''Caiman australis'' is an extinct species of

caiman A caiman (also cayman as a variant spelling) is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family, the other being alligators. Caimans inhabit Mexico, Central and South America f ...

described in 1858 on the basis of a left maxilla that was collected from the Upper Miocene age

Ituzaingó Formation The Ituzaingó Formation ( es, Formación Ituzaingó), in older literature also described as Entre Ríos or Entrerriana Formation, is an extensive geological formation of Late Miocene (Tortonian, or Huayquerian in the SALMA classification) age i ...

of Entre Rios,

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

.Bravard, A. (1858). Monografıa de los terrenos marinos terciarios del Paraná. ''Diario oficial del Gobierno: El Nacional Argentino. eprinted as Burmeister, G. 1883.'.Bona, P., & Barrios, F. (2015). The Alligatoroidea of Argentina: an update of its fossil record. ''Publicación Electrónica de la Asociación Paleontológica Argentina'', ''51''.

Etymology

The species name “''australis''” comes from the Greek root ''austral'', which means “southern” after its discovery in South America.

Discovery and taxonomy

''Caiman australis'' was first described by French engineer

Auguste Bravard (Pierre Joseph) Auguste Bravard (18 June 1803 – 28 March 1861) was a French mining engineer turned palaeontologist. He hunted fossils in the Vaucluse, Allier and his native Puy de Dôme. Biography Bravard emigrated to Argentina in the winter of ...

, who had been hired by the Museo de la Confederación, on the basis of a complete left maxilla that had been collected from

Upper Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene Epoch made up of two stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million years ago) to 5.333 Ma. The ev ...

strata belonging to the

along the banks of the Parana River in Entre Ríos Province, Argentina.Bona, P., Riff, D., & de Gasparini, Z. B. (2012). Late Miocene crocodylians from northeast Argentina: new approaches about the austral components of the Neogene South American crocodylian fauna. ''Earth and Environmental Science Transactions of the Royal Society of Edinburgh'', ''103''(3-4), 551-570. Bravard named it '' Crocodilus australis'' in 1858, believing that it was a species of crocodile due to its elongated maxilla. It was the first named “ Mesopotamian” species and the only one known for 2 decades. Bravard gave it a very brief description, but

Hermann Burmeister Karl Hermann Konrad Burmeister (also known as Carlos Germán Conrado Burmeister) (15 January 1807 – 2 May 1892) was a German Argentine zoologist, entomologist, herpetologist, botanist, and coleopterologist. He served as a professor at the Uni ...

and Cayetano Rovereto gave more detailed descriptions in 1883 and 1912 respectively. The species was placed in several genera by different authors, with Juan B. Ambrosetti placing it in '' Proalligator'' in 1887,

Florentino Ameghino Florentino Ameghino (born Giovanni Battista Fiorino Giuseppe Ameghino September 19, 1853 – August 6, 1911) was an Argentine naturalist, paleontologist, anthropologist and zoologist, whose fossil discoveries on the Argentine Pampas, especially ...

placed it in ''

Alligator An alligator is a large reptile in the Crocodilia order in the genus ''Alligator'' of the family Alligatoridae. The two extant species are the American alligator (''A. mississippiensis'') and the Chinese alligator (''A. sinensis''). Additiona ...

'' in 1898, until it was finally placed in ''Caiman'' in 2012. Some additional fossils have been suggested to be from the species, but a lack of overlap prevents definitive assignment.

Description

Due to the fragmentary nature of the holotype, few diagnostic traits are known for ''Caiman australis''. ''C. australis'' had a narrow snout, with a narrower and longer maxilla than living ''Caiman'' species. The 3rd and 4th alveoli are the largest alveoli and are similarly sized, with smaller interalvelovar spaces on the maxilla. The first, second and fifth to ninth alveoli are similar in size, and the third and fourth alveoli are the largest of the maxillary tooth row, a characteristic present in some other ''Caiman'' species. The lateral margin of maxilla is also less festooned than in other ''Caiman'' species, in dorsal and lateral view. The maxilla is also adorned with an unusual predominance of prominent and elongated grooves and bumps.

