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Carnivora

Carnivora

Temporal range: 42 –0Ma

Middle Eocene to Recent

Various carnivorans, with feliforms (tiger, spotted hyena and African civet) to the left, and caniforms (brown bear, grey wolf and

wolverine) to the right.

Scientific classification

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Infraclass: Eutheria

Superorder: LaurasiatheriaOrder: Carnivora

Bowdich, 1821

Families

• 17, See classification

The diverse order Carnivora (/kɑrˈnɪvərə / or / ̩kɑrnɪˈvɔərə /; from Latin carō (stem carn-) "flesh", + vorāre  "to

devour") includes over 280 species of placental mammals. Its members are formally referred to as carnivorans,

whereas the word "carnivore" (often popularly applied to members of this group) can refer to any meat-eating

organism. Carnivorans are the most diverse in size of any mammalian order, ranging from the least weasel ( Mustela

nivalis), at as little as 25 g (0.88 oz) and 11 cm (4.3 in), to the polar bear ( Ursus maritimus), which can weigh up to1,000 kg (2,200 lb), to the southern elephant seal ( Mirounga leonina), whose adult males weigh up to 5,000 kg

(11,000 lb) and measure up to 6.9 m (23 ft) in length.

The first carnivoran was a carnivore, and nearly all carnivorans today primarily eat meat. Some, such as cats and

pinnipeds, depend entirely on meat for their nutrition. Others, such as raccoons and bears, depending on the local

habitat, are more omnivorous; the giant panda is almost exclusively a herbivore, but will take fish, eggs and insects,

while the polar bear's harsh habitat forces it to subsist mainly on prey. Carnivorans have teeth, claws, and binocular

vision adapted for catching and eating other animals. Many hunt in packs and are social animals, giving them an

advantage over larger prey.

Carnivorans apparently evolved in North America out of members of the family Miacidae (miacids) about 42 million

years ago. They soon split into cat-like and dog-like forms (Feliformia and Caniformia). Their molecular

phylogeny[1] shows the extant Carnivora are a monophyletic group, the crown-group of the Carnivoramorpha.

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Distinguishing features

A brown bear, showing the sharp teeth and claws

characteristic of carnivorans

Most carnivorans are terrestrial; they usually have strong, sharp claws,

with never fewer than four toes on each foot, and well-developed,

prominent canine teeth, cheek teeth (premolars, and molars) that

generally have cutting edges. The last premolar of the upper jaw and

first molar of the lower are termed the carnassials or sectorial teeth.

These blade-like teeth occlude (close) with a scissor-like action for

shearing and shredding meat. Carnassials are most highly developed in

the Felidae and the least developed in the Ursidae. Carnivorans have

six incisors and two conical canines in each jaw. The only two

exceptions to this are the sea otter ( Enhydra lutris), which has four

incisors in the lower jaw, and the sloth bear ( Melursus ursinus), which

has four incisors in the upper jaw. The number of molars and

premolars is variable between carnivoran species, but all teeth are

deeply rooted and are diphyodont. Incisors are retained by carnivorans

and the third incisor is commonly large and sharp (canine-like).

Carnivorans have either four or five digits on each foot, with the first

digit on the forepaws, also known as the dew claw, being vestigial in

most species and absent in some.

The Canoidea superfamily (or Caniformia suborder)  – Canidae (wolves, dogs and foxes), Mephitidae (skunks and

stink badgers), Mustelidae (weasels, badgers, and otters), Procyonidae (raccoons), Ursidae (bears), Otariidae (eared

seals), Odobenidae (walrus), and Phocidae (earless seals) (the last three families formerly classified in the suborder

Pinnipedia) and the extinct family Amphicyonidae (bear-dogs)  – are characterized by having nonchambered or

partially chambered auditory bullae, nonretractable claws, and a well-developed baculum. Most species are rather

simply colored, lacking the flashy spotted or rosetted coats like many species of felids and viverrids have. This isbecause Canoidea tend to range in the temperate and subarctic biomes, although Mustelidae and Procyonidae have a

few tropical species. Most are terrestrial, although a few species, like procyonids, are arboreal. All families except

the Canidae and a few species of Mustelidae are plantigrade. Diet is varied and most tend to be omnivorous to some

degree, and thus the carnassial teeth are less specialized. Canoidea have more premolars and molars in an elongated

skull.

