''Siquisiquesuchus'' (meaning " Siquisique crocodile" after the town in

Lara Lara may refer to: People * Lara (name), can be a given name or a surname in several languages * Lara (mythology), a naiad nymph, daughter of the river Almo in Ovid's ''Fasti'' Places *Lara (state), a state in Venezuela * Electoral district ...

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

, near where the first described specimens were found) is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

gavialid Gavialidae is a family of large semiaquatic crocodilians with elongated, narrow snouts. Gavialidae consists of two living species, the gharial (''Gavialis gangeticus'') and the false gharial (''Tomistoma schlegelii''), both occurring in Asia. Man ...

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. It is known from cranial remains and a few

postcrania The postcranium ("behind the cranium"; plural: postcrania) or postcranial skeleton in zoology and vertebrate paleontology is the skeleton apart from the skull. The postcranium encompasses the axial skeleton, which includes the entirety of the verte ...

l bones found in

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

-age rocks of the Castillo Formation in northwestern Venezuela.

Description

''Siquisiquesuchus'' is based on the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

MBLUZ–P–5050, a nearly complete skull and lower jaws. It was found near Lara in rocks of the Early Miocene-age Castillo Formation. Two other partial skulls, partial

vertebra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

e, a

thigh bone The femur (; : femurs or femora ), or thigh bone is the only bone in the thigh — the region of the lower limb between the hip and the knee. In many four-legged animals the femur is the upper bone of the hindleg. The top of the femur fits in ...

, partial

upper arm The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the should ...

, and partial shin bone were recovered from another locality. These bones were described by Christopher Brochu and Ascanio Rincón in

2004 2004 was designated as an International Year of Rice by the United Nations, and the International Year to Commemorate the Struggle Against Slavery and Its Abolition (by UNESCO). Events January * January 3 – Flash Airlines Flight 60 ...

. 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 ...

is ''S. venezuelensis''. Like other gavialoids, ''Siquisiquesuchus'' had a long, narrow

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit ** podium * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ...

on its skull, accounting for approximately 60% of the skull's length. The number of teeth 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 mammals h ...

ry bones at the tip of the snout is not known, but the

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 ...

e making up most of the rostrum had at least 20 teeth each, and the dentaries of the lower jaws had at least 23. Some details of the described skulls cannot be determined because the sutures are not visible. ''Siquisiquesuchus'' was found by Brochu and Rincón to be the oldest known gavialoid from South America, sharing various anatomical details with '' Gryposuchus colombianus'' (to which it is particularly similar) and other South American gavialoids. Later studies have concurred with a gavialoid identity, finding the genus to be related to such genera as ''

Gavialis ''Gavialis'' is a genus of crocodylians that includes the living gharial ''Gavialis gangeticus'' and one known extinct species, '' Gavialis bengawanicus.'' ''G. gangeticus'' comes from the Indian Subcontinent, while ''G. bengawanicus'' is know ...

'', ''Gryposuchus'', ''

Ikanogavialis ''Ikanogavialis'' is an extinct genus of gavialid crocodilian. Fossils have been found in the Urumaco Formation in Urumaco, Venezuela and the Solimões Formation of Brazil. The strata from which remains are found are late Miocene in age, rath ...

'', and ''

Piscogavialis ''Piscogavialis'' is an extinct monospecific genus of Gryposuchinae, gryposuchine Gavialidae, gavialid crocodylian. The only species yet known is ''P. jugaliperforatus''. Fossils of ''Piscogavialis'' have been found from the Miocene, Mio-Pliocene ...

''. Vélez–Juarbe and colleagues (2007) found it to be a

gryposuchinae Gryposuchinae is an extinct subfamily of gavialid crocodylians. Gryposuchines lived mainly in the Miocene of South America. However, '' "Ikanogavialis" papuensis'' may have survived more recently, into the Late Pleistocene/Holocene. Most were lo ...

, while Jouve and colleagues (2008) did not assign families or subfamilies. Brochu and Rincón noted that ''Siquisiquesuchus'' was found in marginal marine deposits. This, along with similarities to

Old World The "Old World" () is a term for Afro-Eurasia coined by Europeans after 1493, when they became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia in the Eastern Hemisphere, previously ...

gavialoids, was interpreted as evidence that gavialoids "dispersed across a marine barrier to the

Neotropics The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeog ...

during the

Tertiary Tertiary (from Latin, meaning 'third' or 'of the third degree/order..') may refer to: * Tertiary period, an obsolete geologic period spanning from 66 to 2.6 million years ago * Tertiary (chemistry), a term describing bonding patterns in organic ch ...

References

{{Taxonbar, from=Q7525885 Gavialidae Prehistoric pseudosuchian genera Neogene crocodylomorphs Miocene reptiles of South America Friasian Santacrucian Colhuehuapian Neogene Venezuela Fossils of Venezuela Fossil taxa described in 2004