Comments on the Manhattan stratigraphic measure

The Manhattan stratigraphic measure was proposed as a measure of congruence between temporal information retrieved from the fossil record and a phylogenetic hypothesis. This index is based on the fit of a Sankoff character representing the stratigraphic ages of terminal taxa and is calculated in a way analogous to the consistency index. Sample cases are analyzed in which this measure is insensitive to increasing amounts of conflict between stratigraphic and topological temporal information. A simple modification of the step matrix upon which the measure is based is proposed. The modified index, MSM*, overcomes the observed problem and is based on the measurement of the number and extent of ghost lineages. (C) 2001 The Wilh Hennig Society.