''Palaeonictis'' ("ancient weasel") is an extinct predatory mammal belonging to the family

Oxyaenidae Oxyaenidae ("sharp hyenas") is a family of extinct carnivorous placental mammals. Traditionally classified in order Creodonta, this group is now classified in its own order Oxyaenodonta ("sharp tooth hyenas") within clade Pan-Carnivora in miror ...

, existing from the late

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pal ...

to the early

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

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti ...

and North America.

Description

In life, it would have resembled a large modern

wolverine The wolverine (), (''Gulo gulo''; ''Gulo'' is Latin for " glutton"), also referred to as the glutton, carcajou, or quickhatch (from East Cree, ''kwiihkwahaacheew''), is the largest land-dwelling species of the family Mustelidae. It is a musc ...

. This oxyaenid had heavy jaws and blunt robust teeth more suited for crushing bones, than slicing meat. This meant that the plantigrade ''Palaeonictis'' was at least a part-time scavenger. The biggest species, ''Palaeonictis peloria'' (meaning "terrible ancient weasel") is known from an incomplete jaw that must have measured over in length. This animal was the largest carnivore in its ecosystem. , ''P. occidentalis'' (the size of a bear) evolved into the smaller ''P. wingi'' (the size of a coyote) within 200,000 years in the early Eocene due to global warming (

paleoclimatology Paleoclimatology (American and British English spelling differences, British spelling, palaeoclimatology) is the study of climates for which direct measurements were not taken. As instrumental records only span a tiny part of Earth's history, the ...

). By the end of the early Eocene (), ''Palaeonictis'' disappeared from North America, and by the early Eocene () the last species of ''P. gigantea'' had vanished from Europe. In fact, the entire family Oxyaenidae had become extinct worldwide (although its sister group

Hyaenodonta Hyaenodonta ("hyena teeth") is an extinct order of hypercarnivorous placental pan-carnivoran mammals from mirorder Ferae. Hyaenodonts were important mammalian predators that arose during the early Paleocene in Europe and persisted well into ...

continued to thrive for a while). This is traditionally assumed to be due to increased competition from

miacids Miacids are extinct primitive carnivoramorphans within the family Miacidae that lived during the Paleocene and Eocene epochs, about 62–34 million years ago. Miacids existed for approximately . Miacids are thought to have evolved into the ...

and nimravids belonging to the more successful order

Carnivora Carnivora is a monophyletic order of placental mammals consisting of the most recent common ancestor of all cat-like and dog-like animals, and all descendants of that ancestor. Members of this group are formally referred to as carnivorans, ...

, which eventually replaced earlier carnivorous mammal clades in the later

Neogene The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago (Mya) to the beginning of the present Quaternary Period Mya. ...

as the world's top predators, though no evidence of direct competition is known, and carnivorans may have simply filled vacated niches.

Phylogeny

The phylogenetic relationships of genus ''Palaeonictis'' are shown in the following cladogram.Prevosti, F. J. & Forasiepi, A. M. (2018.
"Introduction. Evolution of South American Mammalian Predators During the Cenozoic: Paleobiogeographic and Paleoenvironmental Contingencies"
/ref>

References

Oxyaenidae Eocene mammals of Europe Eocene mammals of North America Paleocene mammals of North America Paleocene first appearances Eocene genus extinctions Fossil taxa described in 1842 Prehistoric placental genera {{paleo-mammal-stub

Description

Phylogeny

See also

References