Tremarctos

Tremarctos Temporal range: Pliocene - Recent,
Spectacled bear, Tremarctos ornatus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Ursidae
Subfamily:	Tremarctinae
Genus:	Tremarctos Gervais, 1855
Type species
Tremarctos ornatus Cuvier, 1825
Species
†Tremarctos floridanus (Gildey, 1928) Tremarctos ornatus (Cuvier, 1825)

Tremarctos is a genus of the monophyletic bear subfamily Tremarctinae, endemic to Americas from the Pliocene to recent. The northern species, the Florida short-faced bear, became extinct 11,000 years ago. The sole living Tremarctos species is the South American spectacled bear. Tremarctos is also the only living genus under the Tremarctinae subfamily, with the other genera, Plionarctos, Arctodus, and Arctotherium all being extinct.

Species

• †Tremarctos floridanus - Florida short-faced bear
• Tremarctos ornatus - spectacled bear

Habitat

Tremarctos floridanus bears lived in the southern parts of North America. Tremarctos ornatus however lives in South America, such as in the Andes Mountains of Peru. They also live in countries like Bolivia and Venezuela. Tremarctos orantus is the only species of bear to live in South America. They like to build nests that they use to sleep and eat in, in trees of high elevation in humid tropical rain forests. They are able to live in other types of biomes too such as temperate grasslands, deciduous forests, and more. Where they choose to live is dependent upon the type of food/resources that are available in the habitat.

Diet

The diet of Tremarctos bears is varied. They are considered omnivores as they eat fruit, corn, plants, insects, farm animals, and more.

Species under this genus are able to use their paws to manipulate food. They can strip leaves off of trees, pick apart fruits, grasp food, etc. They do this with the help of having a radius sesamoid, also referred to as a "false thumb".

Hunting and eating take up most of a Tremarctos bears activity levels. Tremarctos bears are diturnal meaning that they will hunt during either the day, evening, or night, meaning they do not hibernate. It depends on where the bear is located and what the current season is that determines when they are the most active.

Etymology

The genus name Tremarctos was created in 1855 by Alfred Gervais. While his suggestion for making Tremarctos a separate genus was rejected, after further studies comparing skeletal structures of the teeth and jaws of Tremarctos to other bear species his suggestion was later then accepted.

The word Tremarctos is derived from the Greek language and translates to "hole bear" in English. If one were to look at humerus of this type of bear, one would notice a hole in the middle of it. This is where its name comes from and why it is called the "hole bear". However, the name "hole bear" could also come from the fact that the tan facial markings appear on the face except around the bear's eyes, making it look like the bear has holes for eyes, giving it the Jukumari in the Andean culture.

Physical Characteristics

Size

Species under the Tremartcos genus are about average-sized bears, similar in size to the American Black Bear. They can weigh anywhere from 150 to 400 lbs. The Tremarctos Floridanus however, was bigger than Tremarctos Orantus. Both species are sexually dimorphic, meaning the males are most times larger than the females in size. This also results in the males having protein blood levels higher than the females' levels. The forelimbs of Tremarctos bears are longer than their hindlimbs.

Morphology

They have long curved claws and have plantigrade feet. As for their fur, they are usually black with a tannish marking that extends from their chest to around their face. While Tremarctos Floridanus's exact appearance is unknown, they presumably resembled the Tremarctos Ornatus. Although they have large, deep skulls, they are the smallest in length among the bear species.

Dentation

The species under the Tremarctos genus have short mandibles as well as short crania. Even though they are omnivores, the evidence of having short mandibles and crania indicates they feed mostly on plants and fruits and only sometimes eat meat. Because of this they also have resilient teeth near their cheeks. They also have small canines and large molars showing they eat meat as well. They have 42 teeth.

Breeding

Courtship occurs between male and female Tremarctos bears and this usually involves vocalizations or playful fighting. Tremarctos are polygamous meaning the male bears breed with multiple female bears. They are also polyesterous, meaning the bears have specific breeding seasons with twins being the most common litter. Cubs are usually born during seasons when fruits and vegetables are growing and becoming ripe.

The mothering bears create dens for raising their offspring. When the cubs are born, their eyes are closed and they lack teeth. The mothers will care for the cubs for about three years and after which, they separate. Male Tremarctos bears tend to live longer than females.

Threats

While the Tremarctos bear is higher up on the food chain, it still has a couple of predators and other things that threaten them. With Tremarctos floridanus extinct, Tremarctos ornatus is the only living species of this genus, their population is slowly declining and they are considered vulnerable on the Threatened Species List. One of the biggest reasons for their decline is due to humans poaching and causing their habitat loss. In some locations they encounter predators such as jaguars and cougars. They are also susceptible to parasites such as ticks and nematodes as well as diseases such as alopecia and neoplasia.