Paper No. 76-40
Presentation Time: 9:00 AM-5:30 PM
ARE DEAD CLADE WALKING VICTIMS OR SURVIVORS?
Jablonski (2002) introduced the concept of dead clade walking (DCW) as a taxon that persists through a mass extinction but does not undergo post-recovery diversification. Here we examine three questions regarding DCW: (1) One could argue that DCW are ultimately victims of a mass extinction, even though they initially survive the event. If we consider DCW to be victims rather than survivors, how are macroevolutionary analyses affected? (2) Based on characteristics observable before an extinction event, are DCW are more similar to survivors or victims of mass extinctions? (3) Based on characteristics observable after an extinction event, are DCW are more similar to boundary-crossing survivors or newly-originated taxa? First, we find that analyses of extinction risk are not substantially affected by the classification of DCW as survivors or victims, due to the relative scarcity of DCW. Second, using principal component analysis, we find that it is difficult to distinguish between DCW and other taxa, except in the Late Permian (Tatarian stage), in which DCW more closely resembled mass extinction survivors. Third, in the Scythian stage immediately following the end-Permian mass extinction, DCW are distinguished from survivors by a lower geographic range or abundance. We conclude that DCWs are similar to other mass extinction survivors, but were hit harder by the extinction.