''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. The armadillos, whose species are split between the families Dasypodidae and Chlamyphoridae, are the only surviving members of the order. Two grou ...

, related to the modern

armadillo Armadillos () are New World placental mammals in the order (biology), order Cingulata. They form part of the superorder Xenarthra, along with the anteaters and sloths. 21 extant species of armadillo have been described, some of which are dis ...

s. The genus contains two species, ''Utaetus buccatus'' and ''U. magnum''. 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'', 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 adapted 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, especial ...

, 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 ...

''. ''Utaetus'' is considered a primitive member of the Dasypodidae, 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'', another extinct armadillo. In 2021, Claudia Herrera and colleagues named a new species of ''Utaetus'' based on several osteoderms that had been unearthed from the

Middle Eocene The Eocene ( ) is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''Ēṓs'', ' Dawn') a ...

strata of the Upper Lumbrera Formation in Salta Province, Argentina.

Distribution

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

Fossilworks Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...

.org. *

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

Geste Formation The Geste Formation () 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 thickness of , is the ol ...

(

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

) ** Quebrada de los Colorados Formation ( Barrancan)Powell et al., 2011, p. 361. Retrieved April 13, 2019. **

Sarmiento Formation The Sarmiento Formation (Spanish language, 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 y ...

( Barrancan) *

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

Guabirotuba Formation The Guabirotuba Formation is a Bartonian, late Middle Eocene (Divisaderan in the South American land mammal age, SALMA classification) geologic Formation (geology), formation of the Curitiba Basin in Paraná (state), Paraná, Brazil. The formation ...

(

)Sedor et al., 2017. Retrieved April 13, 2019.

References

Bibliography

* *

Description

Classification

Distribution

References

Bibliography

Further reading