title: Theoretical size distribution of fossil taxa: analysis of a null model.
abstract: BACKGROUND
  This article deals with the theoretical size distribution (of number of sub-taxa) of a fossil taxon arising from a simple null model of macroevolution.
  
  
  METHODS
  New species arise through speciations occurring independently and at random at a fixed probability rate, while extinctions either occur independently and at random (background extinctions) or cataclysmically. In addition new genera are assumed to arise through speciations of a very radical nature, again assumed to occur independently and at random at a fixed probability rate.
  
  
  CONCLUSIONS
  The size distributions of the pioneering genus (following a cataclysm) and of derived genera are determined. Also the distribution of the number of genera is considered along with a comparison of the probability of a monospecific genus with that of a monogeneric family.
authors: Department of Mathematics and Statistics, University of Victoria, Victoria, British Columbia V8W 3P4, Canada. reed@math.uvic.ca
authors: William J
authors: WJ
authors: Reed
authors: Barry D
authors: BD
authors: Hughes
mesh_terms: D000818:Animals; D005075:Biological Evolution; D049628:Body Size; D002965:Classification; D005580:Fossils; D008954:Models, Biological