''Cachiyacuy'' 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 ...

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 ...

known from the Loreto of

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

. It contains two species: the type species ''C. contamanensis'' and ''C. kummeli''.

Description

All ''Cachiyacuy'' specimens were collected in the CTA-27 Locality (or Maquía locality), from the uppermost part of the Yahuarango Formation, dating to the latest

Lutetian The Lutetian is, in the geologic timescale, a stage (stratigraphy), stage or age (geology), age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it ...

stage of the late

Middle Eocene The Eocene ( ) is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''Ēṓs'', ' Dawn') a ...

, about 41

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 ...

. The type species ''C. contamanensis'' 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 ...

MUSM 1871, a right second molar and from some referred teeth including MUSM 1870, MUSM 1872, MUSM 1873, MUSM 1874, MUSM 1875, MUSM 1876, MUSM 1877, MUSM 1878, MUSM 1879 and MUSM 1880. Its body mass estimated at 80–120

gram The gram (originally gramme; SI unit symbol g) is a Physical unit, unit of mass in the International System of Units (SI) equal to one thousandth of a kilogram. Originally defined in 1795 as "the absolute Mass versus weight, weight of a volume ...

. The second species ''Cachiyacuy kummeli'' is known from the

MUSM 1882, a left first molar and from some referred teeth including MUSM 1881, MUSM 1883, MUSM 1885, MUSM 1886, MUSM 1887 and MUSM 1888. It was a tiny rodent, approximately 30% smaller than ''C. contamanensis'' as its body mass estimated at 30–40 gram. A

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

analysis found ''Cachiyacuy'' to be monophyletic and one of the

basalmost In phylogenetics, basal is the direction of the ''base'' (or root) of a rooted phylogenetic tree or cladogram. The term may be more strictly applied only to nodes adjacent to the root, or more loosely applied to nodes regarded as being close to th ...

and the oldest known caviomorph (the other being '' Canaanimys'' from the same locality).

Etymology

''Cachiyacuy'' was first named by Pierre-Olivier Antoine, Laurent Marivaux, Darin A. Croft, Guillaume Billet, Morgan Ganerød, Carlos Jaramillo, Thomas Martin, Maëva J. Orliac, Julia Tejada, Ali J. Altamirano, Francis Duranthon, Grégory Fanjat, Sonia Rousse and Rodolfo Salas Gismondi in

2012 2012 was designated as: *International Year of Cooperatives *International Year of Sustainable Energy for All Events January *January 4 – The Cicada 3301 internet hunt begins. * January 12 – Peaceful protests begin in the R ...

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 ''Cachiyacuy contamanensis''. The generic name is derived from ''Cachiyacu'', name of a local River, and ''cuy'',

Quechua Quechua may refer to: *Quechua people, several Indigenous ethnic groups in South America, especially in Peru *Quechuan languages, an Indigenous South American language family spoken primarily in the Andes, derived from a common ancestral language ...

for "guinea pig". 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 ...

of the type species is named after the geographical provenance of the specimens, close to the city of

Contamana Contamana is a town in the Loreto Region in northeastern Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bo ...

. The specific name of ''C. kummeli'' honors the

geologist A geologist is a scientist who studies the structure, composition, and History of Earth, history of Earth. Geologists incorporate techniques from physics, chemistry, biology, mathematics, and geography to perform research in the Field research, ...

Bernhard for describing extensively for the first time the Cachiyacu section in the 1940s.

References

{{Taxonbar, from=Q1949631 Hystricognath rodents Eocene rodents Eocene mammals of South America Divisaderan Paleogene Peru Fossils of Peru Fossil taxa described in 2012