Mesonychidae
Encyclopedia
Mesonychidae is an extinct family
of medium to large-sized omnivorous-carnivorous
mammals closely related to artiodactyls (even-toed ungulates) which were endemic to North America
and Eurasia
during the Early Paleocene to Late Eocene living from 65—33.9 mya, existing for approximately .
s with a specialized dentition featuring tri-cuspid upper molars and high-crowned lower molars with shearing surfaces. They were once viewed as primitive carnivores, like the Paleocene family Arctocyonidae
, and their diet probably included meat and fish. In contrast to this other family of early mammals, the mesonychids had only four digits furnished with hooves supported by narrow fissured end phalanges.
, undergoing numerous speciation events during the Paleocene, and Eocene
. Mesonychids fared very poorly at the close of the Eocene epoch, with only one genus, Mongolestes
, surviving into the Early Oligocene
epoch.
Mesonychids probably originated in Asia
, where the most primitive mesonychid, Yangtanglestes
, is known from the early Paleocene. They were also most diverse in Asia where they occur in all major Paleocene fauna
s. Since other carnivore
s such as the creodonts and condylarth
s were either rare or absent in these animal communities, mesonychids most likely dominated the large predator niche
in the Paleocene of Asia. Throughout the Paleocene and Eocene, several genera, including Dissacus
, Pachyaena
and Mesonyx
would radiate out from their ancestral home in Asia and into Europe and North America, where they would give rise to new mesonychid genera. These animals would have migrated to North America via the Bering land bridge
.
The term "mesonychid
" is often used to refer to any of the various members of the order
Mesonychia, though most experts prefer to use it to refer to the members of the family Mesonychidae, with many experts using the term "mesonychian" to refer to the order as a whole.
by Cope (1880); to Creodonta by Cope (1889); to Carnivora
by Peterson (1919); to Mesonychia by Carroll (1988) and Zhou et al. (1995); and to Cete by Archibald (1998).
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of medium to large-sized omnivorous-carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
mammals closely related to artiodactyls (even-toed ungulates) which were endemic to North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
during the Early Paleocene to Late Eocene living from 65—33.9 mya, existing for approximately .
Description
The mesonychids were an unusual group of condylarthCondylarth
Condylarthra is an order of extinct placental mammals known primarily from the Paleocene and Eocene epochs. Condylarths are among the most characteristic Paleocene mammals and they illustrate the evolutionary level of the Paleocene mammal fauna....
s with a specialized dentition featuring tri-cuspid upper molars and high-crowned lower molars with shearing surfaces. They were once viewed as primitive carnivores, like the Paleocene family Arctocyonidae
Arctocyonidae
Arctocyonidae is an extinct family of unspecialized, primitive mammals with more than 20 genera most abundant during the Paleocene, but extant from the late Cretaceous to the early Eocene ....
, and their diet probably included meat and fish. In contrast to this other family of early mammals, the mesonychids had only four digits furnished with hooves supported by narrow fissured end phalanges.
Evolutionary history
They first appeared in the Early PaleocenePaleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
, undergoing numerous speciation events during the Paleocene, and Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
. Mesonychids fared very poorly at the close of the Eocene epoch, with only one genus, Mongolestes
Mongolestes
Mongolestes is an extinct mammal genus. Fossils have been found in the 'Ulan Gochu' formation of inner Mongolia and likely originated in Asia....
, surviving into the Early Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
epoch.
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, where the most primitive mesonychid, Yangtanglestes
Yangtanglestes
Yangtanglestes conexus is a weasel-like Chinese mesonychid with slender jaws that first appeared during the Early Paleocene and was found throughout Asia. It is the oldest known mesonychid...
, is known from the early Paleocene. They were also most diverse in Asia where they occur in all major Paleocene fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...
s. Since other carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
s such as the creodonts and condylarth
Condylarth
Condylarthra is an order of extinct placental mammals known primarily from the Paleocene and Eocene epochs. Condylarths are among the most characteristic Paleocene mammals and they illustrate the evolutionary level of the Paleocene mammal fauna....
s were either rare or absent in these animal communities, mesonychids most likely dominated the large predator niche
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...
in the Paleocene of Asia. Throughout the Paleocene and Eocene, several genera, including Dissacus
Dissacus
Dissacus is an extinct carnivorous jackal to coyote-sized mammal of the family Mesonychidae, endemic to Asia and North America during the Paleocene through Eocene epochs 65—50.3 mya, existing for approximately ....
, Pachyaena
Pachyaena
Pachyaena was a genus of heavily built, relatively short-legged mesonychids that originated from Asia. The species ranged in size from a coyote to a bear...
and Mesonyx
Mesonyx
Mesonyx was a wolf-like mammal of the family Mesonychidae, the type family of the order Mesonychia , existing 51.8—51.7 Ma . It may have been ancestral to cetaceans....
would radiate out from their ancestral home in Asia and into Europe and North America, where they would give rise to new mesonychid genera. These animals would have migrated to North America via the Bering land bridge
Bering land bridge
The Bering land bridge was a land bridge roughly 1,000 miles wide at its greatest extent, which joined present-day Alaska and eastern Siberia at various times during the Pleistocene ice ages. Like most of Siberia and all of Manchuria, Beringia was not glaciated because snowfall was extremely light...
