Canidae () [2] is the biological family of carnivorous and omnivorous mammals that includes domestic dogs, wolves, foxes, jackals, coyotes, and many other lesser known extant and extinct dog-like mammals. A member of this family is called a canid
(/'ke?n?d/). The Canidae family is divided into two tribes: Canini (related to wolves) and Vulpini (related to foxes). The two species of the basal Caninae are more primitive and do not fit into either tribe.
The subdivision of Canidae into "foxes" and "true dogs" may not be in accordance with the actual relations; also the taxonomic classification of several canines is disputed. Recent DNA analysis shows that Canini (dogs) and Vulpini (foxes) are valid clades. (See phylogeny below). Molecular data implies a North American origin of living Canidae and an African origin of wolf-like canines (Canis, Cuon, and Lycaon).[3]
Currently, the domestic dog is listed as a subspecies of Canis lupus, C. l. familiaris, and the dingo (also considered a domestic dog) as C. l. dingo, provisionally a separate subspecies from C. l. familiaris; the red wolf, eastern Canadian wolf, and Indian wolf are recognized as subspecies.[1] Many sources list the domestic dog as Canis familiaris, but others, including the Smithsonian Institution and the American Society of Mammalogists, more precisely list it as a subspecies of C. l. familiaris; the red wolf, eastern Canadian wolf, and Indian wolf may or may not be separate species; the dingo has been in the past variously classified as Canis dingo, Canis familiaris dingo and Canis lupus familiaris dingo.
An approximate timescale of key events in canid evolution. For precise dates, see text. Axis scale: millions of years ago.
Pre?
?
O
S
D
C
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K
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Eocene epoch
Carnivorans evolved from miacoids about 55 million years ago
during the late Paleocene.[4] Then, about 50 million years ago, the carnivorans split into two main divisions: caniforms (dog-like) and feliforms (cat-like). By 40 million years ago the first clearly identifiable member of the dog family Canidae had arisen. It was called Prohesperocyon wilsoni and was found in what is now southwestern Texas. This fossil species bears a combination of features that definitively mark it as a canid: teeth that include the loss of the upper third molar (a general trend toward a more shearing bite), and the characteristically enlarged bony bulla (the rounded covering over the middle ear). Based on what we know about its descendants, Prohesperocyon likely had slightly more elongated limbs than its predecessors, along with toes that were parallel and closely touching, rather than splayed, as in bears.[5]
The Canidae family soon subdivided into three subfamilies, each of which diverged during the Eocene: Hesperocyoninae (~39.74-15 Mya), Borophaginae (~34-2 Mya), and the Caninae (~34-0 Mya) lineage that led to present-day canids (wolves, foxes, coyotes, jackals, and domestic dogs). Each of these groups showed an increase in body mass with time, and sometimes exhibited a specialised hypercarnivorous diet that made them prone to extinction.[6]:Fig. 1 Only the Caninae lineage, commonly referred to as "canines", survived to the present day.
Oligocene epoch
By the Oligocene, all three subfamilies of canids (Hesperocyoninae, Borophaginae, and Caninae) had appeared in the fossil records of North America. The earliest and most primitive branch of the Canidae was the Hesperocyoninae lineage, which
included the coyote-sized Mesocyon of the Oligocene (38-24 Mya). These early canids probably evolved for fast pursuit of prey in a grassland habitat, and resembled modern civets in appearance. Hesperocyonines eventually became extinct in the middle Miocene. One of the early member of the Hesperocyonines, the genus Hesperocyon, gave rise to Archaeocyon and Leptocyon. These branches led to the borophagine and canine radiations.[7]
Miocene epoch
Around 9-10 Mya during the Late Miocene, Canis, Urocyon, and Vulpes genera expanded from southwestern North America. This was the point where the canine radiation began. The success of these canines was related to the development of lower carnassials that were capable of both mastication and shearing. Around 8 Mya, Beringia offered the canines a way to enter Eurasia.
Pliocene epoch
During the
Pliocene around (4-5 Mya) Canis lepophagus appeared in North America. This was small and sometimes coyote-like. Others were wolf-like in characteristics. It is theorized that Canis latrans (the coyote) descended from Canis lepophagus.[8]
The formation of the Isthmus of Panama about 3 Mya joined South America to North America, allowing canids to invade the former, where they diversified.
