Range offset

In geology, range offset is the time difference between the last fossil occurrence of a taxon and the actual disappearance of this taxon. Range offset can be used as a measure of biostratigraphic precision and determines among others how much information about extinctions can be derived from fossil occurrences.
Definition.
The range offset of a taxon is defined as 
Effects of sequence stratigraphy.
Range offset is strongly affected by sequence stratigraphy. Simulations show that range offset changes by up to three orders of magnitude dependent on the position in the systems tracts.