''Cynodesmus'' ("dog link") is an extinct genus of
omnivorous
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 ...
canine which inhabited
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 ...
during the
Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
living from 33.3—-26.3 Ma and existed for approximately .
''Cynodesmus'' was one of the first
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 ...
to truly look dog-like. At around in length, it was about the same size as a modern
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 ...
, but had a shorter
skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...
, heavier tail, and longer rump. The shape of its limbs suggests that ''Cynodesmus'' was not a very good runner compared to most other canids; it probably attacked prey from an ambush. Unlike modern dogs, it had five toes on each foot, bearing partially retractable
claw
A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus ...
s.
Taxonomy
''Cynodesmus'' once included numerous species of
Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
and
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
canid with highly carnivorous (
hypercarnivorous
A hypercarnivore is an animal which has a diet that is more than 70% meat, either via active predation or by scavenging. The remaining non-meat diet may consist of non-animal foods such as fungi, fruits or other plant material. Some extant exampl ...
)
dentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolo ...
s. A revision of the genus by Wang (1994) indicates that most species previously placed in ''Cynodesmus'' are unrelated to the type species, ''C. thooides''. These other species have been placed the genera ''
Carpocyon
''Carpocyon'' is an extinct genus of the Borophaginae subfamily of canids native to North America. It lived from the Middle to the Late Miocene, 13.6 to 5.3 Ma Mya, existing for approximately . The four species in the genus varied in size, with ...
'', ''
Desmocyon
''Desmocyon'' is an extinct genus of the Borophaginae subfamily of canids native to North America. It lived from the Late Oligocene to the Early Miocene, 24.8—16.3 Annum, Mya, existing for approximately . It is a rarely found genus, with fossil ...
'', ''
Leptocyon
The genus ''Leptocyon'' (Greek: ''leptos'' slender + ''cyon'' dog) includes 11 species and was the first canine. They were small and weighed around . They first appeared in North America around 34 million years ago in the Oligocene at the same ...
Osbornodon
''Osbornodon'' (" Osborn's tooth") is an extinct genus of canid that were endemic to North America and which lived from the Oligocene to the Early Miocene, 33.9—15.97 Ma ( AEO), existing for approximately .
Otarocyon
''Otarocyon'' ("large eared dog") is an extinct genus of the Borophaginae subfamily of canids native to North America. It lived during the Oligocene epoch, about 34—30 Ma (million years ago). Fossils have been found only in Montana, Wyoming, ...
'', ''
Paracynarctus
''Paracynarctus'' is an extinct genus of the Borophaginae subfamily of canids native to North America. It lived from the Early Miocene to Middle Miocene 16.0—13.6 Annum, Ma, existing for approximately . It was likely an omnivore, and lacked th ...
'', ''
Paratomarctus
''Paratomarctus'' is an extinct monospecific genus of the Borophaginae subfamily of canids native to North America. It lived from the Middle to Late Miocene, 16.3—5.3 mya, existing for approximately . It was about the size of a coyote, and was ...
'', and ''
Phlaocyon
''Phlaocyon'' (from Greek ''phlao'', "eat greedily" and ''cyon'', "dog") is an extinct genus of the Borophaginae subfamily of canids native to North America. It lives from the Early Oligocene to the Early Miocene epoch 33.3–16.3 Annum, Mya, exi ...
'' (Wang, 1994; Wang et al., 1999). Of these, only ''Osbornodon'' belongs in the same
subfamily
In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...
as ''Cynodesmus'',
Hesperocyoninae
The extinct Hesperocyoninae are one of three subfamilies found within the canid family. The other two canid subfamilies are the extinct Borophaginae and extant Caninae.
Taxonomic history
Hesperocyoninae are basal canids that gave rise to th ...
. The remaining genera are placed in the subfamilies
Borophaginae
The extinct Borophaginae form one of three subfamilies found within the canid family. The other two canid subfamilies are the extinct Hesperocyoninae and extant Caninae. Borophaginae, called "bone-crushing dogs", were endemic to North America ...
and
Caninae
The Caninae, known as canines, are one of three subfamily, subfamilies found within the Canidae, canid family. The other two canid subfamilies are the extinct Borophaginae and Hesperocyoninae. The Caninae includes all living canids and their most ...
.
With unrelated species removed, ''Cynodesmus'' is currently restricted to the type species and the closely related ''C. martini'' (Wang, 1994).
Studies using the old conception of ''Cynodesmus'' considered it to be the ancestor of ''
Tomarctus
''Tomarctus'' is a canid genus of the extinct subfamily Borophaginae which inhabited most of North America during the late Early Miocene to the Early Barstovian age of the Middle Miocene (23—16 million years ago). ''Tomarctus'' existed for ...
'' (16-23 Ma) from which
wolves
The wolf (''Canis lupus''; plural, : wolves), also known as the gray wolf or grey wolf, is a large Canis, canine native to Eurasia and North America. More than thirty subspecies of Canis lupus, subspecies of ''Canis lupus'' have been reco ...
,
dog
The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...
s,
fox
Foxes are small to medium-sized, omnivorous mammals belonging to several genera of the family Canidae. They have a flattened skull, upright, triangular ears, a pointed, slightly upturned snout, and a long bushy tail (or ''brush'').
Twelve sp ...
es and fennecs developed. The ''Cynodesmus'' is a good example of
convergent evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...
because of other species such as the ''
Borophagus
''Borophagus'' ("gluttonous eater") is an extinct genus of the subfamily Borophaginae, a group of canids endemic to North America from the Middle Miocene epoch through the Early Pleistocene epoch 12—1.8 Mya.
Evolution
''Borophagus'', like o ...
'', the largest and most dominant canids of the
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58North American Coyote