Comparative Anatomy

Fossils are evidence of past life. They can be preserved in different forms like rock, amber, ice, and petrified wood.

Animals become extinct when there are no more left of their species on Earth. After animals are extinct, fossils provide evidence they once existed.

Organisms become extinct for different reasons. Most commonly, they become extinct because they no longer have the ability to acquire the necessary resources (food, water, mates) to survive long enough to reproduce and have more young.

Adaptations are changes in populations of organisms over time. Those changes are a result of some organisms within the population having characteristics that increase the likelihood they will survive to reproductive age. Because of that, those characteristics become more common over time, thus increasing in number in the population.

Changes in the environment will affect many things about how an organism lives, specifically its access to resources. Environmental changes resulting from natural disasters or other occurrences cause certain characteristics to be most favorable for survival.

Populations that do not change over time in response to environmental changes will eventually become extinct. After extinction occurs, the only evidence existing of those previous life forms are fossils. Fossils are examined today in order to determine if prehistoric creatures are similar to more modern ones.

All bones in males and females are arranged in the same ways, but on average males have slightly wider shoulders and females have slightly wider pelvises.

Dogs, dolphins, bats, and humans all have a similar pattern in their upper arm bone structure—one big bone connected to two bones, connected to many bones, connected to finger-like bones.

Their bones have the same basic pattern, and their skulls connect directly to the spine.

They all start out as a single cell and develop the same pattern of structures such as tails and pharyngeal slits. Some of those structures remain as the embryo gets older, but others go away.

Horses, whales, snakes, birds and more have evolved!

They study how living things grow from a single cell to highly complex organisms.