The fossil package is designed to be used by palaeoecologists and palaeobiogeographers (although will likely be of interest to others), providing to them a set of useful tools including species similarity indices, species estimators, minimum spanning tree/forest functions, and an assortment of other useful tools. The package consists of a set of analytical tools useful in analysing ecological and geographical data sets, and includes functions for estimating species richness (Chao 1 and 2, ACE, ICE, Jacknife), shared species/beta diversity, species area curves and geographic distances.
The package can be found on the CRAN website at http://cran.r-project.org/web/packages/fossil/
A more complete description of the individual functions can be found in my publication in Palaeontologia Electronica.
Vavrek, Matthew J. 2011. fossil: palaeoecological and palaeogeographical analysis tools. Palaeontologia Electronica, 14:1T. http://palaeo-electronica.org/2011_1/238/index.html