The Feloidea superfamily (or Feliformia suborder) – Felidae (cats), Prionodontidae (Asiatic linsangs), Herpestidae

(mongooses), Hyaenidae (hyenas), Viverridae (civets), and Eupleridae (Malagasy carnivorans), as well as the extinct

family Nimravidae (paleofelids)  – often have spotted, rosetted or striped coats, and tend to be more brilliantly

colored than their Canoidean counterparts. This is because these species tend to range in tropical habitats, although afew species do inhabit temperate and subarctic habitats. Many are arboreal or semiarboreal, and the majority are

digitigrade. Diet tends to be more strictly carnivorous, especially in the Felidae family. They have fewer teeth and

shorter skulls, with much more specialized carnassials meant for shearing meat. Felidae claws are retractile, or

rarely, semiretractile. The terminal phalanx, with the claw attached, folds back in the forefoot into a sheath by the

outer side of the middle phalanx of the digit, and is retained in this position when at rest by a strong elastic ligament.

In the hindfoot, the terminal joint or phalanx is retracted on to the top, and not the side of the middle phalanx. Deep

flexor muscles straighten the terminal phalanges, so the claws protrude from their sheaths, and the soft "velvety" paw

becomes suddenly converted into a formidable weapon. The habitual retraction of the claws preserves their points

from wear.

The Pinnipedia superfamily (walruses, seals, and sea lions), now considered to be part of Caniformia, are medium tolarge (to 6.5 m) aquatic mammals. Being homeothermic (warm-blooded) marine mammals, pinnipeds need a low

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surface area to body mass ratio. Otherwise, they would suffer from excessive heat loss due to water's high capacity

for heat conduction. The body is usually insulated with a thick layer of fat called blubber and typically covered with

hair. The digits are not separate, but connected by a thick web that forms flippers for swimming; thus, the forelimbs

and hindlimbs are transformed into paddles. This enables them to dive at extreme depths (600 m for the Weddell

seal). They can remain underwater for long periods of time, sometimes an hour or more, but most dives are usually

short. The facial region of skull is relatively small, with pinnae very small or lacking, and the vibrissae are well

developed. The molariform teeth are mostly homodont and the canines are well developed. The tail is very short or

absent, the ears are small or absent as well, and the external genitalia are hidden in slits or depressions in the body.

Skull structure

Skull of  Hyaena eximia

Carnassials of an Eurasian wolf 

Members of Carnivora have a characteristic skull shape with relatively

large brains encased in a heavy skull. The skull has a highly developed

zygomatic arch just behind the maxilla (common to all mammals and

their cynodont forebears), and they have ossified external auditory

bullae. Feloidea have a two-chambered auditory bullae. In addition to

allowing extra room for the passage of muscles to work the lower jaw,the zygomatic arch also allows for differentiation of separate muscle

groups to be involved in biting and chewing. Masseters attach from the

dentary (specifically, the masseteric fossa) to the zygomatic arch and

onto the maxilla in front of the arch, providing crushing force. The

temporalis attaches from the dentary (specifically, the coronoid

process) to the side of the braincase, providing torque about the axis of 

 jaw articulation. In comparing the skulls of carnivores and herbivores,

it can be seen that the shearing force of the temporalis is somewhat

more important to carnivores, which have more room on the braincase

(this is not unrelated to carnivoran intelligence) and commonly develop

a sagittal crest (running from posterior to anterior on the skull),

providing yet additional room for temporalis attachment. Carnivoran

 jaws can only move on a vertical axis, in an up-and-down motion, and

cannot move from side-to-side. The jaw joint in carnivores tends to lie

within the plane of tooth occlusion, an arrangement that further

emphasizes shearing (as in a pair of scissors). In herbivores, the

crushing force of the masseters is relatively more important than is shearing. The jaw joint is generally well above

the plane of tooth occlusion, allowing extra room for masseteric attachment on the dentary and causing the rotation

of the lower jaw to be translated into straight-ahead crushing force between the teeth of the upper and lower jaws.