Paleoenvironment

Fossils of ''Caiman australis'' have been recovered from the

of Entre Rios,

, which preserves vast tidal flats similar to those in the modern day

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technolog ...

and a warm climate. Large, herbivorous notoungulate mammals in the Ituzaingó Formation were widespread, including the toxodontids '' Xotodon'' and '' Adinotherium'', and

litopterns Litopterna (from grc, λῑτή πτέρνα "smooth heel") is an extinction, extinct order of fossil hoofed mammals from the Cenozoic era. The order is one of the five great orders of Meridiungulata, South American ungulates that were endemic to ...

such as '' Brachytherium'', '' Cullinia'', '' Diadiaphorus, Neobrachytherium, Oxyodontherium, Paranauchenia, Promacrauchenia, Proterotherium'' and '' Scalabrinitherium.'' Large, armored glyptodonts like ''

Palaehoplophorus ''Palaehoplophorus'' (also spelled, historically, ''Palaeohoplophorus'') is an extinct genus of glyptodont. It lived from the Middle to the Late Miocene, and its fossilized remains were discovered in South America. Description This animal, lik ...

'', '' Eleutherocercus'', and ''

Plohophorus ''Plohophorus'' is an extinct genus of Glyptodont. it lived from the Late Miocene to the Late Pliocene, and its fossilized remains were discovered in South America. Description Like all glyptodonts, this animal had a large carapace formed by n ...

''Scillato, G. J. (2013). Los Cingulata (Mammalia, Xenarthra) del “Conglomerado Osífero”(Mioceno tardío) de la Formación Ituzaingó de Entre Ríos, Argentina. ''Publicación Electrónica de la Asociación Paleontológica Argentina'', ''14''(1). lived in the area as well as other cingulates like the pampatheres '' Kraglievichia'' and '' Scirrotherium''. Carnivores included the

phorusrhacids Phorusrhacids, colloquially known as terror birds, are an extinct clade of large carnivorous flightless birds that were one of the largest species of apex predators in South America during the Cenozoic era; their conventionally accepted temporal ...

Devincenzia ''Devincenzia'' is an extinct genus of giant flightless predatory birds in the family Phorusrhacidae or "terror birds" that lived during the Early Miocene (Deseadan) Fray Bentos Formation of Uruguay and Late Miocene (Huayquerian) Ituzaingó Form ...

'' and '' Andalgalornis'' and

sparassodonts Sparassodonta (from Greek to tear, rend; and , gen. , ' tooth) is an extinct order of carnivorous metatherian mammals native to South America, related to modern marsupials. They were once considered to be true marsupials, but are now though ...

, with giant crocodilians like ''

Gryposuchus ''Gryposuchus'' is an extinct genus of gavialid crocodilian. Fossils have been found from Argentina, Colombia, Venezuela, Brazil and the Peruvian Amazon. The genus existed during the Miocene epoch (Colhuehuapian to Huayquerian). One recently d ...

'' and ''

Mourasuchus ''Mourasuchus'' is an extinct genus of giant, aberrant caiman from the Miocene of South America. Its skull has been described as duck-like, being broad, flat, and very elongate, superficially resembling '' Stomatosuchus'' from the Late Cretaceo ...

'' in the freshwater.

Bamboo Bamboos are a diverse group of evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, ...

s, coconut palms, and other palms were prevalent.Franco, M. J., & Brea, M. (2015). First extra-Patagonian record of Podocarpaceae fossil wood in the Upper Cenozoic (Ituzaingó Formation) of Argentina. ''New Zealand Journal of Botany'', ''53''(2), 103-116.

References

{{Taxonbar, from=Q113012884 Alligatoridae Miocene crocodylomorphs Miocene reptiles of South America Fossil taxa described in 1858 Fossils of Argentina Ituzaingó Formation Neogene Argentina