phylogeny, fossils and the history of life

Phylogeny

the evolutionary history and relationships among species or groups of organism

phylogenetic tree

a diagram that represent evolutionary relationships based on shared ancestry

node

a point on a phylogenetic tree where a common ancestor give rise to descent lineages

sister group

two taxa or lade that share an immediate common ancestor; each others closets relatives

taxa

groups of organism classified together

monophyletic

a group consisting of a common ancestor and all its descendents

clade

a monophyletic group- an ancestor and all its descendants

paraphyletic

a group that includes a common ancestor by not all its descendants

polyphyletic

a group that does not include the most recent common ancestor of all members

genus

a taxonomic rank above species; groups closely related species

family

a taxonomic rank above genus; groups related genera

order

a rank above family; groups related families

class

rank above orders, groups related orders

Phylum

a rank above class groups related classes

kingdom

a high taxonomic rank grouping related phyla

Domain

the higher taxonomy rank

character

a heritable trait or feature to study evolutionary relationships

character state

a specific version of a character

homologous

traits that are similar because they where inherited from a common ancestor

Homology

the evolutionary relationship that explains homologous traits

Analogous

traits that are similar due to convergent evolution, not shared ancestry

analogy

the functional similarity that arises when unrelated species evolve similar traits independently

synapomorphy

a shared, derive character that defines clade

cladistics

a method of classifying organism based on shared, derived traits

out group

a species or group used for comparison that is outside the group being studied; helps determine what traits are ancestral

parsimony

the principle that the simplest explaination- requiring the fewest evolutionary changes is preferred when building phylogenetic trees

trace fossil

evidence of an organisms activity ( footprints, burrows ) rather than persevered body parts

molecular fossils

chemical traces or biomolecules preserved in ancient rocks, reflecting past life

geologic timescale

a timeline of earths history divided into eons, eras, period, and epochs based on major biological and geological events

radiometric dating

a method for deterring that age of rocks or fossils by measuring the decay of radioactive isotopes

half life

the time is takes for half of the atom in a radioactive isotopes to decay

mass extinction

a sudden, widespread loss of many species across the planet in a relatively short geological time

cambrian explosion

a rapid burst of evolutionary diversification around 540 millions years ago, when most major animal groups first appear in the fossil record