''Dissacus'' is a genus of extinct

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

jackal Jackals are medium-sized canids native to Africa and Eurasia. While the word "jackal" has historically been used for many canines of the subtribe canina, in modern use it most commonly refers to three species: the closely related black-backed ...

coyote The coyote (''Canis latrans'') is a species of canis, canine native to North America. It is smaller than its close relative, the wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecologica ...

-sized

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

s within the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Mesonychidae Mesonychidae (meaning "middle claws") is an extinct family of small to large-sized omnivorous-carnivorous mammals. They were endemic to North America and Eurasia during the Early Paleocene to the Early Oligocene, and were the earliest group of la ...

, an early group of hoofed mammals that evolved into hunters and

omnivores An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutri ...

. Their fossils are found in

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...

to Early

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

aged strata in

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

and southwest

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

, from 66 to 50.3 mya, existing for approximately . Orientation patch analysis of the molar teeth of the North American ''D. praenuntius'' suggests it was an omnivore that ate a lot of meat, not an exclusive meat-eater like a cat or weasel. It shared its environment with more omnivorous mammals of a similar body size. Though they are not ancestral to

Carnivora Carnivora is a Clade, monophyletic order of Placentalia, placental mammals consisting of the most recent common ancestor of all felidae, cat-like and canidae, dog-like animals, and all descendants of that ancestor. Members of this group are f ...

, ''Dissacus'' species may have had similar roles in Paleocene-early Eocene environments as the foxes and other small

canids Canidae (; from Latin, ''canis'', " dog") is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (). There are three subfamilies found within ...

that evolved later: generalized hunters who also ate fruit or other foods, and caught small animals that lived on the ground. The bear-sized ''

Ankalagon ''Ankalagon saurognathus'' is an extinct carnivorous mammal of the family Mesonychidae, endemic to North America during the Paleocene epoch (63.3—60.2 mya), existing for approximately . Known from the Paleocene Nacimiento Formation of New ...

'' is closely related to ''Dissacus''. Some paleontologists consider it a sister or daughter genus, while others suggest ''Ankalagon'' is just larger species of ''Dissacus,'' and that ''Dissacus'' is

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

. ''Dissacus'' species lived across the Northern hemisphere, a

Holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical region ...

distribution. ''Dissacus europaeus'' may have evolved in North America and migrated to Europe, and first appears in European strata in the Thanetian (circa 57-58 MYA). A phylogenetic analysis of European mesonychids suggests that ''Dissacus'' was part of an early diversification of species in the Paleocene, and other genera diversified in a later episode in the early Eocene. ''D. europaeus'' survived the Paleocene-Eocene Thermal Maximum, a period of severe global warming, which suggests it had flexible habits. Its distribution in Europe over time suggests it may have been unable to expand into areas occupied by ''

Pachyaena ''Pachyaena'' (literally, "thick hyena") was a genus of heavily built, relatively short-legged mesonychids, early Cenozoic mammals that evolved before the origin of either modern hoofed animals or carnivores, and combined characteristics similar ...

,'' which may mean it filled a similar ecological role. However, fossil records are still too incomplete for any conclusion. The fossil record of ''D. europaeus'' is fragmentary; remains in Cernay, France, include a mandible, a complete radius, and fragments of a humerus. A morphological study of these bones suggests this animal was digitigrade and more

cursorial A cursorial organism is one that is adapted specifically to run. An animal can be considered cursorial if it has the ability to run fast (e.g. cheetah) or if it can keep a constant speed for a long distance (high endurance). "Cursorial" is often u ...

than is usually assumed for the genus. Analysis of the elbow joint shows it was specialized for extra flexion and extension, an adaptation usually found in running species; the amount of specialization is unusual for a Paleocene mammal. This does not mean ''Dissacus'' species were swift runners by modern standards, but that ''D. europaeus'' was more adapted for running than other mammals of its time. It may be part of a trend among early Cenozoic mammals toward developing more specialized bodies to fill different ecological niches.

Species

*Genus ''Dissacus'' **'' Dissacus argenteus'' **'' Dissacus europaeus'' **'' Dissacus indigenus'' **'' Dissacus magushanensis'' **'' Dissacus navajovius'' **''

Dissacus praenuntius ''Dissacus'' is a genus of extinct carnivorous jackal to coyote-sized mammals within the family Mesonychidae, an early group of hoofed mammals that evolved into hunters and omnivores. Their fossils are found in Paleocene to Early Eocene aged s ...

'' **'' Dissacus raslanloubatieri'' **'' Dissacus rotundus'' **'' Dissacus rougierae'' **'' Dissacus serior'' **'' Dissacus serratus'' **'' Dissacus willwoodensis'' **''

Dissacus zanabazari ''Dissacus'' is a genus of extinct carnivorous jackal to coyote-sized mammals within the family Mesonychidae, an early group of hoofed mammals that evolved into hunters and omnivores. Their fossils are found in Paleocene to Early Eocene aged s ...

'' **''

Dissacus zengi ''Dissacus'' is a genus of extinct carnivorous jackal to coyote-sized mammals within the family Mesonychidae, an early group of hoofed mammals that evolved into hunters and omnivores. Their fossils are found in Paleocene to Early Eocene aged stra ...

References

Fossils of France Fossils of China Mesonychids Paleocene mammals Eocene mammals Eocene genus extinctions Danian first appearances Fossil taxa described in 1881 Prehistoric placental genera {{paleo-mammal-stub