Pleistocene epoch
Around 1.5 to 1.8 Mya, a variety of wolves were present in Europe. Also, the North American wolf line appeared with Canis edwardii, clearly identifiable as a wolf. Canis rufus appeared, possibly a direct descendent of Canis edwardii. Around 0.8 Mya, Canis ambrusteri emerged in North America. A large wolf, it was found all over the continent. It is thought that this species migrated to South America where it became the ancestor of Canis
dirus, the dire wolf.
At 0.3 Mya Canis lupus (the gray wolf) was fully developed and had spread throughout Europe and northern Asia. Beringia offered a way to North America.[9] At around 100,000 years ago, the dire wolf, one of the largest members of the dog family, had spread from South America to southern Canada and from coast to coast. The dire wolf shared its habitat with the gray wolf. Around 8,000 years ago the dire wolf became extinct.
Wild canids are found on every continent except Antarctica, and inhabit a wide range of different habitats, including deserts, mountains, forests, and grassland. They vary in size from the fennec fox at 24 cm (9.4 in) long, to the gray wolf, which may be up to 2 m (6.6 ft) long, and can weigh up to 80 kg (180 lb).
With the exceptions of the bush dog, rac
coon dog and some domestic breeds, canids
have relatively long legs and lithe bodies, adapted for chasing prey. All canids are digitigrade, meaning that they walk on their toes. They possess bushy tails, non-retractile claws, and, excepting the African wild dog (Lycaon pictus), a dewclaw on the front feet. They possess a baculum, which together with a cavernous body helps to create a copulatory tie during mating, locking the animals together for up to an hour. Young canids are born blind, with their eyes opening a few weeks after birth.[10] All living canids (Caninae) have a ligament analogous to the nuchal ligament of ungulates used to maintain the posture of the head and neck with little active muscle exertion; this ligament allows them to conserve energy while running long distances following scent trails with their nose to the ground.[11] However, at least some Borophaginae (such as Aelurodon) are believed to lack this ligament based upon skeletal details of the neck.[11]
Gray wolf pack hunting an American bison in Yellowstone National Park.
Only a few species are arboreal - the North American gray fox, the closely related Channel Island fox,[12] and the raccoon dog habitually climb trees.[13][14][15]
Social behavior
Almost all canids are social animals and live together in groups. In most foxes and in many of the true dogs, a male and female pair work together to hunt and to raise their young. Gray wolves and some of the other larger canids live in larger groups called packs. African wild dogs have the largest packs, which can number as many as 90 animals. Some species form packs or live in small family groups depending on the circumstances, including the type of available food. In most species, there are also some individuals who live on their own. Within a canid pack, there is a system of dominance so that the strongest, most experienced animals lead the pack. In most cases, the dominant male and female are the only pack members to breed.
Canids communicate with each
other by scent signals, by visual clues and gestures, and by vocalizations such as growls, barks, and howls. In most cases, groups have a home territory from which they drive out others. The territory is marked by leaving urine scent marks, which warn trespassing individuals.[16]
Most canids bear young once a year, from 1 to 16 or more (in the case of the African wild dog) at a time. The young are born small and helpless and require a long period of care. They are kept in a den, most often dug into the ground, for warmth and protection. When they begin eating solid food, both parents, and often other pack members, bring food back for them from the hunt. This is most often vomited up from the adult's
stomach. Young canids may take a year to mature and learn the skills they need to survive.[17]
Dentition
Italian wolf skull
Most canids have 42 teeth, with a dental formula of: . As in other members of Carnivora, the upper fourth premolar and lower first molar are adapted as carnassial teeth for slicing flesh. The molar teeth are strong in most species, allowing the animals to crack open bone to reach the marrow. The deciduous or baby teeth formula in canids is 3 1 3; molars are
completely absent.
Classification of Hesperocyoninae from Wang (1994)[18] and Borophaginae from Wang, Tedford, Taylor (1999),[19] and Caninae from Tedford, Wang, Taylor (2009)[20] except where noted.
One canid, the domestic dog, a subspecies of the gray wolf, long ago entered into a partnership with humans and today remains one of the most widely kept domestic animals in the world and serves humanity in a great many important ways.
