Introduction: -Organism: American Black Bear(common name) or also called Ursus americanus. -Description: Smallest of the three bears species found in North America. They have short, non-retractable claws that give them an great tree climbing ability. -Classification: kingdom: animal, phylum: chordata, class: mammal, Order: carnivores, Family: bear, Genus: Ursus, Species: americanus. -Habitat Description: They are primarly found in forested areas with thick ground vegetation. They can also be found in fields or meadows,they live in Canada. There are about 396,000-476,000 american black bears.
Morphological and Molecular Evidence: Closest relatives: 1. Grizzly bears: they look very similar, grizzly bears typically weigh more, black bears are not as aggressive as grizzly bears. 2. Sun bears: They basically have the same fur color, range around 6ft tall so, similar in height, follow around same diet. 3. Asiatic Bear: They are not found near each other but, if you saw them you would not be able to see the difference because, of how similar they look from each other.
Ancestors of American Black bears diverged from sun bears. First fossil of evidence of american black bears was in Port Kennedy, Pennsylvania.
Homologous Sturctures: -Comparison Organisms: Elephants: limbs are used to hold structure in legs, Humans: limbs are used in ones arms, Sea lions: limbs are used to swim in water. Homologous structures are body parts with the same basic structure and embryonic organism, though not necessarily sharing the same function as each other. The structures in bears are shared by related organisms that were inherited from a common ancestor.
Vestigial Structures: -Fur: They use fur to keep themselves warm, but if they hide in caves and hibernate do they really need fur?-Claws: Claws are used for defense and to dig in the dirt but, if they are already tall do they really need claws to defend themselves?-Sense of Smell: Bears have an excellent sense of smell to smell their predators around them but, if they have ears to listen to prey do they need a excellent sense of smell? Vestigial Structures are structures that have no apparent function and appear to be residual parts from a past ancestor.
Transitional Fossils: -Recent Ancestor: Pinnipeds are in the same group as bears, which both are dog-like species, also have non-retractile claws, a difference is that bear species are bigger in size. Canids: similiarites: 4 legs/ same structure, can be found in cold areas. Musteliods: -similar diet also, both are mammals. A transitional fossil is any fossil, which, gives information about a transition from one species to another.