''Thylophorops'' is an extinct genus of didelphine opossums from the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

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

Didelphis ''Didelphis'' is a genus of New World marsupials. The six species in the genus ''Didelphis'', commonly known as Large American opossums, are members of the ''opossum'' order (biology), order, Didelphimorphia. The genus ''Didelphis'' is composed ...

'' (and like the still living '' Lutreolina'') 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 nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...

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

'', '' Philander'' and '' Lutreolina'' 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 (geology), epoch in the geologic time scale that extends from 5.33 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 ...

) Chapadmalal Formation and other (up to

Uquian The Uquian age is a period of geologic time (3.0–1.5 Ma) within the Pliocene and Pleistocene epochs of the Neogene used more specifically with South American Land Mammal Ages. It follows the Montehermosan The Montehermosan age is a period of ...

) formations in

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 ...

. 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 a member of the opossum family found from southern Canada to northern Costa Rica, making it the northernmost marsupial in the world and the only marsup ...

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

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

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

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Buenos Aires Buenos Aires, controlled by the government of the Autonomous City of Buenos Aires, is the Capital city, capital and largest city of Argentina. It is located on the southwest of the Río de la Plata. Buenos Aires is classified as an Alpha− glob ...

. 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 () 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 ...

'' Macroeuphractus'', 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 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 now accepted as ...

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

References

{{Taxonbar, from=Q3805941 †Thylophorops Pliocene mammals of South America Prehistoric marsupial genera Extinct marsupials of South America Chapadmalalan Huayquerian Uquian Neogene Argentina Fossils of Argentina Fossil taxa described in 1952 Taxa named by Osvaldo Reig