''Cronopio'' 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 ...

of small insectivorous mammal known from the early Late Cretaceous of the Río Negro region 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 ...

. Its only species is ''Cronopio dentiacutus''.supplementary information
It belongs to the

Meridiolestida Meridiolestida is an extinct clade of mammals known from the Cretaceous and Cenozoic of South America and possibly Antarctica. They represented the dominant group of mammals in South America during the Late Cretaceous. Meridiolestidans were morph ...

, an extinct group of mammals widespread in South America during the Late Cretaceous, which are more closely related to modern

marsupial Marsupials are a diverse group of mammals belonging to the infraclass Marsupialia. They are natively found in Australasia, Wallacea, and the Americas. One of marsupials' unique features is their reproductive strategy: the young are born in a r ...

s and

placental mammals Placental mammals ( infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguish ...

than to

monotreme Monotremes () are mammals of the order Monotremata. They are the only group of living mammals that lay eggs, rather than bearing live young. The extant monotreme species are the platypus and the four species of echidnas. Monotremes are typified ...

Description

''Cronopio'' is known 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 ...

MPCA PV 454, a partial

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

around long which is missing the skull roof, basicranium and squamosals and from the referred specimens MPCA PV 450, a partial left

lower jaw In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

with damaged teeth and MPCA PV 453, an incomplete skull with a relatively complete right lower jaw missing some teeth. All specimens were collected in La Buitrera locality, from the

Candeleros Formation The Candeleros Formation is a geologic formation that outcrop, crops out in the Rio Negro Province, Río Negro, Neuquen Province, Neuquén, and Mendoza Province, Mendoza provinces of northern Patagonia, Argentina. It is the oldest formation in the ...

of the

Neuquén Group The Neuquén Group is a geologic unit, group of geologic formations found in Argentina. Rocks in the Neuquén Group fall within the Cenomanian to early Campanian stages of the Late Cretaceous Period. It overlies the older Lohan Cura Formation and ...

, dating to the early

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

stage of the early

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

, about 99.6-96

million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...

. Paleontologist Guillermo Rougier commented on the creature's "superficial" resemblance to the fictional character

Scrat Scrat is a fictional rodent in the Ice Age (franchise), ''Ice Age'' franchise and the mascot of the now-defunct animation company Blue Sky Studios. In the 2002 film ''Ice Age (2002 film), Ice Age'' plus its follow-up shorts and theatrical seque ...

in the '' Ice Age franchise'' created by

Chris Wedge John Christian Wedge (born March 20, 1957) is an American filmmaker, animator, and voice actor. He is best known for being the lead animator of the sci-fi action film ''Tron'' (1982), co-founding the now defunct animation studio Blue Sky Studios ...

, saying "it just goes to show how diverse ancient mammals are, that we can just imagine some bizarre critter and later find something just like it."

Etymology

''Cronopio'' was first named by Guillermo W. Rougier, Sebastián Apesteguía and Leandro C. Gaetano in

2011 The year marked the start of a Arab Spring, series of protests and revolutions throughout the Arab world advocating for democracy, reform, and economic recovery, later leading to the depositions of world leaders in Tunisia, Egypt, and Yemen ...

and the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

is ''C. dentiacutus''. The generic name is named after the

fictional characters In fiction, a character is a person or being in a narrative (such as a novel, play, radio or television series, music, film, or video game). The character may be entirely fictional or based on a real-life person, in which case the distinction o ...

appearing in the work of Argentinian writer

Julio Cortázar Julio Florencio Cortázar (26 August 1914 – 12 February 1984; ) was an Argentine and naturalised French novelist, short story writer, poet, essayist, and translator. Known as one of the founders of the Latin American Boom, Cortázar influenc ...

. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

is derived from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

, meaning "sharp-toothed".

Phylogeny

Cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

following the analysis of Rougier, Wible, Beck and Apesteguía (2012):

References

{{Taxonbar, from1=Q16014290, from2=Q134994 Meridiolestida Cenomanian life Late Cretaceous mammals of South America Cretaceous Argentina Fossils of Argentina Candeleros Formation Fossil taxa described in 2011