Fossils
This type of fossil forms when minerals replace the original material of something that was once alive, such as a tree trunk.
Mineralized fossil
This eighteenth- and nineteenth-century idea held that each kind of organism remained essentially the same rather than changing into entirely different kinds.
Fixity of species
This molecule carries the genetic instructions used by living organisms.
DNA
This dating method places rocks or fossils in order from older to younger without necessarily assigning an exact numerical age.
Relative dating
These are anatomical features that have similar underlying structures in different organisms and are interpreted by evolutionists as evidence of shared ancestry.
Homologous structures
These preserved remains or traces of organisms provide clues about plants and animals that lived in the past.
Fossils
This naturalist proposed the theory of natural selection after studying variations among living organisms.
Charles Darwin
These changes in an organism's genetic material can introduce new variations into a population.
Mutations
This type of dating estimates a numerical age using measurements such as radioactive decay.
This field studies the early developmental stages of organisms, including embryos.
Embryology
When scientists discover fossils of organisms that no longer exist today, they are observing this biological event.
Extinction
According to this theory, organisms with traits that help them survive and reproduce are more likely to pass those traits to their offspring.
Natural selection
In natural selection, organisms with helpful inherited traits are more likely to do this, allowing those traits to become more common in a population.
Survive and reproduce
This radioactive form of carbon is commonly used to estimate the age of relatively recent remains that were once alive.
Carbon-14
These are structures that evolutionists interpret as reduced remnants of features that served a function in ancestors.
A fossil is discovered above a rock layer believed to be 50 million years old. Based on the relative positions of the layers, the fossil would generally be considered this in relation to that layer.
Younger
This theory, associated with Jean-Baptiste Lamarck, proposed that traits acquired during an organism's lifetime could be passed to its offspring.
Theory of acquired characteristics
These differences in genetic information help explain why individuals within the same population may have different characteristics.
Genetic variation
This principle states that, in an undisturbed sequence of sedimentary rock layers, the lower layers are generally older than the layers above them.
Principle of superposition
Evolutionists use this term for a hypothetical ancestral organism from which two or more groups of organisms descended.
Common ancestor
Petrified wood, preserved footprints, and mineralized bones are all examples of this broad category of evidence used to study ancient life.
Fossil evidence
This modern evolutionary framework combines genetics, mutations, and natural selection to explain changes in populations over generations.
Modern synthesis
This process allows organisms with helpful inherited traits to become more common in a population over many generations.
Natural selection
Scientists must make assumptions about starting conditions and decay rates when using radioactive dating. These assumptions are important because they affect this part of the dating process.
These proposed intermediate organisms are expected by evolutionary theory to show combinations of features associated with earlier and later groups.
Transitional forms