Spectral ordering and biochronology of European fossil mammals

—Spectral algorithms have been shown to work well in a wide range of situations that involve the task of ordering. When applied to the localities of a set of European Neogene land mammal taxa, spectral ordering relies almost entirely on the most common genera, depends on connectivity more than on length of taxon lists, and is robust to noise from rarer and less connected taxa. The spectral coefficients for localities are highly correlated with known geochronological ages. Although elementary compared with more sophisticated biochronological tools, spectral ordering allows a fast and standardized way to generate biochronological ordering of localities when other information than faunal lists is lacking. Compared with the conventional mammal Neogene (MN) units, spectral ordering of localities appears to lack distinct temporal boundaries in taxon content and render a much lower count of Lazarus events. If, as seems to be the case, biochronology depends mainly on the most common taxa and if evolutionary change is also most clearly reflected in them, then the main evolutionary patterns should be detectable at a modest level of sampling. Mikael Fortelius.* Department of Geology and Institute of Biotechnology, Post Office Box 64, FIN-00014 University of Helsinki, Finland. E-mail: [email protected] Aristides Gionis and Heikki Mannila. HIIT Basic Research Unit, Department of Computer Science, Post Office Box 68, FIN-00014 University of Helsinki, Finland Jukka Jernvall. Developmental Biology Program, Institute of Biotechnology, Post Office Box 56, FIN-00014 University of Helsinki, Helsinki, Finland and Department of Ecology and Systematics, Post Office Box 65, FIN-00014 University of Helsinki, Finland *Corresponding author Accepted: 7 September 2005