Borhyaenidae is an extinct

metatheria Metatheria is a mammalian clade that includes all mammals more closely related to marsupials than to placentals. First proposed by Thomas Henry Huxley in 1880, it is a more inclusive group than the marsupials; it contains all marsupials as wel ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of low-slung, heavily built predatory

mammals A mammal () is a vertebrate animal of the class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle e ...

in the order

Sparassodonta Sparassodonta (from Ancient Greek, Greek to tear, rend; and , gen.

, ' The comma is a punctuation mark that appears in several variants in different languages. Some typefaces render it as a small line, slightly curved or straight, but inclined from the vertical; others give it the appearance of a miniature fille ...

tooth) is an extinct order (biology), order of carnivore, carnivorous metatherian mammals native to South America, related to modern marsupials. They were once cons ...

. Borhyaenids are not true

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, but members of a

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

, Sparassodonta. Like most metatherians, borhyaenids and other sparassodonts are thought to have had a pouch to carry their offspring around. Borhyaenids had strong and powerful jaws, like those of the unrelated

placentalia 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 distingui ...

ns ''

Hyaenodon ''Hyaenodon'' ("hyena-tooth") is an Extinction (biology), extinct genus of Carnivore, carnivorous Placentalia, placental mammals from extinct tribe Hyaenodontini within extinct subfamily Hyaenodontinae (in extinct Family (biology), family Hyaenod ...

'' and ''

Andrewsarchus ''Andrewsarchus'' (), meaning "Roy Chapman Andrews, Andrews' ruler", is an extinct genus of artiodactyl that lived during the Eocene, Middle Eocene in what is now China. The genus was species description, first described by Henry Fairfield Osb ...

'', for crushing

bones A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, an ...

. Borhyaenids grew up to an average of long. Originally, the borhyaenids were considered one of the most diverse groups of sparassodonts, including all species not originally included in the

Thylacosmilidae Thylacosmilidae is an extinct family of metatherian predators, related to the modern marsupials, which lived in South America between the Miocene and Pliocene epochs. Like other South American mammalian predators that lived prior to the Great Ame ...

. However, in recent years, with the elevation of most sparassodont subfamilies to family rank and the discovery that borhyaenids are more closely related to proborhyaenids and thylacosmilids than other sparassodonts, the family has been reduced to seven species in four genera. The most studied borhyaenids are the

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

, particularly from

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 preserve ...

sites in the southernmost part of

Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...

. One species, ''Australohyaena antiqua'', is known from the

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 ...

(

Deseadan The Deseadan () age is a period of geologic time (29.0–21.0 Ma) within the Oligocene epoch of the Paleogene to the Early Miocene epoch of the Neogene, used more specifically within the SALMA classification of South America. It follows the Tingu ...

); although some Oligocene basal borhyaenoids were once considered to be borhyaenids, all other unambiguous members of the group are now considered to be restricted to 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 ...

. The fossil record of this group after the Early Miocene is poor, and only fragmentary remains attest to their presence in the

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...

. However, the only confidently identified Late Miocene borhyaenid specimen, ''Stylocynus paranensis'', comes from a site which is known to have Early Miocene fossils mixed in with Late Miocene ones, and so it may be that this group did not survive the end of the Early Miocene.

Classification

* †Family Borhyaenidae ** †Genus '' Arctodictis'' *** †''Arctodictis munizi'' *** †''Arctodictis sinclairi'' ** †Genus '' Acrocyon'' *** †'' Acrocyon riggsi'' *** †''Acrocyon sectorius'' ** †Genus '' Australohyaena'' *** †''Australohyaena antiqua'' ** †Genus '' Borhyaena'' *** †''Borhyaena tuberata'' *** †''Borhyaena macrodonta'' ** †Genus ?'' Eutemnodus''

References

Borhyaenidae - Encyclopædia Britannica
Sparassodonta Eocene first appearances Miocene extinctions Prehistoric mammal families {{paleo-mammal-stub