Reed, William JHughes, Barry D2014-08-182014-08-1820072007-03-22Reed and Hughes. Theoretical size distribution of fossil taxa. Theoretical Biology and Medical Modelling 2007, 4 :12http://www.tbiomed.com/content/4/1/12http://dx.doi.org/10.1186/1742-4682-4-12http://hdl.handle.net/1828/5572BioMed CentralBackground: 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. Model: 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. Conclusion: 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.enArticleDepartment of Mathematics and Statistics