Asiatosuchus ''Asiatosuchus'' is an extinct genus of crocodyloid crocodilians that lived in Eurasia during the Paleogene. Many Paleogene crocodilians from Europe and Asia have been attributed to ''Asiatosuchus'' since the genus was named in 1940. These specie ...

'' and ''

Diplocynodon ''Diplocynodon'' is an extinct genus of alligatoroid that lived during the Paleocene to Middle Miocene in Europe. It looked very similar to the modern caiman in that it was small and had bony armour scutes covering its neck, back, belly, and tail ...

''. ''Asiatosuchus'', a large

crocodylid Crocodiles (family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant memb ...

, probably had a similar lifestyle to ''Duerosuchus''. ''Asiatosuchus'', like other large crocodilians, had robust back teeth that were suitable for crushing. It may have preyed on turtles such as '' Allaeochelys'' that were present in the area. While ''Duerosuchus'' may also have preyed on turtles, it was better adapted to catching smaller prey such as fish. Fish are abundant in the sediments from which ''Duerosuchus'' has been found. The University of Salamanca has a collection of Eocene fossils from the area that includes remains of ''Duerosuchus'', ''Asiatosuchus'', ''Iberosuchus'', and many fish and turtle fossils, some of which have bite marks thought to have been made by crocodilians.

References

{{Taxonbar, from=Q5312227 Neosuchians Eocene reptiles of Europe Eocene crocodylomorphs