Loading AI tools
Two extinction intervals that occurred during Stages 4 and 5 of the Cambrian Period From Wikipedia, the free encyclopedia
The end-Botomian mass extinction event, also known as the late early Cambrian extinctions, refer to two extinction intervals that occurred during Stages 4 and 5 of the Cambrian Period, approximately 513 to 509 million years ago. Estimates for the decline in global diversity over these events range from 50% of marine genera[1] up to 80%.[2] Among the organisms affected by this event were the small shelly fossils, archaeocyathids (an extinct group of sponges), trilobites, brachiopods, hyoliths, and mollusks.[1][3][4][5]
There are several hypotheses for the causes of these extinctions. There is evidence that major changes in the carbon cycle[6][7][8][9] and sea level occurred during this time.[1][10] Evidence also exists for the development of anoxia (a loss of oxygen) in some environments in the oceans.[1][11][12]
One hypothesis that unifies this evidence links these environmental changes to widespread volcanic eruptions caused by the emplacement of the Kalkarindji Large Igneous Province or LIP.[13][14] These widespread eruptions would have injected large amounts of greenhouse gases into the atmosphere causing warming of the climate and subsequent acidification and loss of oxygen in the oceans.[13] Mercury anomalies have been discovered in strata corresponding to the extinction event; however, such enrichments in mercury are also found in older rocks that predate the biotic crisis.[15] The precise timing between the eruptions and the extinction events remain unresolved.[14]
Seamless Wikipedia browsing. On steroids.
Every time you click a link to Wikipedia, Wiktionary or Wikiquote in your browser's search results, it will show the modern Wikiwand interface.
Wikiwand extension is a five stars, simple, with minimum permission required to keep your browsing private, safe and transparent.