Among canids, only the gray wolf has been known to prey on humans.[24] There are at least two records of coyotes killing humans,[25] and two of golden jackals killing children.[26] Some canid species have also been trapped and hunted for their fur and, especially the gray wolf and the red fox, for sport. Some canids are now endangered in the wild due to hunting, habitat loss, and the
introduction of diseases from domestic dogs.[27]
An approximate timescale of key events in canid evolution. For precise dates, see text. Axis scale: millions of years ago.
Pre?
?
O
S
D
C
P
T
J
K
Pg
N
?
Eocene epoch
Carnivorans evolved from miacoids about 55 million years ago during the late Paleocene.[4] Then, about 50 million years ago, the carnivorans split into two main divisions: caniforms (dog-like) and feliforms (cat-like). By 40 million years ago the first clearly identifiable member of the dog family Canidae had arisen. It was called Prohesperocyon wilsoni and was found in what is now southwestern Texas. This fossil species bears a combination of features that definitively mark it as a canid: teeth that include the loss of the upper third molar (a general trend toward a more shearing bite), and the characteristically enlarged bony bulla (the rounded covering over the middle ear). Based on what we know about its descendants, Prohesperocyon likely had slightly more elongated limbs than its predecessors, along with toes that were parallel and closely touching, rather than splayed, as in bears.[5]
The Canidae family soon subdivided
into three subfamilies, each of which diverged during the Eocene: Hesperocyoninae (~39.74-15 Mya), Borophaginae (~34-2 Mya), and the Caninae (~34-0 Mya) lineage that led to present-day canids (wolves, foxes, coyotes, jackals, and domestic dogs). Each of these groups showed an increase in body mass with time, and sometimes exhibited a specialised hypercarnivorous diet that made them prone to extinction.[6]:Fig. 1 Only the Caninae lineage, commonly referred to as "canines", survived to the present day.
Oligocene epoch
By the Oligocene, all three subfamilies of canids (Hesperocyoninae, Borophaginae, and Caninae) had appeared in the fossil records of North America. The earliest and most primitive branch of the Canidae was the Hesperocyoninae lineage, which included the coyote-sized Mesocyon of the Oligocene (38-24 Mya). These early canids
probably evolved for fast pursuit of prey in a grassland habitat, and resembled modern civets in appearance. Hesperocyonines eventually became extinct in the middle Miocene. One of the early member of the Hesperocyonines, the genus Hesperocyon, gave rise to Archaeocyon and Leptocyon. These branches led to the borophagine and canine radiations.[7]
Miocene epoch
Around 9-10 Mya during the Late Miocene, Canis, Urocyon, and Vulpes genera expanded from southwestern North America. This was the point where the canine radiation began. The success of these canines was related to the development of lower carnassials that were capable of both mastication and shearing. Around 8 Mya, Beringia offered the canines a way to enter Eurasia.
Pliocene epoch
During the Pliocene around (4-5 Mya) Canis lepophagus appeared in North America. This was small and
sometimes coyote-like. Others were wolf-like in characteristics. It is theorized that Canis latrans (the coyote) descended from Canis lepophagus.[8]
The formation of the Isthmus of Panama about 3 Mya joined South America to North America, allowing canids to invade the former, where they diversified.
Pleistocene epoch
Around 1.5 to 1.8 Mya, a variety of wolves were present in Europe. Also, the North American wolf line appeared with Canis edwardii, clearly identifiable as a wolf. Canis rufus appeared, possibly a direct descendent of Canis edwardii. Around 0.8 Mya, Canis ambrusteri emerged in North America. A large wolf, it was found all over the continent. It is thought that this species migrated to South America where it became the ancestor of Canis dirus, the dire wolf.
At 0.3 Mya Canis lupus (the gray wolf) was fully developed and
had spread throughout Europe and northern Asia. Beringia offered a way to North America.[9] At around 100,000 years ago, the dire wolf, one of the largest members of the dog family, had spread from South America to southern Canada and from coast to coast. The dire wolf shared its habitat with the gray wolf. Around 8,000 years ago the dire wolf became extinct.
Wild canids are found on every continent except Antarctica, and inhabit a wide range of different habitats, including deserts, mountains, forests, and grassland. They vary in size from the fennec fox at 24 cm (9.4 in) long, to the gray wolf, which may be up to 2 m (6.6 ft) long, and can weigh up to 80 kg (180 lb).
