Temporal range: Late Cretaceous - Eocene, 66–50 Ma
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Arctocyon
Scientific classification
Domain:
Eukaryota
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Order:
†Arctocyonia
Family:
†Arctocyonidae Giebel, 1855[1]
Subfamilies and genera
†Karakia Thewissen, Williams & Hussain, 1977
†Loxolophinae Van Valen, 1978
†Platymastus Van Valen, 1978
†Desmatoclaenus Gazin, 1941
†Baioconodon Gazin, 1941
†Loxolophus Cope, 1885
†Mimotricentes Simpson, 1937
†Deuterogonodon Simpson, 1935
†Arctocyoninae Giebel, 1855
†Neoclaenodon Gidley, 1919
†Claenodon Scott, 1892
†Colpoclaenus Patterson & McGrew, 1962
†Mentoclaenodon Weigelt, 1960
†Arctocyonides Lemoine, 1891
†Landenodon Quinet, 1968
†Arctocyon de Blainville, 1841
†Anacodon Cope, 1882
Arctocyonidae (from Greek arktos and kyôn, "bear/dog-like") is as an extinct family of unspecialized, primitive mammals with more than 20 genera. Animals assigned to this family were most abundant during the Paleocene, but extant from the late Cretaceous to the early Eocene (66 to 50 million years ago).[2]
Like most early mammals, their actual relationships are very difficult to resolve. No Paleocene fossil has been unambiguously assigned to any living order of placental mammals, and many genera resemble each other: generalized robust, not very agile animals with long tails and all-purpose chewing teeth, living in warm closed-canopy forests with many niches left vacant by the K-T extinction.[3]
Arctocyonids were early defined as a family of creodonts (early predators), then reassigned to the condylarths (primitive plant-eaters, now understood as a wastebasket taxon). More recently, these animals have been thought to be the ancestors of the orders Mesonychia and Cetartiodactyla, although some morphological studies have suggested that Arctocyonidae is also a wastebasket taxon for basal ungulates, and is in fact polyphyletic.[4]
As of 2015, the largest cladistic study of Paleocene mammals to date supports the idea that the animals in this group are not related, with Arctocyon and Loxolophus sister to pantodonts+periptychids, Goniacodon and Eoconodon sister to carnivores+mesonychids, most other genera allied with creodonts and palaeoryctidans, and Protungulatum not a placental mammal at all.[5] If this analysis holds true, then any "Arctocyonid" characteristics are the result of coincidence (selection by the observer of characteristics shared by many early Tertiary mammals) or convergence (similar habits in life).
^Peter E. Kondrashov, Spencer G. Lucas (2004). "Oxyclaenus from the Early Paleocene of New Mexico and the status of the Oxyclaeninae (Mammalia, Arctocyonidae)". New Mexico Museum of Natural History and Science Bulletin. 26: 21.
^Allaby, Michael (2003). A dictionary of zoology (2nd ed.). Oxford University Press. p. 42. ISBN 978-0-19-860758-8.
^Shelley, Sarah Laura (2018-07-03). "Rise of placental mammals: the anatomy, palaeobiology and phylogeny of Periptychus and the Periptychidae". Brusatte, Stephen, Kroon, Dick, Natural Environment Research Council (NERC). hdl:1842/29539. {{cite journal}}: Cite journal requires |journal= (help)
^De Bast, Eric; Smith, Thierry (2013). "Reassessment of the small 'arctocyonid' Prolatidens waudruae from the early Paleocene of Belgium, and its phylogenetic relationships with ungulate-like mammals". Journal of Vertebrate Paleontology. 33 (4): 964–976. doi:10.1080/02724634.2013.747531. S2CID 86402154.
^Halliday, Thomas J.D.; Upchurch, Paul; Goswami, Anjali (2015). "Resolving the relationships of Paleocene placental mammals" (PDF). Biological Reviews. 92 (1): 521–55. doi:10.1111/brv.12242. PMC 6849585. PMID 28075073. Archived (PDF) from the original on December 23, 2022.
Arctocyonidae (from Greek arktos and kyôn, "bear/dog-like") is as an extinct family of unspecialized, primitive mammals with more than 20 genera. Animals...
A. crassum. It was formerly placed in the families Mesonychidae or Arctocyonidae, but is now the sole member of a distinct family, Andrewsarchidae. Only...
been found in Germany. Arctocyon is the eponymous genus of the family Arctocyonidae, a group of archaic mammals with uncertain affinities, once classified...
members of Ferae. There are three families classified in the order: Arctocyonidae, Oxyclaenidae, and Quettacyonidae. McKenna, M. C. (1975). "Toward a...
and jaw adaptations for greater bite force. Like the Paleocene family Arctocyonidae, mesonychids were once viewed as primitive carnivorans, and the diet...
placement of Protungulatum. This genus was initially assigned to the family Arctocyonidae, in order Condylarthra, (a group of archaic "ungulates", that is now...
difficult time reducing meat. Likewise, neither members of Oxyclaenidae nor Arctocyonidae had carnassial teeth. On the other hand, carnivorous marsupials have...
artiodactyls were thought to have evolved from a small group of condylarths, Arctocyonidae, which were unspecialized, superficially raccoon-like to bear-like omnivores...
expanded the term to include families Miacidae (including Viverravidae), Arctocyonidae, Leptictidae (now Pseudorhyncocyonidae), Oxyaenidae, Ambloctonidae and...
uncertain affiliation discovered in 1987 Princetonia (mammal), a fossil Arctocyonidae mammal genus discovered in 1989 This disambiguation page lists articles...
extinct groups of mammals, including Mesonychia and Dinocerata. Family Arctocyonidae (possibly polyphyletic assemblage) Genus Arctocyon Genus Chriacus Family...
Mirorder Eparctocyona Order †Procreodi Family †Oxyclaenidae Family †Arctocyonidae Order †Condylarthra Family †Hyopsodontidae Family †Mioclaenidae Family...
ungulate-like mammals not necessarily closely related. Paleocene–Eocene Family Arctocyonidae Genus Arctocyon Genus Chriacus Family Periptychidae Genus Ectoconus...
of characteristics that could unite Tillodontia with Pantodonta and Arctocyonidae, probable adaptations to terrestrial lifestyle, and a relatively small...
Paleocene (early Puercan) Fort Union Formation United States A member of Arctocyonidae. The type species is Sigynorum magnadivisus. Sinclairella simplicidens...
Hooker Early Eocene Blackheath Formation United Kingdom A member of Arctocyonidae. Arvernoceros insolitus Valid Vekua Bendukidze Kiladze Early Pleistocene...
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