@Bear #bear

BearWild Animal

Bears are carnivoran mammals of the family Ursidae. They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Northern Hemisphere and partially in the Southern Hemisphere.

Family: Ursidae; G. Fischer de Waldheim, 1817

Speed: Polar bear: 40 km/h

Scientific name: Ursidae

Lifespan: Giant panda: 20 years

Mass: Polar bear: 450 kg, Giant panda: 70 – 100 kg, MORE Encyclopedia of Life

Height: Polar bear: 1.8 – 2.4 m, Giant panda: 60 – 90 cm, Brown bear: 70 – 150 cm



Biology Of Bear
Evolution
The earliest members of Ursidae belong to the extinct subfamily Amphicynodontinae, including Parictis (late Eocene to early middle Miocene, 38–18 Mya) and the slightly younger Allocyon (early Oligocene, 34–30 Mya), both from North America.

These animals looked very different from today's bears, being small and raccoon-like in overall appearance, with diets perhaps more similar to that of a badger. Parictis does not appear in Eurasia and Africa until the Miocene.

It is unclear whether late-Eocene ursids were also present in Eurasia, although faunal exchange across the Bering land bridge may have been possible during a major sea level low stand as early as the late Eocene (about 37 Mya) and continuing into the early Oligocene.

European genera morphologically very similar to Allocyon, and to the much younger American Kolponomos (about 18 Mya), are known from the Oligocene, including Amphicticeps and Amphicynodon.

There has been various morphological evidence linking amphicynodontines with pinnipeds, as both groups were semi-aquatic, otter-like mammals.

In addition to the support of the pinniped–amphicynodontine clade, other morphological and some molecular evidence supports bears being the closet living relatives to pinnipeds

Phylogeny
The bears form a clade within the Carnivora. The cladogram is based on molecular phylogeny of six genes in Flynn, 2005.

There are two phylogenetic hypotheses on the relationships among extant and fossil bear species. One is all species of bears are classified in seven subfamilies as adopted here and related articles: Amphicynodontinae, Hemicyoninae, Ursavinae, Agriotheriinae, Ailuropodinae, Tremarctinae, and Ursinae.

Below is a cladogram of the subfamilies of bears after McLellan and Reiner (1992) and Qiu et al. (2014):

Size
The bear family includes the most massive extant terrestrial members of the order Carnivora. The polar bear is considered to be the largest extant species, with adult males weighing 350–700 kg (772–1,543 lb) and measuring 2.4–3 metres (7 ft 10 in–9 ft 10 in) in total length.

The smallest species is the sun bear, which ranges 25–65 kg (55–143 lb) in weight and 100–140 cm (39–55 in) in length. Prehistoric North and South American short-faced bears were the largest species known to have lived.

The latter estimated to have weighed 1,600 kg (3,500 lb) and stood 3.4 m (11 ft) tall. Body weight varies throughout the year in bears of temperate and arctic climates, as they build up fat reserves in the summer and autumn and lose weight during the winter.

Morphology
Bears are generally bulky and robust animals with short tails. They are sexually dimorphic with regard to size, with males typically being larger.

Larger species tend to show increased levels of sexual dimorphism in comparison to smaller species. Relying as they do on strength rather than speed, bears have relatively short limbs with thick bones to support their bulk.

The shoulder blades and the pelvis are correspondingly massive. The limbs are much straighter than those of the big cats as there is no need for them to flex in the same way due to the differences in their gait.

The strong forelimbs are used to catch prey, to excavate dens, to dig out burrowing animals, to turn over rocks and logs to locate prey, and to club large creatures. Despite being quadrupeds, bears can stand and sit as humans do.

Unlike most other land carnivorans, bears are plantigrade. They distribute their weight toward the hind feet, which makes them look lumbering when they walk.

They are capable of bursts of speed but soon tire, and as a result mostly rely on ambush rather than the chase. Bears can stand on their hind feet and sit up straight with remarkable balance.

Their front paws are flexible enough to grasp fruit and leaves. Bears' non-retractable claws are used for digging, climbing, tearing, and catching prey.

The claws on the front feet are larger than those on the back and may be a hindrance when climbing trees; black bears are the most arboreal of the bears, and have the shortest claws.

Pandas are unique in having a bony extension on the wrist of the front feet which acts as a thumb, and is used for gripping bamboo shoots as the animals feed.