With the exceptions of the bush dog, raccoon dog and some domestic breeds, canids have relatively long legs and lithe bodies, adapted for chas
ing prey. All canids are digitigrade,
meaning that they walk on their toes. They possess bushy tails, non-retractile claws, and, excepting the African wild dog (Lycaon pictus), a dewclaw on the front feet. They possess a baculum, which together with a cavernous body helps to create a copulatory tie during mating, locking the animals together for up to an hour. Young canids are born blind, with their eyes opening a few weeks after birth.[10] All living canids (Caninae) have a ligament analogous to the nuchal ligament of ungulates used to maintain the posture of the head and neck with little active muscle exertion; this ligament allows them to conserve energy while running long distances following scent trails with their nose to the ground.[11] However, at least some Borophaginae (such as Aelurodon) are believed to lack this ligament
based upon skeletal details of the neck.[11]
Gray wolf pack hunting an American bison in Yellowstone National Park.
Only a few species are arboreal - the North American gray fox, the closely related Channel Island fox,[12] and the raccoon dog habitually climb trees.[13][14][15]
Social behavior
Almost all canids are social animals and live together in groups. In most foxes and in many of the true dogs, a male and female pair work together to hunt and to raise their young. Gray wolves and some of the other larger canids live in larger groups called packs. African wild dogs have the largest packs, which can number as many as 90 animals. Some species form packs or live in small family groups depending on the circumstances, including the type of available food. In most species, there are also some individuals who live on their own. Within a canid pack, there is a system of dominance so that the strongest, most experienced animals lead the pack. In most cases, the dominant male and female are the only pack members to breed.
Canids communicate with each other by scent signals, by visual clues and gestures, and by vocalizations such as growls, barks, and howls. In most cases, groups have a home territory from which
they drive out others. The territory is marked by leaving urine scent marks, which warn trespassing individuals.[16]
Most canids bear young once a year, from 1 to 16 or more (in the case of the African wild dog) at a time. The young are born small and helpless and require a long period of care. They are kept in a den, most often dug into the ground, for warmth and protection. When they begin eating solid food, both parents, and often other pack members, bring food back for them from the hunt. This is most often vomited up from the adult's
stomach. Young canids may take a year to mature and learn the skills they need to survive.[17]
Dentition
Italian wolf skull
Most canids have 42 teeth, with a dental formula of: . As in other members of Carnivora, the upper fourth premolar and lower first molar are adapted as carnassial teeth for slicing flesh. The molar teeth are strong in most species, allowing the animals to crack open bone to reach the marrow. The deciduous or baby teeth formula in canids is 3 1 3; molars are
completely absent.
Classification of Hesperocyoninae from Wang (1994)[18] and Borophaginae from Wang, Tedford, Taylor (1999),[19] and Caninae from Tedford, Wang, Taylor (2009)[20] except where noted.
One canid, the domestic dog, a subspecies of the gray wolf, long ago entered into a partnership with humans and today remains one of the most widely kept domestic animals in the world and serves humanity in a great many important ways.
Among canids, only the gray wolf has been known to prey on humans.[24] There are at least two records of coyotes killing humans,[25] and two of golden jackals killing children.[26] Some canid species have also been trapped and hunted for their fur and, especially the gray wolf and the red fox, for sport. Some canids are now endangered in the wild due to hunting, habitat loss, and the
introduction of diseases from domestic dogs.[27]
^ Kauhala K. & Saeki M. (2004). ?Raccoon Dog?. Canid Species Accounts. IUCN/SSC Canid Specialist Group. Pridobljeno 15.4.2009.
^ Ikeda, Hiroshi (August 1986). "Old dogs, new tricks: Asia's raccoon dog, a venerable member of the canid family is pushing into new frontiers". Natural History95 (8): p40,44.
^ Nowak, R. M., and J. L. Paradiso. 1983. Walker's Mammals of the World. Baltimore, Maryland: The Johns Hopkins University Press. ISBN 0801825253.
^ Voelker, W. 1986. The Natural History of Living Mammals. Medford, New Jersey: Plexus Publishing. ISBN 0937548081
^ Wang, Xiaoming (1994). "Phylogenetic systematics of the Hesperocyoninae". Bulletin of the American Museum of Natural History221: 1?207. hdl:2246/829.
^ Wang, Xiaoming (1999). "Phylogenetic systematics of the Borophaginae". Bulletin of the American Museum of Natural History243: 1?391. hdl:2246/1588.
