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Systematics

The field focused on figuring out who's who and what is what, using multiple lines of evidence (fossils, DNA, morphological characters) to name, label, and group organisms.

Synapomorphy

A shared derived character; a character that is shared by members of a group due to inheritance from a common ancestor and has changed from the ancestral state; used to define monophyletic groups.

Monophyletic group

A group consisting of a common ancestor and all its descendants.

Paraphyletic group

A group that includes the most recent common ancestor and some, but not all, of its descendants.

Polyphyletic group

A group formed from lineages that do not share a recent common ancestor within the group.

Binomial nomenclature

A species name composed of two parts, Genus and species epithet: Genus capitalized and species lowercase; italics are typically used in proper formatting.

Homologous characters

Characters derived from a common ancestor; may appear differently due to divergence (e.g., forelimb bones in tetrapods).

Analogous characters

Characters similar in function due to convergent evolution but not derived from a common ancestor (e.g., wings in bats vs birds).

Trace fossils

Fossils such as footprints, tracks, nests, and burrows that record behavior and locomotion, providing insights into paleoecology.

Tiktaalik

A key transitional form between fish and true land tetrapods, possessing both amphibian-like and fish-like features, highlighting the fish-to-tetrapod transition.

Systematics

The field focused on figuring out who's who and what is what, using multiple lines of evidence (fossils, DNA, morphological characters) to name, label, and group organisms.

Synapomorphy

A shared derived character; a character that is shared by members of a group due to inheritance from a common ancestor and has changed from the ancestral state; used to define monophyletic groups.

Monophyletic group

A group consisting of a common ancestor and all its descendants.

Paraphyletic group

A group that includes the most recent common ancestor and some, but not all, of its descendants.

Polyphyletic group

A group formed from lineages that do not share a recent common ancestor within the group.

Binomial nomenclature

A species name composed of two parts, Genus and species epithet: Genus capitalized and species lowercase; italics are typically used in proper formatting.

Homologous characters

Characters derived from a common ancestor; may appear differently due to divergence (e.g., forelimb bones in tetrapods).

Analogous characters

Characters similar in function due to convergent evolution but not derived from a common ancestor (e.g., wings in bats vs birds).

Trace fossils

Fossils such as footprints, tracks, nests, and burrows that record behavior and locomotion, providing insights into paleoecology.

Tiktaalik

A key transitional form between fish and true land tetrapods, possessing both amphibian-like and fish-like features, highlighting the fish-to-tetrapod transition.

Cladogram

A diagram that depicts evolutionary relationships among groups of organisms, typically structured as a branching tree showing clades.

Outgroup

A species or group of species that is closely related to the group of organisms being studied (the ingroup), but which diverged before the ingroup; used to infer ancestral character states.

Character state

The particular condition or value of a character within a taxonomic analysis (e.g., for the character 'petal color', the states could be 'red', 'blue', 'white').

Homoplasy

A character shared by a set of species but not present in their common ancestor, often due to convergent evolution, parallel evolution, or character reversal; leads to analogous features.