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The Order Carnivora
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The order Carnivora
can be found throughout the world, naturally occurring on all
continents except Australia, New Guinea, New Zealand, some oceanic
islands, and Antarctica, and are able to adapt to all major types of
habitats. There are between 240-270 recognized species in this
order, depending on the source. Some of these species have so
little information on them that they are discarded by some
sources. The carnivores consist of 15 living families in two
suborders: Caniformia, the
dog-like carnivores, and Feliformia,
the cat-like carnivores. There is an alternate classification
using the superfamilies Canoidea (or Arctoidea), and Feloidea
(or Aeluroidea), but the suborder classification is more widely
accepted. Classification in the Carnivora, as with most species,
is very controversial, and the placement of the taxons in their
respective orders, suborders, superfamilies, families, subfamilies and
even genus-species will vary between authorities. This site uses
the classification method listed at ITIS,
which is the standard in classifying species. However, taxon
placement will vary widely with source, so it is important to keep in
mind that no single classification of a species is "correct", and the
classification of the species in relation to each other and within
their phylogenic tree will continually change. In the Caniformia suborder, there are the families of Ailuridae (red panda), Canidae (dogs), Mephitidae (skunks and stink badgers) Mustelidae (weasels), Otariidae (eared seals and sealions), Odobenidae (walrus), and Phocidae (earless seals), Procyonidae (raccoons), Ursidae (bears), and the extinct families Amphicyonidae and Hemicyonidae (bear-dogs). The three aquatic carnivore families of seals, sealions and walrus were formerly classified in the order Pinnepedia. Some sources list Pinnepedia opposite Fissipedia as two suborders of Carnivores, although this classification is not widely accepted anymore. The family Mephitidae (skunks) have recently been split off of the Mustelidae group, although some sources still list them in this family. The placement of the genus Mydaus is still controversial. Ailuridae is the accepted family of a single species, the red panda (Ailurus fulgens), although some sources still list the red panda with the Procyonidae family. This suborder is sometimes broken down into superfamilies, such Carnivores in this superfamily are characterized by having a non-chambered or partially chambered auditory bullae, non-retractable claws, and well-developed baculum. With a few exceptions, most species are simply colored, lacking the flashy spotted or rosetted coats of many species of felids and viverrids. This is because these species tend to range in the temperate and subarctic biomes. Mustelidae and Procyonidae have a few tropical species. Although a few species, notably the procyonids, are arboreal, most are terrestrial. All families except the Canidae and a few species of Mustelidae are plantigrade. Diet is varied, and most species tend to be omnivorous to some degree, and thus the carnassial teeth are less specialized. Animals in this superfamily have more teeth, notably the premolars and molars, in an elongated skull. In the Feliformia suborder, there is the families of Eupleridae (Malagasy carnivores), Felidae (cats), Herpestidae (mongooses), Hyaenidae (hyenas), Nandiniidae (African palm civet), and Viverridae (civets), as well as the extinct family Nimravidae (paleofelids). Some sources place the herpestids and viverrids in the same family; however, there are significant morphological and behavioral differences between the two groups, enough to warrant them being placed in their own respective families rather than lumped together under Viverridae. The Malagasy carnivores have recently been removed from their former families and placed into their own family, Eupleridae, based on morphological and genetic differences. Nandiniidae consists of a single species, the African palm civet (Nandinia binotata), although many sources still place this species within the family Viverridae. Carnivores in the Feloidea superfamily have a two-chambered auditory bullae. Many species have spotted, rosetted or striped coats, and tend to be more brilliantly colored than their Canoidean counterparts. This is due to the fact that these species tend to range in tropical habitats, although a few species do inhabit temperate and subarctic habitats. Quite a few of these species are arboreal or semi-arboreal. The majority of these species are digitigrade, with very few exceptions. Diet tends to be more strictly carnivorous, especially in the Felidae family. These species have fewer teeth and shorter skulls, with much more specialized carnassials meant for shearing meat. Though generally medium-sized mammals, the carnivores can range in size from the least weasel (Mustela nivalis), which weighs 35-70 grams (1-2 oz.), to the Kodiak brown bear (Ursus arctos), which can weigh up to 780 kg (1700 lb). All members of the order Carnivora have a specialized fourth upper premolar, the carnassial pair. These teeth are large, and fit together with the lower first molar to create a shearing mechanism. These teeth are the most highly developed in the Felidae and are least developed in the Ursidae. They have six incisors and two conical canines in each jaw. The only two exceptions 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. It is the number of molars and premolars which is variable between species. All teeth are deeply rooted and are diphyodont. The jaws of carnivores can only move on a vertical axis, in an up-and-down motion, and cannot move from side-to-side. They have relatively large brains encased in a heavy skull. The skull has a highly developed zygomatic arch, sagittal crest, and ossified external auditory bullae. Carnivores 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, absent in some. Carnivores have very acute, highly-developed senses, especially vision and hearing. Most carnivores hunt their prey using stealth, but a few, like the cheetah (Acinonyx jubatus) use speed to outrun their prey. Carnivores 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. Most species of carnivores are, to some degree, omnivorous, except the Felidae, which are obligate carnivores. Carnivora tend to produce a single litter annually, but some produce multiple litters a year, and larger carnivores like bears have gaps of 2-3 years between litters. The average gestation period lies between 50-115 days, although the ursids and mustelids have delayed implantation, thus extending the gestation period 6-9 months beyond the normal period. Litter sizes are usually small, ranging from 1-13 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 carnivores are solitary, but a few are gregarious. The family Carnivora arose from the miacids, a weasel-like animal that lived in the Paleocene, approximately 60 million years ago (mya). The miacids themselves arose from weasel-like insectivores during the late Cretaceous. The miacids divided into two groups, the Miacidae and Viverravidae, the difference being that Viverravidae had specialized carnassials and fewer molars. There was another order of carnivores that existed during this period, the Creodonta, though they did not give rise to the modern carnivores, and instead became extinct in the early Pliocene (4-5 mya). In the Eocene (48 mya), the two main branches of Carnivora arose: the Caniformia and Feliformia. Based on dental morphology, the Caniformia resembles the Miacidae, and the Feliformia resembles the Viverravidae. The Nimravidae (sabre-toothed cats) in the Feliformia group, and the Amphicyonidae (bear-dogs) in the Caniformia group, became extinct in the Pliocene (4-5 mya), along with the Creodonts. Traditionally, the two groups Miacidae and Viverravidae were classified in an extinct superfamily, Miacoidea. Now, however, both Carnivora and Miacoidea are classed in the clade Carnivoramorpha, and Miacoidea are regarded as basal carnivoramorphs. This clade excludes Creodonts.
Classification of the Order Carnivora:
Alternate taxonomic trees can be found at Mikko's Archive at at Systema Natura. Links:
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