^ ab Tedford, Richard; Xiaoming Wang, Beryl E. Taylor (2009). "Phylogenetic systematics of the North American fossil Caninae (Carnivora: Canidae)". Bulletin of the American Museum of Natural History325: 1?218. doi:10.1206/574.1.
^ ab Hayes, F.G. (2000). "The Brooksville 2 local fauna (Arikareean, latest Oligocene) Hernando County, Florida". Bulletin of the Florida Museum of Natural History43 (1): 1?47.
Xiaoming Wang, Richard H. Tedford, Mauricio Ant?n, Dogs: Their Fossil Relatives and Evolutionary History, New York : Columbia University Press, 2008; ISBN 978-0-231-13528-3
Aelurodon is an extinct canine genus of the subfamily Borophaginae which lived from the Barstovian land mammal age (16 Mya) of the middle Miocene to the Clarendonian age of the late Miocene (9 Mya). Aelurodon existed for approximately 7 million years. [more]
The short-eared dog (Atelocynus microtis), also known as the short-eared fox or the short-eared zorro, is a unique and elusive canid species endemic to the Amazonian basin. This is the only species assigned to the genus Atelocynus. [more]
Borophagus
Borophagus ("devouring glutton") is an extinct of the subfamily Borophaginae, a group of canids endemic to North America from the early Miocene epoch (23.3 Mya) through the Zanclean stage of the Pliocene epoch (3.6 Mya). Borophagus existed for approximately . [more]
The crab-eating fox (Cerdocyon thous), also known as the forest fox, wood fox, and the common fox, is an extant species of medium-sized canid endemic to the central part of South America and which appeared during the Pliocene epoch. Cerdocyon comes from the Greek words kerdo (meaning fox) and cyon (dog) referring to the dog and fox- like characters of this animal. [more]
Chrysocyon
The maned wolf (Chrysocyon brachyurus) is the largest canid of South America, resembling a large fox with reddish fur. [more]
Cormocyon
Cuon
The Dhole (Cuon alpinus), also known as the Asiatic Wild Dog, Indian Wild Dog, or Red Dog, is a of Asian canid, and the only member of the genus Cuon. [more]
Dusicyon is a genus of extinct South American canids. The type species is Dusicyon australis, the extinct Falkland Islands Wolf. In 1914, Oldfield Thomas established the genus Dusicyon, in which he included the Culpeo and other South American foxes. These other canids were removed to Lycalopex by Langguth in 1975. , widely distributed in the late Pleistocene from Uruguay through Buenos Aires Province to southernmost Chile, may be a close relative of the Falkland Islands Wolf. It disappeared in the late Holocene at least 3000 years BP in the island of Tierra del Fuego and about 1600 years BP in the continent. [more]
Epicyon ("near dog") is a large extinct genus of the subfamily Borophaginae ("bone-crushing dogs"), native to North America. It lived from the Hemingfordian of the Early Miocene (20.6 Mya) to the Hemphillian age of the Late Miocene (5.330 Mya). Epicyon existed for about 15.5 million years. [more]
Leptocyon is an extinct ancient ancestor of today's foxes and dogs, that lived during the Early Miocene 23 Mya with Nothocyon leading to the Borophaginae and 2nd and 3rd canine radiations. Species: L. gregorii,L. vafer,L. vulpinus.[more]
Lupus
Lycalopex
Lycalopex is the name for some South American members of the Canidae family. The common name for the genus is zorro, from Spanish, and raposa, from Portuguese, both words standing for fox. The most numerous species of this genus is probably Lycalopex griseus, the South American Gray Fox, with large ears and a highly marketable, russet-fringed pelt. This genus is more closely related to the dog-like canids than to the true foxes. The zorros are hunted in Argentina for their durable, soft pelt. In Argentina they have the name of 'lamb-killer'. In reality, zorros rarely kill lambs, although, if hunger strikes, they will prey on weak or sick infants. [more]
Nyctereutes is an east Asian genus of the family Canidae, consisting of just one living species, the Raccoon Dog. Nyctereutes appeared about 9.0 Ma, with all but one species becoming extinct before the Pleistocene. [more]
Osbornodon
Osteoborus
