''Thylophorops'' is an extinct genus of

didelphine Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 93 species in 18 genera. Opossums originated in South America and entered North A ...

opossums Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 93 species in 18 genera. Opossums originated in South America and entered North A ...

from the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58South 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 sou ...

. Compared to their close didelphine cousins like the living '' Philander'' and '' Didelphis'' (and like the still living ''

Lutreolina ''Lutreolina'' is a genus of opossum found in South America. Both extant species in this genus are known as lutrine opossums. They have an otter-like body plan and occasionally semiaquatic tendencies, hence the genus name ''Lutreolina'', which i ...

'') opossums, ''Thylophorops'' displays specialization towards

carnivory A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other so ...

, and one species, ''T. lorenzinii'', is the largest known opossum of all time, which could imply a macropredatory role.

Taxonomy

''Thylophorops'' is rather consistently recovered as a

opossum, most often compared to and usually falling within the '' Didelphis'', '' Philander'' and ''

'' group. Within ''Thylophorops'' itself, there are three recognized species: * ''Thylophorops chapadmalensis'': The type species, known from the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Chapadmalalan The Chapadmalalan age is a period of geologic time (4.0–3.0 Ma) within the Pliocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Montehermosan and precedes the Uquian age. Fossil content Fo ...

)

Chapadmalal Formation Chapadmalal compound is an official retreat of the President of Argentina. It is located on the southern coast of Mar del Plata, in the Buenos Aires Province, and serves as a summer residence. It has a hotel complex nearby. The compound was buil ...

and other (up to Uquian) formations in

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 List of South American countries by area, second-largest ...

. It is known from a variety of skeletal remains, rendering it a fairly common species in the area. It is a large opossum species, comparable to the modern

Virginia opossum The Virginia opossum (''Didelphis virginiana''), also known as the North American opossum, is the only opossum living north of Mexico, its range extending south into Central America. It is the northernmost marsupial in the world. In the United S ...

in size. * ''Thylophorops lorenzinii'': Currently known only from the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

MLP 08-III-10-1, a lower jaw and skull fragment, coming from Late

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Buenos Aires Buenos Aires ( or ; ), officially the Autonomous City of Buenos Aires ( es, link=no, Ciudad Autónoma de Buenos Aires), is the capital and primate city of Argentina. The city is located on the western shore of the Río de la Plata, on South ...

. It represents a juvenile individual, estimated to weight around , making it the largest known didelphid of all time. * ''Thylophorops perplana/perplanus'': The earliest known species, occurring in Early Pliocene Argentinian deposits.Goin, Francisco J.; Ulyses F. J. Pardinas (1996). "Revision de las especies del genero Hyperdidelphys Ameghino, 1904 (Mammalia, Marsupialia, Didelphidae. Su significacion filogenetica, estratigrafica y adaptativa en el Neogeno del Cono Sur sudamericano". Estudios Geológicos. 52 (5–6): 327–359. doi:10.3989/egeol.96525-6275.

Biology

''Thylophorops'' species (as well as several other contemporary opossum genera) show a high degree of speciation towards carnivory compared to most living didelphines. Their premolar and molar teeth were proportionally larger than those of living opossums and their grinding facets imply a more dedicated shearing action; these have been interpreted as "omnivory leading towards carnivory" and as more specialized carnivory in posterior studies. There is evidence that ''T. chapadmalensis'' re-appropriated burrows from other digging mammals, as well as outright consuming them. ''Thylophorops'' species as a whole tended to be terrestrial rather than arboreal.

Paleoecology

''Thylophorops'' lived at a time when South America's older predatory guilds were dismantling. It co-existed with only a few sparassodont and phorusrhacid taxa like '' Thylacosmilus'' and '' Llallawavis'', and it, as well as similar opossum species, evolved to fill the ecological blanks. A similar case is observed with the carnivorous

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, alo ...

Macroeuphractus ''Macroeuphractus'' is a genus of extinct armadillos from the Late Miocene to Late Pliocene of South America. The genus is noted for its large size, with ''Macroeuphractus outesi'' being the largest non- pampathere or glyptodont armadillo discov ...

'', a product of this same era of faunal turn-overs. As mentioned above, there is evidence of ''T. chapadmalensis'' predating on contemporary

caviomorph Caviomorpha is the rodent infraorder or parvorder that unites all New World hystricognaths. It is supported by both fossil and molecular evidence. The Caviomorpha was for a time considered to be a separate order outside the Rodentia, but is ...

s and appropriating burrows, from them or other mammals such as

armadillos 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 ...

References

{{Taxonbar, from=Q3805941 †Thylophorops Pliocene mammals of South America Prehistoric marsupial genera Chapadmalalan Huayquerian Uquian Neogene Argentina Fossils of Argentina Fossil taxa described in 1908 Taxa named by Florentino Ameghino