''Thadanius'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Litoptern Litopterna (from "smooth heel") is an extinct order of South American native ungulates that lived from the Paleocene to the Pleistocene-Holocene around 62.5 million to 12,000 years ago (or possibly as late as 3,500 years ago), and were also pres ...

, belonging to the family

Adianthidae Adianthidae is an extinct family of litopterns that existed from the Middle Eocene (Mustersan) to the Early Miocene (Santacrucian). Description Adianthids were actively mobile herbivores. They were small in size when compared to most litopterns ...

. It lived during the Late

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

, in what is today

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

Description

Only known from the fossilized remains of its mandible and teeth, this animal may have been similar to its relatives ''

Adianthus ''Adianthus'' is an extinct genus of litoptern that lived during the Early Miocene to the Middle Miocene in what is now Argentina and Chile. Description This animal is only known from fragmentary remains, mainly from its teeth, and was probably ...

'' and '' Adiantoides'', and probably was a small animal, the size of a small dog and slender in build. ''Thadanius'' was characterized by moderately high crowned teeth; the lower molars were devoid of anterior cingulum, while the hypoconulid was not expanded as in other contemporary

, such as ''

Tricoelodus ''Tricoelodus'' is an extinct genus of adianthid litopterns that lived during the Late Oligocene in what is now Argentina and Bolivia. Fossils of this genus have been found in the Sarmiento Formation of Argentina and the Salla Formation of Bol ...

'' and ''

Proadiantus ''Proadiantus'' (Ameghino, 1897) is an extinct genus of adianthid litoptern. It lived during the Late Oligocene, in what is today South America. It consists of only 1 species, ''Proadiantus excavatus.'' Description This animal is mainly known ...

'' to form a third lobe on the third molar. The entoconid did not reach the apex of the hypoconulid, but was connected to an hypoconulid-entoconid crest, and a rudimentary entolophid was present, especially on the third lower molar. There was no basin on the lower third molar.

Classification

''Thadanius'' was a member of the

, a clade of small-sized litopterns that went extinct during the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

period. ''Thadanius'' shares similarities with ''Proadiantus'', and they may have been related, as ''Tricoelodus''. ''Thadanius'' was first described in 1983, based on fragmentary remains from the

Salla Formation Salla, known as Kuolajärvi until 1936, is a municipality of Finland, located in Lapland. The municipality has a population of () and covers an area of of which is water. The population density is . The nearby settlement of Sallatunturi is ...

, in the

Loayza Province Loayza or José Ramón Loayza is a province in the La Paz Department, Bolivia. Its seat is Luribay. Geography The Kimsa Cruz mountain range traverses the province. Some of the highest mountains of the province are listed below: Subdivisio ...

, in terrains dated from the Late Oligocene. Its name is an

anagram An anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once. For example, the word ''anagram'' itself can be rearranged into the phrase "nag a ram"; which ...

of ''Adianthus'', the eponymous genus of Adianthidae.R. L. Cifelli and M. F. Soria. 1983. Systematics of the Adianthidae (Litopterna, Mammalia). American Museum Novitates 2771:1-25

References

{{Taxonbar, from=Q110465319 Litopterns Oligocene mammals of South America Paleogene Bolivia Fossils of Bolivia Fossil taxa described in 1983 Prehistoric placental genera