''Notiolofos'' is an extinct genus of sparnotheriodontid

ungulate Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, cam ...

from the order

Litopterna Litopterna (from grc, λῑτή πτέρνα "smooth heel") is an extinct order of fossil hoofed mammals from the Cenozoic era. The order is one of the five great orders of South American ungulates that were endemic to the continent, until the G ...

. The animal lived during the

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' ...

, in modern-day

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...

. The

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 ...

contains two

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

, ''N. arquinotiensis'', the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

, and ''N. regueroi''.

Description

''Notiolofos'' was originally named in 2006 by Bond ''et al.'', as '' Notolophus arquinotiensis'', on the basis of a few

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

. However, after the genus was named, it became clear that the name ''Notolophus'' was already in use by a genus of

moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...

s, and the genus name was subsequently changed to ''Notiolofos'' by Bond ''et al.'' in 2009. The second species in the genus, ''Notiolofos regueroi'', was named in 2017 by Gelfo, Lopéz & Santillana, based on a single fossil molar. Fossils of ''N. arquinotiensis'' have been found in multiple layers of the

La Meseta Formation The La Meseta Formation is a sedimentary sequence deposited during the Eocene. The formation is found on Seymour Island, Antarctica. Description La Meseta Formation lies unconformably on the Cretaceous Lopez de Bertodano Formation. It is an app ...

Seymour Island Seymour Island or Marambio Island, is an island in the chain of 16 major islands around the tip of the Graham Land on the Antarctic Peninsula. Graham Land is the closest part of Antarctica to South America. It lies within the section of the isla ...

, Antarctica, and are dated from 55 to 34 million years ago. However, ''N. regueroi'' is only known from the Cucullaea I layer from the Upper Ypresian, dating to 53 million years ago. When ''Notiolofos'' lived, Antarctica was still connected to

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 ...

by a land bridge, as a remainder of the supercontinent Gondwana. ''N. regueroi'' was around the size of a

sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated s ...

, with an estimated weight of 25 to 57 kilogrammes. ''N. arquinotiensis'' was much larger, with an estimated weight of 400 kilogrammes, around the size of a muskox. It is thought to have been a browser.

Taxonomy

''Notiolofos'' is a part of the family Sparnotheriodontidae, and is most closely related to ''Victorlemoinea'', fossils of which have been found in the Upper Paleocene and Lower Eocene of Patagonia and the Brazilian Itaboraí basin.

References

{{taxonbar, from=Q42268926 Sparnotheriodontids Eocene mammals of South America Ypresian Priabonian Fossils of Antarctica Prehistoric placental genera Fossil taxa described in 2009 Prehistoric vertebrates of Antarctica