| Miacis | |
|---|---|
 | |
| skull ofMiacis parvivorus | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Clade: | Carnivoramorpha |
| Clade: | Carnivoraformes |
| Genus: | †Miacis Cope, 1872 |
| Type species | |
| †Miacis parvivorus Cope, 1872 | |
| Synonyms | |
Miacis ("small point") is anextinctgenus of placental mammals from cladeCarnivoraformes, that lived inNorth America from the early to middleEocene.[4][5][6]
Miacis was five-clawed, about the size of aweasel (~30 cm), and lived on the North American continent. It retained some primitive characteristics such as a low skull, a long slender body, a long tail, and short legs.Miacis retained 44 teeth, although some reductions in this number were apparently in progress and some of the teeth were reduced in size.
The hind limbs were longer than the forelimbs, thepelvis was dog-like in form and structure, and some specialized traits were present in the vertebrae. It had retractable claws, agile joints for climbing, andbinocular vision.Miacis and related forms had brains that were relatively larger than those of thecreodonts, and the larger brain size as compared with body size probably reflects an increase in intelligence.[citation needed]
Like many other early carnivoramorphans, it was well suited for an arboreal climbing lifestyle with needle-sharp claws, limbs, and joints resembling modern carnivorans.Miacis was probably a very agile forest dweller thatpreyed upon smaller animals, such as smallmammals,reptiles, andbirds, and might also have eaten eggs and fruits.[7]
| Species: | Distribution of the species and type locality: | Age: |
|---|---|---|
| †M. parvivorus(Cope, 1872)[8] |  USA | 50,0 to 46,2 Ma |
SinceEdward Drinker Cope first described the genusMiacis in 1872, at least twenty other species have been assigned toMiacis. However, these species share fewsynapomorphies other thanplesiomorphic characteristics of miacids in general. This reflects the fact thatMiacis has been treated as a wastebasket taxon and contains a diverse collection of species that belong to the stemgroup within the Carnivoraformes.[6] Many of the species originally assigned toMiacis have since been assigned to other genera and, apart from the type species,Miacis parvivorus, the remaining species are often referred to withMiacis in quotations (e.g."Miacis" latidens). The following table lists the formerMiacis species in chronological order of their original description and notes the reassignments to other genera.
| Species: | Type locality: | Status and notes: |
|---|---|---|
| M. sylvestris(Marsh, 1872)[12] | Bridger Formation (Wyoming, USA) | now assigned to genusHarpalodon asHarpalodon sylvestris[13][14] |
| M. vulpinus(Scott & Osborn, 1887)[15] | Uinta Basin (Utah, USA) | Described asAmphicyon vulpinum; later assigned toProdaphaenus andMiacis;[16] now recognised as synonym ofMiocyon scotti |
| M. uintensis(Osborn, 1895)[17] | Uinta Basin (Utah, USA) | now assigned to genusProdaphaenus asProdaphaenus uintensis[10] |
| M. hargeri(Wortman, 1901)[13] | Bridger Formation (Wyoming, USA) | recognised as close relative to genusLycarion |
| M. washakius(Wortman, 1901)[13] | Bridger Formation (Wyoming, USA) | now assigned to genusNeovulpavus asNeovulpavus washakius[14] |
| M. medius(Matthew, 1909)[16] | Bridger Formation (Wyoming, USA) | now assigned to genusLycarion asLycarion medius[14] |
| M. exiguus(Matthew & Granger, 1915)[18] | Clark's Fork Basin (Wyoming, USA) | recognised as close relative to genusDormaalocyon |
| M. latidens(Matthew & Granger, 1915)[18] | Clark's Fork Basin (Wyoming, USA) | classified as a species of carnivoraform mammals outside of genusMiacis |
| M. invictus(Matthew & Granger, 1925)[19] | Irdin Manha Formation (Inner Mongolia,China) | classified as a species of carnivoraform mammals outside of genusMiacis |
| M. hookwayi(Stock, 1934)[20] | Tapo Canyon (California, USA) | classified as a species of carnivoraform mammals outside of genusMiacis |
| M. gracilis(Clark, 1939)[21] | Uinta Basin (Utah, USA) | classified as a species of carnivoraform mammals outside of genusMiacis |
| M. latouri(Quinet, 1966)[22] | Dormaal (Flemish Brabant,Belgium) | now assigned to genusDormaalocyon asDormaalocyon latouri[23] |
| M. lushiensis(Chow, 1975)[24] | Shanghuang Quarry (Jiangsu, China) | classified as a species of carnivoraform mammals outside of genusMiacis |
| M. deutschi(Gingerich, 1983)[25] | Clark's Fork Basin (Wyoming, USA) | classified as a species of carnivoraform mammals outside of genusMiacis |
| M. petilus(Gingerich, 1983)[25] | Clark's Fork Basin (Wyoming, USA) | classified as a species of carnivoraform mammals outside of genusMiacis |
| M. winkleri(Gingerich, 1983)[25] | Clark's Fork Basin (Wyoming, USA) | now assigned to genusGracilocyon as type speciesGracilocyon winkleri[26] |
| M. australis(Gustafson, 1986)[27] | Rifle Range Hollow or Blue Cliff Horizon (Texas, USA) | now assigned to genusAngelarctocyon asAngelarctocyon australis in familyAmphicyonidae[28] |
| M. cognitusGustafson, 1986[27] | Reeves Bonebed (Texas, USA) | now assigned to genusGustafsonia asGustafsonia cognita in family Amphicyonidae[28] |
| M. thailandicus(Ducrocqet al., 1992)[29] | Krabi (SouthThailand) | now assigned to genusXinyuictis asXinyuictis thailandicus |
| M. boqinghensis(Huanget al., 1999)[30] | Huoshipo, Guojiazhuang Village, Hedi Formation (China) | classified as a species of carnivoraform mammals outside of genusMiacis |
| M. rosei(Heinrichet al., 2008)[1] | Wyoming, USA | now assigned to genusGracilocyon asGracilocyon rosei[26] |
| M. rundlei(Hooker, 2010)[31] | Abbey Wood,England,UK | now assigned to genusGracilocyon asGracilocyon rundlei[23] |
| M. solei(Smith & Smith, 2010)[26] | Dormaal (Flemish Brabant, Belgium) | now assigned to genusGracilocyon asGracilocyon solei[26] |
The phylogenetic relationships of genusMiacis are shown in the following cladogram:[32][23][33][14]
| Carnivoramorpha |
| †Gracilocyon/Oodectes clade †Vulpavus clade | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
(Carnivora [sensu lato]) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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