Physiology

Carnivora have a simple stomach designed to digest primarily meat, as compared to the elaborate digestive systems

of herbivorous animals, which are necessary to break down tough, complex plant fibers. The caecum is either absent

or short and simple, and the colon is not sacculated or much wider than the small intestine. Most species of 

Carnivora are, to some degree, omnivorous, except the Felidae and Pinnipedia, which are obligate carnivores. Most

have highly developed senses, especially vision and hearing, and often a highly acute sense of smell in many species,

such as in the Canoidea. They are excellent runners: some are long-distance runners, but more commonly are

sprinters. Even bears and raccoons, although seemingly slow and clumsy, are capable of remarkable bursts of speed.

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Diet specializations

Carnivorans include carnivores, omnivores, and even a few primarily herbivorous species, such as the giant panda

and the binturong. Important teeth for carnivorans are the large, slightly recurved canines, used to dispatch prey, and

the carnassial complex, used to rend meat from bone and slice it into digestible pieces. Dogs have molar teeth behind

the carnassials for crushing bones, but cats have only a greatly reduced, functionless molar behind the carnassial in

the upper jaw. Cats will strip bones clean but will not crush them to get the marrow inside. Omnivores, such as bearsand raccoons, have developed blunt, molar-like carnassials. Carnassials are a key adaptation for terrestrial vertebrate

predation; all other placental orders are primarily herbivores, insectivores, or aquatic.

Reproductive system

A cat with a litter of four kittens

Carnivorans tend to produce a single litter annually, but some produce

multiple litters a year, and larger carnivorans, like bears, have gaps of 

2 –3 yr between litters. The average gestation period lies between 50

and 115 days, although the ursids and mustelids have delayed

implantation, thus extending the gestation period six to 9 months

beyond the normal period. Litter sizes are usually small, ranging from

one to 13 young, which are born with underdeveloped eyes and ears. In

most species, the mother has exclusive or at least primary care of the

offspring. Many species of carnivorans are solitary, but a few are

gregarious.

Phylogeny

Artist's impression of one of the first carnivorans,

a miacid

Carnivorans evolved from members of the paraphyletic family

Miacidae (miacids). The transition from Miacidae to Carnivora was ageneral trend in the middle and late Eocene, with taxa from both North

America and Eurasia involved. The divergence of carnivorans from

other miacids, as well as the divergence of the two clades within

Carnivora, Caniformia and Feliformia, is now inferred to have

happened in the middle Eocene, about 42 million years ago (mya).

Traditionally, the extinct family Viverravidae (viverravids) had been

thought to be the earliest carnivorans, with fossil records first

appearing in the Paleocene of North America about 60 mya, but

recently described evidence from cranial morphology now places them

outside the order Carnivora.[]

The Miacidae are not a monophyletic group, but a paraphyletic array of stem taxa. Today, Carnivora is restricted to

the crown group, Carnivora and miacoids are grouped in the clade Carnivoramorpha, and the miacoids are regarded

as basal carnivoramorphs. Based on dental features and braincase sizes, it is now known that Carnivora must have

evolved from a form even more primitive than Creodonta, and thus these two orders may not even be sister groups.[]

The Carnivora, Creodonta, Pholidota, and a few other extinct orders are informally grouped together in the clade

Ferae. Older classification schemes divided the order into two suborders: Fissipedia (which included the families of 

primarily land Carnivora) and Pinnipedia (which included the true seals, eared seals, and walrus). However, it is now

recognized that the Fissipedia is a paraphyletic group and that the pinnipeds were not the sister group to the fissipeds

but rather had arisen from among them.

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a period spanning the Eocene/Oligocene boundary, a dramatic climatic cooling event occurred.[]

A recent study has finally resolved the exact position of  Ailurus: the red panda is neither a procyonid nor an ursid,

but forms a monotypic family, with the other musteloids as its closest living relatives. The same study also showed

that the mustelids are not a primitive family, as was once thought. Their small body size is a secondary trait —the

primitive body form of the arctoids was large, not small. [] Recent molecular studies also suggest that the endemic

Carnivora of Madagascar, including three genera usually classed with the civets and four genera of mongoosesclassed with the Herpestidae, are all descended from a single ancestor. They form a single sister taxon to the

Herpestidae. The hyenas are also closely related to this clade.

