Bears Amy, Lydia, Danielle, Rylee.

Ancestors Bears come from the family ursidae. The family ursidae is one of the nine families of Caniforms ( dog like carnivores) The bears closest relative is the pinniped, which is a seal like animal. Another close relative is the Canidae (Foxes, wolves, dogs) The Canidae is the last sub family that has survived to this day from Oligocene time period. Carnivores evolved in north America out of the members of the Maicidae family almost 42 million years ago. They soon split into two groups, A cat like group and A dog like group.

Muskleoskeletal  Bears have big strong stomachs that hold lot of food to store over the winter, all the food creates fat that keeps them warm. Their ancestors, seals, also have these fat stomachs.  Sloth bears have a certain head and tooth structure that allow them to eat termites, their main source of food.  Polar bears have small ears so it minimizes the amount of water that enters their ears when they are swimming and also so it prevents freezing in the inner ear.  Bears have a muscle hump over the shoulder is for catching large prey.  Bears have developed big paws that helps them swim, with claws to help catch prey.  Male polar bears grow 2 to 3 times the size of females.  Male Bears can weigh from about 772 to more then 1,433lbs. They are about ft long.  Female bears weigh about lbs and are roughly 6-8.2ft long.  Polar bears have a thick layer of black skin under their fur that brings in heat from the sun.

Agents of evolutionary change  Canadians are becoming part of the grizzly bear gene flow, as they put in a bear crossing on the Trans Canada Highway in order to improve gene flow. Because grizzlies are coming dangerously close to extinction.  Hair samples came back to show that mating was up since the crossing was put in place.  Black bears have claws for climbing, whilst brown, or grizzly bears have claws specifically for crushing plant material (as they are herbivores)  Polar Bears developed partially webbed feet over time because they have began to swim, and have a large diet of fish.  Earlier bears had to survive only on bamboo, their stomachs developed lining and their esophagus's changed so that they could digest the bamboo properly. The bears that didn’t adapt to digest the bamboo died out.

Evolutionary and cultural changes  The forest that most bears live in are the reason bears have adapted to hibernating in the winter. These forests have deciduous trees, that lose there leaves in the winter making it very cold. So as a result bears changed to their environment.  These forests they live in have rivers or water sources that they can easily access for fish, the main part of their diet.  200,000 years ago the ice age made thousands of bears extinct, as they evolved into polar bears for their new environment.  Modern brown bears first appeared in Asia then made their way to north america. (ursus americanus)  Natural selection is evident in polar bears, and their mutations has helped them survive in the Arctic.  The arctodus simus was found in southern California also known as the giant short faced bear who may have been the largest bear of species  The ursus spelaus (cave bear) was discovered extinct in Europe, its name comes from their fossils found in caves, these bears full skeletons were only found in caves.

DNA  Evolution of a bear began while cells in the nucleus started mutating causing positive and negative traits. The nitrogen base pairs were falsely matched up causing mutations.  For example the grizzly bear had a mutation of white fur, which evidently was advantageous to its new environment, this new trait survived as they mated and the old trait died off in that area.

Sources     adaptations-diagram/ adaptations-diagram/  bears/physical-characteristics/ bears/physical-characteristics/   ancestors-irelandhttp:// ancestors-ireland