.
The term "mesonychid
Mesonychid
Mesonychia are an extinct order of medium to large-sized carnivorous mammals that were closely related to artiodactyls and to cetaceans...
" is often used to refer to any of the various members of the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Mesonychia, though most experts prefer to use it to refer to the members of the family Mesonychidae, with many experts using the term "mesonychian" to refer to the order as a whole.
Taxonomy
Mesonychidae was named by Cope (1880). It is not extant. Its type is Mesonyx. It was assigned to CreodontaCreodonta
The creodonts are an extinct order of mammals that lived from the Paleocene to the Miocene epochs. They shared a common ancestor with the Carnivora....
by Cope (1880); to Creodonta by Cope (1889); to Carnivora
Carnivora
The diverse order Carnivora |Latin]] carō "flesh", + vorāre "to devour") includes over 260 species of placental mammals. Its members are formally referred to as carnivorans, while the word "carnivore" can refer to any meat-eating animal...
by Peterson (1919); to Mesonychia by Carroll (1988) and Zhou et al. (1995); and to Cete by Archibald (1998).
Species
Family Mesonychidae- Genus AnkalagonAnkalagonAnkalagon saurognathus is an extinct carnivorous mammal of the family Mesonychidae, endemic to North America during the Paleocene epoch , existing for approximately ....
- Ankalagon saurognathus
- Genus DissacusDissacusDissacus is an extinct carnivorous jackal to coyote-sized mammal of the family Mesonychidae, endemic to Asia and North America during the Paleocene through Eocene epochs 65—50.3 mya, existing for approximately ....
- Dissacus argenteus
- Dissacus europaeus
- Dissacus indigenus
- Dissacus magushanensis
- Dissacus navajovius
- Dissacus praenuntius
- Dissacus rotundus
- Dissacus serior
- Dissacus serratus
- Dissacus willwoodensis
- Dissacus zanabazari
- Dissacus zengi
- Genus GuilestesGuilestesGuilestes is a mesonychid that lived during the Eocene in south China.-External links:**...
- Guilestes acares
- Genus HarpagolestesHarpagolestesHarpagolestes is an extinct genus of hyena like, bear sized Mesonychidae that lived in middle and eastern Asia during the middle to late Eocene....
- Harpagolestes immanis
- Harpagolestes koreanicus
- Harpagolestes orientalis
- Genus Hessolestes
- Genus HukoutheriumHukoutheriumHukoutherium lived during the middle Pliocene in Asia and was named by Chow. It is believed by some paleontologist that Hukoutherium could be the ancestors of whales, but due to a lack of fossil evidence this remains controversy....
- Hukoutherium ambigum
- Hukoutherium shimemensis
- Genus JiangxiaJiangxiaJiangxia District is one of the administrative districts within the City of Wuhan. Jiangxia district has an area of 2,009 km² and a population of 680,000....
- Jiangxia chaotoensisJiangxia chaotoensisJiangxia chaotoensis is a Chinese mesonychid from the Nongshanian division of the Upper Paleocene. It may be related to the genera Pachyaena and Hessolestes.J. chaotoensis was named after the province of Jiangxi, where it was found....
- Jiangxia chaotoensis
- Genus MesonyxMesonyxMesonyx was a wolf-like mammal of the family Mesonychidae, the type family of the order Mesonychia , existing 51.8—51.7 Ma . It may have been ancestral to cetaceans....
- Mesonyx obtusidens
- Mesonyx uintensis
- Genus MongolestesMongolestesMongolestes is an extinct mammal genus. Fossils have been found in the 'Ulan Gochu' formation of inner Mongolia and likely originated in Asia....
- Mongolestes hadrodens
- Mongolestes huangheensis
- Genus MongolonyxMongolonyxMongolonyx is an extinct genus of carnivorous mesonychid mammal that lived during the Middle Eocene in Mongolia. It became extinct during the Oligocene. It was described by Szalay and Gould.Mongolonyx fossils have been found in the 'Irdin Manha' beds....
- Mongolonyx dolichognathus
- Mongolonyx robustus
- Genus PachyaenaPachyaenaPachyaena was a genus of heavily built, relatively short-legged mesonychids that originated from Asia. The species ranged in size from a coyote to a bear...
- Pachyaena gigantea
- Pachyaena intermedia
- Pachyaena ossifraga
- Pachyaena gracilis
- Genus SinonyxSinonyxSinonyx was a wolf-like ungulate Mesonychid mammal from the late Paleocene of China that lived about 56 million years ago. It was an early primitive form of mesonychid, which some experts regard as a distinctive group of carnivorous condylarths, which gave rise to artiodactyls. Sinonyx was...
- Sinonyx jiashanensis
- Genus SynoplotheriumSynoplotheriumSynoplotherium is an extinct genus of relatively small, wolf-like mesonychids that lived 50 million years ago, in what is now Wyoming....
- Synoplotherium vorax
- Genus YangtanglestesYangtanglestesYangtanglestes conexus is a weasel-like Chinese mesonychid with slender jaws that first appeared during the Early Paleocene and was found throughout Asia. It is the oldest known mesonychid...
- Yangtanglestes conexus