Dead clades walking

Dead Clade Walking

The phrase Dead Clade Walking refers to the fact that some clades (groups) of organisms which survive mass extinctions either become extinct a few million years after the mass extinction or fail to recover in numbers and diversity.

The phrase "Dead Clade Walking" was coined by David Jablonski (2002) as a reference to Dead Man Walking, a film whose title is based on USA prison slang for a condemned prisoner's last walk to the execution chamber.

Jablonski found that the extinction rate of marine invertebrates was significantly higher in the stage (major subdivision of an epoch - typically 2-10M years duration) following a mass extinction than in the stages preceding the mass extinction. His analysis focused on marine mollusks since they constitute the most abundant group of fossils and are therefore the least likely to produce sampling errors. Jablonski suggested that two possible explanations deserved further study:

  • Post-extinction physical environments differed from pre-extinction environments in ways which were disadvantageous to the "dead clades walking".
  • Ecosystems that developed after recoveries from mass extinctions may have been less favorable for the "dead clades walking".

References

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