Classification

Least weasel, the smallest carnivoran

Southern elephant seal, the largest carnivoran

The most common modern classification scheme divides the Carnivora

into fifteen living, and a number of extinct, families, as follows:[]

•• ORDER CARNIVORA

• Suborder Feliformia ("cat-like")

• Family †Stenoplesictidae

• Family †Percrocutidae

• Family †Nimravidae: false sabre-tooth cats (5 –36 mya)

• Family Nandiniidae: African palm civet; one species

• Superfamily Feloidea

• Family Prionodontidae: Asiatic linsangs; two species in

one genus

• Family †Barbourofelidae (6 –18 mya)

• Family Felidae: cats; 40 species in 15 genera

• Infraorder Viverroidea• Family Viverridae: civets and allies; 36 species in 14

genera

• Superfamily Herpestoidea

• Family Hyaenidae: hyenas and aardwolf; four species in

three genera

• Family Eupleridae: Malagasy carnivorans; 10 species in seven genera

• Family Herpestidae: mongooses and allies; 33 species in 14 genera

• Suborder Caniformia ("dog-like")

• Family †Amphicyonidae: bear-dogs (9 –37 mya)• Family Canidae: dogs and allies; 35 species in 12 genera

• Infraorder Arctoidea

• Superfamily Ursoidea

• Family †Hemicyonidae: (2 –22 mya)

• Family Ursidae: bears; eight species in five genera

• Superfamily Musteloidea

• Family Ailuridae: red panda; one species

• Family Mephitidae: skunks and stink badgers; 12 species in four genera

• Family Mustelidae: weasels and allies; 57 species in 22 genera

• Family Procyonidae: raccoons and allies; 15 species in six genera

• Superfamily Pinnipedia

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• Family †Enaliarctidae: (23 –20 mya?)

• Family Odobenidae: walrus; one species

• Family Otariidae: eared seals; 15 species in seven genera

• Family Phocidae: true seals; 18 species in 13 genera

Phylogenetic tree

Brown bear, the largest land carnivoran next to

the polar bear

Cat and dog, domesticated carnivorans

Carnivora

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Feliformia

Nimravidae† 

Stenoplesictidae†

Percrocutidae†

Nandiniidae

Prionodontidae

Barbourofelidae†

Felidae

Viverridae

Hyaenidae

Herpestidae

Eupleridae

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Caniformia

Amphicyonidae† 

Canidae

Arctoidea

Hemicyonidae† 

Ursidae

Pinnipedia

Enaliarctidae† 

Phocidae

Otariidae

Odobenidae

Musteloidea

Ailuridae

Mephitidae

Procyonidae

Mustelidae

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References

[1] Eizirik, E., W.J. Murphy, K.P. Koepfli, W.E. Johnson, J.W. Dragoo, R.K.Wayne, en S.J. O’Brien, 2010. Pattern and timing of the

diversification of the mammalian order Carnivora inferred from multiple nuclear gene sequences. Molecular Phylogenetics and Evolution 56:

49-63.

[2] W.E. Johnson,E. Eizirik, J. Pecon-Slattery,W.J. Murphy, A. Antunes, E. Teeling, S.J. O’Brien, 2006. The Late Miocene Radiation of Modern

Felidae: A Genetic Assessment. Science 311; 73-77.

External links

• High-Resolution Images of Carnivore Brains (http:/   /  web. archive. org/  web/  20061001235922/  http:/   / 

brainmaps. org/  index. php?p=datasets-species#carnivore)

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Image Sources, Licenses and Contributors 12

Image:Procyon lotor 2.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Procyon_lotor_2.jpg  License: GNU Free Documentation License Contributors: BS Thurner Hof, Deadstar,

Till.niermann, 1 anonymous edits

File:Meles meles borz.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Meles_meles_borz.jpg License: Attribution Contributors: Kókay Szabolcs

File:Velvet the polecat.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Velvet_the_polecat.jpg License: Creative Commons Attribution 2.0 Contributors: Peter Trimming

File:Mustela Erminea head.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Mustela_Erminea_head.jpg  License: Creative Commons Attribution-Sharealike 2.0 Contributors: Keven

Law from Los Angeles, USA

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