''Callistoe'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

sparassodont 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 thoug ...

. It lived during the Early

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

, and its fossilized remains were found in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

Description

Unlike most of its relatives, such as '' Proborhyaena'' and ''

Arminiheringia ''Arminiheringia'' is an extinct genus of sparassodont. It lived during the Early Eocene in South America. Description This animal had an exceptionally robust skull with strong teeth. The lower canines were exceptionally long and projected forw ...

'', ''Callistoe'' had a narrow, puny snout, and the shape of its skull resembled that of a

thylacine The thylacine ( , or , also ) (''Thylacinus cynocephalus'') is an extinct carnivorous marsupial that was native to the Australian mainland and the islands of Tasmania and New Guinea. The last known live animal was captured in 1930 in Tasman ...

. ''Callistoe'' lacked the characteristics associated with the ability to climb in its limbs and vertebrae. The shape of its limb joints, the presence of an ossified patella and the shape of the limb bones show that it was limited to a parasagittal gait, and possessed little flexibility in its elbows, wrists, knees and ankles ; ''Callistoe'' probably specialized in walking and running. ''Callistoe'', approximately two meters long, had a slender and light body, and weighed approximately 23 kilograms.

Classification

''Callistoe vincei'' was first described in 2002, based on an almost complete and exceptionally preserved skeleton from the Lumbrera Formation, in the

Salta Province Salta () is a province of Argentina, located in the northwest of the country. Neighboring provinces are from the east clockwise Formosa, Chaco, Santiago del Estero, Tucumán and Catamarca. It also surrounds Jujuy. To the north it borders Boliv ...

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 ...

. Its generic name, ''Callistoe'', derives from

Callisto Callisto most commonly refers to: *Callisto (mythology), a nymph *Callisto (moon), a moon of Jupiter Callisto may also refer to: Art and entertainment *''Callisto series'', a sequence of novels by Lin Carter *''Callisto'', a novel by Torsten Kro ...

, a

nymph A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are ty ...

loved by

Zeus Zeus or , , ; grc, Δῐός, ''Diós'', label=Genitive case, genitive Aeolic Greek, Boeotian Aeolic and Doric Greek#Laconian, Laconian grc-dor, Δεύς, Deús ; grc, Δέος, ''Déos'', label=Genitive case, genitive el, Δίας, ''D� ...

, and transformed by him into a

bear Bears are carnivoran mammals of the family Ursidae. They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Nor ...

to protect her from

Hera In ancient Greek religion, Hera (; grc-gre, Ἥρα, Hḗrā; grc, Ἥρη, Hḗrē, label=none in Ionic and Homeric Greek) is the goddess of marriage, women and family, and the protector of women during childbirth. In Greek mythology, she ...

's wrath. ''Callistoe'' was a member of the family

Proborhyaenidae Proborhyaenidae is an extinct family of metatherian mammals of the order Sparassodonta, which lived in South America from the Eocene (Mustersan) until the Oligocene (Deseadan). Sometimes it has been included as a subfamily of their relatives, the ...

, a clade of

Sparassodont 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 thoug ...

s typical of the Early

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

, usually large-sized and with a robust build.

Paleobiology

Argot & Babot described in 2011 very long and slightly curved claws, quite different from those of other sparassodonts ; their shape suggesting an ability to dig. What appears to be an healed fracture on the front leg of a specimen of ''Callistoe'' indicates that those were used intensively. The slender outer toes of the quite short feet indicates an aptitude for running. ''Callistoe'' lived alongside a large variety of

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 ...

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...

s and small

notoungulate Notoungulata is an extinct order of mammalian ungulates that inhabited South America from the early Paleocene to the Holocene, living from approximately 61 million to 11,000 years ago. Notoungulates were morphologically diverse, with forms resemb ...

s, all animals with fossorial habits, and it is possible that the animal covered large distances and was able to enter the burrows of these animals. As it lived during the Early Eocene, it may be one of the first examples of a predatory mammal with fossorial habits, millions of years before the rise of the first burrowing

mustelidae The Mustelidae (; from Latin ''mustela'', weasel) are a family of carnivorous mammals, including weasels, badgers, otters, ferrets, martens, minks and wolverines, among others. Mustelids () are a diverse group and form the largest family in ...

on other continents.

Bibliography

*Babot, María J.; Jaime E. Powell; Christian de Muizon (2002). "Callistoe vincei a new Proborhyaenidae (Borhyaenoidea, Metatheria, Mammalia) from the Early Eocene of Argentina". Geobios 35 (5): 615–629. doi:10.1016/S0016-6995(02)00073-6. *Argot, C. & Babot, J. 2011. Postcranial morphology, functional adaptations and palaeobiology of Callistoe vincei, a predaceous metatherian from the Eocene of Salta, north-western Argentina. Palaeontology 54, 411–480. {{Taxonbar, from=Q20721931 Sparassodonts Eocene mammals of South America Fossils of Argentina Paleogene Argentina Fossil taxa described in 2002 Prehistoric mammal genera