''Utaetus'' is an extinct genus of mammal in the order

Cingulata Cingulata, part of the superorder Xenarthra, is an order of armored New World placental mammals. Dasypodids and chlamyphorids, the armadillos, are the only surviving families in the order. Two groups of cingulates much larger than extant armad ...

, related to the modern

armadillo Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along wi ...

s. The genus contains a single species, ''Utaetus buccatus''. It lived in the Late Paleocene to Late Eocene (about 60 to 36 million years ago) and its fossil remains were found in Argentina and Brazil in South America.

Description

This animal, about long, was very similar to a modern armadillo. In particular, the appearance likely recalled that of the modern ''

Euphractus The six-banded armadillo (''Euphractus sexcinctus''), also known as the yellow armadillo, is an armadillo found in South America. The sole extant member of its genus, it was first described by Swedish zoologist Carl Linnaeus in 1758. The six- ...

'', and it already had the typical well-developed xenarthral joints on the vertebrae. Among the other characteristics in common with the modern armadillos, ''Utaetus'' possessed a bony connection between the ischium and the sacrum (this structure was constituted by caudal vertebrae known as pseudosacral) and continuous-growth cylindrical teeth similar to chisels, with wear in the occlusal part. There were ten lower teeth on each side of the jaw; the first two were much smaller and are interpreted as incisors. Unlike later armadillos, however, ''Utaetus'' still had a varying amount of enamel on the lingual and buccal surfaces of the teeth, and the cervical vertebrae were separated (and not co-ossified). The skeleton shows that this animal was suitable for digging, as evidenced by the presence of a large acromion on the scapula and a prominent olecranon on the ulna. The posterior margin of the scapula was thickened, and formed a secondary incipient spine.

Classification

The genus ''Utaetus'' was first described in 1902 by

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 ...

, based on fossil remains initially thought to date back to the Cretaceous. The type species is ''Utaetus buccatus'', also known for cranial material, but Ameghino described further species based on fragmentary remains (''U. deustus'', ''U. lenis'', ''U. laevus'', ''U. laxus''), now considered ''

nomina dubia In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

''. ''Utaetus'' is considered a primitive member of the Dasipodidae, the family that includes the modern armadillos and their extinct relatives. In particular, ''Utaetus'' and its close relatives (such as ''Parutaetus'') could be closely related to the modern genus ''Euphractus''. The name ''Utaetus'' is an anagram of ''

Eutatus ''Eutatus'' is an extinct genus of large armadillos of the family (biology), family Chlamyphoridae. It was endemic to South America from the Miocene, Early Miocene to Late Pleistocene, living from 17.5 Annum, Ma-11,000 years ago, with possible su ...

'', another extinct armadillo.

Distribution

Fossils of ''Utaetus'' have been found in:''Utaetus''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org *

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 ...

Geste Formation The Geste Formation ( es, Formación Geste) is a fossiliferous geologic formation of the Puna Plateau in the western Salta Province and northern Catamarca Province of the Argentine Northwest, northwestern Argentina. The formation, reaching a t ...

(

Divisaderan The Divisaderan age is a South American land mammal age, covering a period of geologic time (42.0–36.0 Ma) within the Middle and Late Eocene epochs of the Paleogene. It follows the Mustersan age and is followed by the Tinguirirican age.

) ** Quebrada de los Colorados Formation ( Barrancan)Powell et al., 2011, p.361 **

Sarmiento Formation The Sarmiento Formation (Spanish: ''Formación Sarmiento''), in older literature described as the Casamayor Formation, is a geological formation in Chubut Province, Argentina, in central Patagonia, which spans around 30 million years from the mid- ...

( Barrancan) *

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Guabirotuba Formation The Guabirotuba Formation is a late Middle Eocene (Divisaderan in the SALMA classification) geologic formation of the Curitiba Basin in Paraná, Brazil. The formation crops out in and around the city of Curitiba and comprises mudstones and san ...

(

)Sedor et al., 2017

References

Bibliography

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Description

Classification

Distribution

References

Bibliography

Further reading