''Lakukullus'' is an extinct genus of nothrotheriid ground sloths that lived during the Middle Miocene around 13.8 to 11.8 million years ago of what is now Bolivia.

Etymology

The genus name, ''Lakukullus'', is composed of "Laku’kullu", which means "wild animal of heights" in

Aymara Aymara may refer to: Languages and people * Aymaran languages, the second most widespread Andean language ** Aymara language, the main language within that family ** Central Aymara, the other surviving branch of the Aymara(n) family, which today ...

, a native Bolivian language, which refers to the locality the specimen was found. The specific name is derived from the Latin word "anatisrostratum", which means "duck beak" in reference to the aspect of the snout appearing physically similar to the bill of an aquatic bird.

Classification

''Lakukullus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

from the now extinct

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Nothrotheriidae Nothrotheriidae is a family of extinct ground sloths that lived from approximately 17.5 mya—10,000 years ago, existing for approximately . Previously placed within the tribe Nothrotheriini or subfamily Nothrotheriinae within Megatheriidae, th ...

. The Nothrotheriidae are represented by rather medium-sized members of the suborder of

sloths Sloths are a group of Neotropical xenarthran mammals constituting the suborder Folivora, including the extant arboreal tree sloths and extinct terrestrial ground sloths. Noted for their slowness of movement, tree sloths spend most of their l ...

, Folivora. Their phylogenetically younger members possessed a dentition reduced by the anterior-most tooth per mandibular arch, diverging from other sloth groups.H. Gregory McDonald und Gerardo de Iuliis: ''Fossil history of sloths.'' In: Sergio F. Vizcaíno und W. J. Loughry (Hrsg.): ''The Biology of the Xenarthra.'' University Press of Florida, 2008, S. 39–55. The Nothrotheriidae, together with the

Megatheriidae Megatheriidae is a family of extinct ground sloths that lived from approximately 23 mya—11,000 years ago. Megatheriids appeared during the Late Oligocene (Deseadan in the SALMA classification), some 29 million years ago, in South America ...

and with the

Megalonychidae Megalonychidae is an extinct family of sloths including the extinct ''Megalonyx''. Megalonychids first appeared in the early Oligocene, about 35 million years (Ma) ago, in southern Argentina (Patagonia). There is actually one possible find datin ...

, form a more closely related group within the sloths, the superfamily of

Megatherioidea Sloths are a group of Neotropical xenarthran mammals constituting the suborder Folivora, including the extant arboreal tree sloths and extinct terrestrial ground sloths. Noted for their slowness of movement, tree sloths spend most of their li ...

. According to the classical view, determined by skeletal anatomy investigations, the Megatherioidea can be considered one of the two major sloth lineages, the second being represented by the

Mylodontoidea Sloths are a group of Neotropical xenarthran mammals constituting the suborder Folivora, including the extant arboreal tree sloths and extinct terrestrial ground sloths. Noted for their slowness of movement, tree sloths spend most of their l ...

. With the inclusion of

molecular genetic Molecular genetics is a sub-field of biology that addresses how differences in the structures or expression of DNA molecules manifests as variation among organisms. Molecular genetics often applies an "investigative approach" to determine the ...

and

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

-based studies, a third lineage, the Megalocnoidea, is added. According to the latter studies, the Megatherioidea also include one of the two present-day sloth genera, the

three-toed sloth The three-toed or three-fingered sloths are arboreal neotropical mammals . They are the only members of the genus ''Bradypus'' and the family Bradypodidae. The four living species of three-toed sloths are the brown-throated sloth, the maned slot ...

s of the genus ''Bradypus''.Frédéric Delsuc, Melanie Kuch, Gillian C. Gibb, Emil Karpinski, Dirk Hackenberger, Paul Szpak, Jorge G. Martínez, Jim I. Mead, H. Gregory McDonald, Ross D.E. MacPhee, Guillaume Billet, Lionel Hautier und Hendrik N. Poinar: ''Ancient mitogenomes reveal the evolutionary history and biogeography of sloths.'' Current Biology 29 (12), 2019, S. 2031–2042, doi:10.1016/j.cub.2019.05.043 Thereby, within the Megatherioidea, the Megatheriidae and the Nothrotheriidae are in a sister group relationship, but in part a closer relationship of the Nothrotheriidae with the Megalonychidae is also discussed. Overall, the Nothrotheriidae comprise only about a dozen genera, with their earliest record dating to the Middle Miocene. Two subfamilies can be distinguished within the family. ''Thalassocnus'' is generally assigned to Thalassocninae as its sole member. The other subfamily is represented by the

Nothrotheriinae Nothrotheriidae is a family of extinct ground sloths that lived from approximately 17.5 mya—10,000 years ago, existing for approximately . Previously placed within the tribe Nothrotheriini or subfamily Nothrotheriinae within Megatheriidae, th ...

, which includes, among others, the better known forms of the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

such as ''

Nothrotherium ''Nothrotherium'' is an extinct genus of medium-sized ground sloth from South America (Bolivia, Brazil and the Ware Formation, La Guajira, Colombia).Amson et al., 2016, p.12 It differs from ''Nothrotheriops'' in smaller size and differences in sk ...

'' from South America and ''

Nothrotheriops ''Nothrotheriops'' is a genus of Pleistocene ground sloth found in North America, from what is now central Mexico to the southern United States. This genus of bear-sized xenarthran was related to the much larger, and far more famous '' Megatheriu ...

'' from North America. In addition, ''Lakukullus'' is also one of the most basal known members of the subfamily Nothrotheriinae. Below is a phylogenetic tree of the Nothrotheriinae based on Varela ''et al''. 2019.

References

{{Taxonbar, from=Q112136106 Prehistoric sloths Prehistoric placental genera Miocene mammals of South America Miocene xenarthrans Neogene Bolivia Laventan Fossils of Bolivia Fossil taxa described in 2014