Eldredge, Niles.2014-12-092014-12-091971http://dx.doi.org/10.5531/sd.paleo.5http://hdl.handle.net/2246/6565Three-dimensional sketch contrasting a pattern of relative stability (A) with a trend (B), where speciation (dashed lines) is occurring in both major lineages. Morphological change is depicted here along the horizontal axes, while the vertical axis is time. Though a retrospective pattern of directional selection might be fitted as a straight line in (B), the actual pattern is stasis within species, and differential success of species exhibiting morphological change in a particular direction.enPunctuated equilibria (Evolution)Other