Fossil Evidence
The preserved remains or traces of organisms that provide evidence about past life.
Fossils
Tiktaalik had fish-like fins but also early versions of these structures found in tetrapods
Wrist bones / limb bones
The study of the distribution of organisms around Earth.
Biogeography
Structures that are reduced and no longer serve their original function.
Vestigial structures
The molecule that stores genetic information and provides evidence of relatedness between organisms.
DNA
The collection of fossils found in layers of rock that shows the history of life.
Fossil record
A fossil snake discovered with hip bones and hindlimbs provided evidence of a connection between snakes and these animals.
Lizards
Darwin used these islands’ unique finches and tortoises as evidence for evolution
Galápagos Islands
The human tailbone is an example of this type of structure.
Vestigial structure
All organisms use the same DNA triplet code and the same number of these building blocks to make proteins.
20 amino acids
Fossils that show characteristics of two different groups and provide evidence of evolutionary transitions.
Transitional fossils
Fossils such as Ambulocetus and Rodhocetus provide evidence that whales evolved from these types of ancestors.
Land-dwelling hoofed mammals
When unrelated species evolve similar adaptations because they live in similar environments
Convergent evolution
Structures with similar anatomy because they were inherited from a common ancestor.
Homologous structures
Genes involved in animal development that are shared from worms to humans.
Hox genes
This fossil had both reptile-like traits (teeth and a long tail) and bird-like traits (feathers and wings).
Archaeopteryx
Ambulocetus was likely able to do both of these activities.
Walk on land and swim
The reason island species often differ from mainland species.
Geographic isolation
Bird wings and insect wings are examples of structures with the same function but different origins.
Analogous structures
A protein used in the electron transport chain that scientists compare between organisms to determine relatedness.
Cytochrome c
This “fishapod” fossil showed a transition between fish and four-legged animals.
Tiktaalik roseae
The existence of transitional fossils supports the idea that evolution occurs through this process.
Gradual modification of existing traits
The separation of continents and islands allows populations to evolve independently through this process.
Isolation and speciation
The similar bone arrangement in the forelimbs of humans, bats, whales, and horses provides evidence of this.
Common ancestry
Humans and monkeys differ by only this many amino acids in cytochrome c
1 amino acid