title: Oxygen and animal evolution: did a rise of atmospheric oxygen "trigger" the origin of animals?
abstract: Recent studies challenge the classical view that the origin of animal life was primarily controlled by atmospheric oxygen levels. For example, some modern sponges, representing early-branching animals, can live under 200 times less oxygen than currently present in the atmosphere - levels commonly thought to have been maintained prior to their origination. Furthermore, it is increasingly argued that the earliest animals, which likely lived in low oxygen environments, played an active role in constructing the well-oxygenated conditions typical of the modern oceans. Therefore, while oxygen is still relevant to understanding early animal evolution, the relationships between the two might be less straightforward than previously thought.
authors.affiliation: Department of Biology and the Nordic Center for Earth Evolution, University of Southern Denmark, Odense M, Denmark.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Mills
authors.forename: Donald E
authors.initials: DE
authors.lastname: Canfield
mesh_terms: D000818:Animals; D001272:Atmosphere; D005075:Biological Evolution; D004734:Energy Metabolism; D009792:Oceans and Seas; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D010126:Ozone / Q000032:analysis; D011161:Porifera / Q000502:physiology; D013816:Thermodynamics; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D010126:Ozone; D010100:Oxygen
keywords: Proterozoic; eukaryotes; geochemistry; hypoxia; marine oxygenation; metazoans