Phylogeny and Evolutionary History

Flashcards covering key concepts related to phylogeny, mass extinctions, and evolutionary history.

Phylogeny

Shows relationships among organisms.

Monophyletic group

An ancestor and all of its descendants on one branch of phylogeny.

Paraphyletic group

An ancestor and only some of its descendants.

Sister Groups/Sister Taxa

Two descendants that split from a common node in a phylogeny and are each other's closest relatives.

Mass Extinction

An event in which at least 50% of species die out within 1 million years.

Cambrian Explosion

About half a billion years ago, the first occurrence of hard body parts in organisms.

Aerobic Metabolism

Life-sustaining process using oxygen, developed shortly before 2 billion years ago.

First fossil evidence of life

Discovered from 3.8 billion years ago, indicating the presence of prokaryotic cells.

Modern Systematists

Biologists who believe that a group shouldn't have a classification unless it is monophyletic.

Extinction rates in modern times

Similar to those in past mass extinctions, leading to discussions of a potential 6th mass extinction.