Borophagus ("devouring glutton") is an extinct of the subfamily Borophaginae, a group of canids endemic to North America from the early Miocene epoch (23.3 Mya) through the Zanclean stage of the Pliocene epoch (3.6 Mya). Borophagus existed for approximately . [more]
Otarocyon
Otocyon
The bat-eared fox (Otocyon megalotis) is a canid of the African savanna, named for its large ears. Fossil records show this canid to first appear during the middle Pleistocene, about 800,000 years ago. [more]
Prototcyon is an extinct genus of small omnivorous canid endemic to South America during the middle to Late Pleistocene living from 1.2 Ma to 11,000 years ago and existed for approximately 1.189 million years. [more]
Protomarctus
Psalidocyon
Pseudalopex
Lycalopex is the name for some South American members of the Canidae family. The common name for the genus is zorro, from Spanish, and raposa, from Portuguese, both words standing for fox. The most numerous species of this genus is probably Lycalopex griseus, the South American Gray Fox, with large ears and a highly marketable, russet-fringed pelt. This genus is more closely related to the dog-like canids than to the true foxes. The zorros are hunted in Argentina for their durable, soft pelt. In Argentina they have the name of 'lamb-killer'. In reality, zorros rarely kill lambs, although, if hunger strikes, they will prey on weak or sick infants. [more]
Pseudocynodictis
Rhizocyon
Speothos
Speothos is a genus of canid found in Central and South America. The genus includes the living Bush Dog, Speothos venaticus, as well as an extinct Pleistocene species, Speothos pacivorus. Surprisingly, the fossil species was identified and named prior to the discovery of the extant species, with the result that the type species of Speothos is S. pacivorus. [more]
The genus Urocyon (from the Greek word for 'tailed dog') is a genus that contains two (or possibly three) living Western Hemisphere foxes in the family Canidae, the Gray Fox (Urocyon cinereoargenteus) and the closely related Island Fox (Urocyon littoralis) which is a dwarf cousin of the Gray Fox; as well as one fossil species, Urocyon progressus. [more]
Vulpes
Vulpes is a genus of the Canidae family. Its members are referred to as 'true foxes', although there are species in other genera whose common names include the word 'fox'. True foxes are distinguished from members of the genus Canis, such as wolves, coyotes, and jackals, by their smaller size and flatter skulls. They have black triangular markings between the eyes and nose, and the tip of the tail is often a different color from the rest of the pelt. [more]
At least 112 species and subspecies belong to the Genus Vulpes.
More info about the Genus Vulpes may be found here.
^ Kauhala K. & Saeki M. (2004). ?Raccoon Dog?. Canid Species Accounts. IUCN/SSC Canid Specialist Group. Pridobljeno 15.4.2009.
^ Ikeda, Hiroshi (August 1986). "Old dogs, new tricks: Asia's raccoon dog, a venerable member of the canid family is pushing into new frontiers". Natural History95 (8): p40,44.
^ Nowak, R. M., and J. L. Paradiso. 1983. Walker's Mammals of the World. Baltimore, Maryland: The Johns Hopkins University Press. ISBN 0801825253.
^ Voelker, W. 1986. The Natural History
of Living Mammals. Medford, New Jersey: Plexus Publishing. ISBN 0937548081
^ Wang, Xiaoming (1994). "Phylogenetic systematics of the Hesperocyoninae". Bulletin of the American Museum of Natural History221: 1?207. hdl:2246/829.
^ Wang, Xiaoming (1999). "Phylogenetic systematics of the Borophaginae". Bulletin of the American Museum of Natural History243: 1?391. hdl:2246/1588.
^ ab Tedford, Richard; Xiaoming Wang, Beryl E. Taylor (2009). "Phylogenetic systematics of the North Amer
ican fossil Caninae (Carnivora: Canidae)". Bulletin of the American Museum of Natural History325: 1?218. doi:10.1206/574.1.
^ ab Hayes, F.G. (2000). "The Brooksville 2 local fauna (Arikareean, latest Oligocene) Hernando County, Florida". Bulletin of the Florida Museum of Natural History43 (1): 1?47.
. As in other members of Carnivora, the upper fourth premolar and lower first molar are adapted as carnassial teeth for slicing flesh. The molar teeth are strong in most species, allowing the animals to crack open bone to reach the marrow. The deciduous or baby teeth formula in canids is 3 1 3; molars are
completely absent.
