Temporal range: 42–0Ma Eocene - Recent
|All extant land-dwelling caniform families (clockwise from top left): Canidae, Ursidae, Mephitidae, Mustelidae, Procyonidae, Ailuridae|
Caniformia, or Canoidea (literally "dog-like"), is a suborder within the order Carnivora. They typically possess a long snout and non-retractile claws (in contrast to the cat-like carnivorans, the Feliformia). The Pinnipedia (seals, and sea lions) evolved from caniform ancestors and are accordingly assigned to this group. Most members of this group have non-retractile claws (the fisher, marten, red panda and ringtail have retractile or semi-retractile claws) and tend to be plantigrade (with the exception of Canidae). Other traits that separate Caniformia from Feliformia is that caniforms have longer jaws and have more teeth, with less specialized carnassial teeth. They also tend more towards omnivorous and opportunistic feeding, while the feliforms are more specialized for eating meat. Caniforms have single-chambered or partially divided auditory bullae, composed of a single bone, while in feliforms the auditory bullae are double-chambered, composed of two bones joined by a septum. In the Canoidea, the penis is highly specialized.[further explanation needed]
The center of diversification for Caniformia is North America and Northern Eurasia with these regions having the most diversity of Caniforms. This contrasts the Feliforms whose center of diversification was in Africa and Southern Asia.
Caniformia consists of twelve families, with nine extant and three extinct. The extant Caniform families are monophyletic according to their molecular phylogeny. At one time, Hyaenidae (hyenas) were included, but genetic testing has shown them to belong in Feliformia instead. Terrestrial caniforms in the wild are found on all continents with the exception of Antarctica, while pinnipeds are distributed throughout the world's oceans.
The Family Canidae (canids, commonly known as either dogs or canines) includes wolves, dogs and foxes. They are the most social of all the caniforms, living in packs. The dog is the most diverse of all mammals in terms of body structure variants. The Canidae family is divided into the "true dogs" of the tribe Canini and the "foxes" of the tribe Vulpini. The two species of the basal Caninae are more primitive and don't fit into either tribe.
The Family Ursidae (bears) are the largest of all the land caniforms. They range from the large polar bear (males, 350–680+ kg or 775-1500+ lb) to the small sun bear (males, 30–60 kg or 66–132 lb) and from the endangered giant panda to the very common black bear. Common characteristics of modern bears include a large body with stocky legs, a long snout, shaggy hair, plantigrade paws with five nonretractile claws and a short tail. Most bears are omnivorous, with largely varied diets that include both plants and animals. The polar bear is mostly carnivorous due to the harsh climate in which it lives and shows a preference for eating seal, while the giant panda is mostly herbivorus and feeds almost entirely on bamboo, a fast-growing though tough and woody member of the grass family that the panda's powerful jaws are designed to crunch through. The sloth bear has the beginnings of adaptations towards ant and termite eating with a long snout, powerful claws, and missing upper front teeth though it will also eat honey and fruit.
The Family Ailuridae (red panda) was once thought to be either part of the Procyonidae or the Ursidae. It is now placed in its own family. It is found in the Himalayas, including southern China, Nepal, Bhutan, India and Pakistan; fossil species of the family also lived in North America.
The Family Mephitidae (skunks), once thought to be part of the Mustelidae, is now recognized as a group in its own right. There are 12 species of skunks, which are divided into four genera: Mephitis (hooded and striped skunks, two species), Spilogale (spotted skunks, four species), Mydaus (stink badgers, two species) and Conepatus (hog-nosed skunks, four species). The two skunk species in the Mydaus genus inhabit Indonesia and the Philippines; all other skunks inhabit the Americas from Canada to central South America.
The Family Mustelidae (badgers, weasels and otters) is the most diverse of the group. While highly variable in shape, size and behavior, most mustelids are smaller animals with short legs, short round ears and thick fur. Mustelids are predominantly carnivorous. While not all mustelids share identical dentition, they all possess teeth adapted for eating flesh, including the presence of shearing carnassials.
The Family Procyonidae (raccoons, coatis, etc.), are smallish animals, with generally slender bodies and long tails. Except for the kinkajou, all procyonids have banded tails and distinct facial markings and, like bears, are plantigrade, walking on the soles of their feet. Most species have non-retractile claws. It has been suggested that early procyonids were an offshoot of the canids that adapted to a more omnivorous diet.
The clade Pinnipedia (seals, sea lions, walruses) are a widely distributed and diverse group of semi-aquatic marine mammals descended from a common ancestor most closely related to modern bears. The group comprises three families:
- Phocidae: (true seals or earless seals) comprise around 19 species of highly aquatically adapted, barrel-shaped animals ranging from 45 kg (100 lb) and 1.2 m (4 ft) in length (the ringed seal), to 2,400 kg (5,300 lb) and 5 m (16 ft) (southern elephant seal). Phocids are found throughout the world's oceans.
- Otariidae: (the eared seals, including sea lions and fur seals) Distributed throughout the world's oceans with the exception of the North Atlantic, the 16 species of otariid are distinguished from the phocids by visible external ears (pinnae), more dog-like faces and the ability to turn their rear flippers forward.
- Odobenidae (the walrus is the only surviving member). A large (2,000 kg or 4,400 lb), distinctive pinniped with long whiskers and tusks, the walrus has a discontinuous circumpolar distribution in the Arctic Ocean and sub-Arctic seas of the Northern Hemisphere. It is primarily a benthic forager of bivalve mollusks and other marine invertebrates.
Caniforms first appeared as tree-climbing, superficially marten-like carnivores in the Eocene around 42 million years ago. Miacis cognitus was probably an early caniform. Like many other early carnivorans, it was well suited for tree climbing with needle sharp claws, and had limbs and joints that resemble those of modern carnivorans. Miacis cognitus was probably a very agile forest dweller that preyed on smaller animals, such as small mammals, reptiles and birds.
Recent molecular evidence suggests that pinnipeds evolved from a bearlike ancestor about 23 million years ago during the late Oligocene or early Miocene epochs, a transitional period between the warmer Paleogene and cooler Neogene period.
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