Barinasuchus

Barinasuchus (meaning "Barinas crocodile", in reference to where the type material was found) is an extinct genus of sebecid mesoeucrocodylian. It lived in Argentina, Peru, and Venezuela between the middle Eocene and the Late Miocene, ~42–11.6 Ma. Described in 2007, based on a severely damaged specimen from which only a snout tip was recovered, Barinasuchus is known from a single species, B. arveloi, named after Alberto Arvelo Torrealba, a local educator and poet.

The type specimen of Barinasuchus, discovered by road workers in Venezuela in 1973, originally consisted of a substantial portion of the skeleton, though much of it was accidentally destroyed when they attempted to excavate it, leaving only a partial snout and mandible (lower jaw). The specimen comes from the Miocene-age Parángula Formation, and was described in 2007 by Alfredo Paolillo and Omar J. Linares. A second specimen of Barinasuchus was recovered from the Miocene Ipururo Formation of Peru, and was described in 1977 by Éric Buffetaut and Robert Hoffstetter, though was originally assigned to Sebecus huilensis (now Langstonia). Another was recovered from the Eocene-age Divisadero Largo Formation of Argentina in 1984 by Zulma Brandoni de Gasparini.

Barinasuchus' body length has been estimated, based on comparisons with other crocodyliforms, at between 6.3–10 m (21–33 ft), though smaller estimates of 3–4 m (9.8–13.1 ft) were suggested more recently. Its body mass was initially estimated at 1,610–1,720 kg (3,550–3,790 lb), which would make it considerably larger than any terrestrial predatory mammal alive today. However, a smaller estimate of 500 kg (1,100 lb) has since been put forward. Barinasuchus was heterodont, meaning that it possessed two types of teeth. Those of the premaxilla and the front of the maxilla were longer and more conical than those further back, which were shorter and thinner. Its mandible was very robust in comparison to other sebecids, and was widest at the point of the fourth mandibular (lower jaw) tooth. That tooth was very large, and slotted into a prominent notch between the premaxilla and maxilla when the jaws were closed.

Barinasuchus primarily inhabited lacustrine (lake/lakeside) environments. During the Miocene, it inhabited the Pebas Mega-Wetland, or Pebas System, a 390,000 sq mi (1,000,000 km²) expanse of lakes and marshes formed by the growth of the Andes. It, alongside its contemporary relative Langstonia, were part of an endemic northern South American predatory guild which consisted primarily of reptiles and birds. Both were among the last and largest of the sebecids, and significantly outlasted other giant taxa, such as the European Dentaneosuchus, possibly due to their isolation. The extinction of Barinasuchus and other parts of this reptile-heavy guild may have been the result of the loss of the Pebas Mega-Wetland, or the diversification of mammalian predators and the phorusrhacid birds, although this has been questioned by some studies.