The four analyses

1. Phylogenetic. Genus counts aggregated up the tree to high-level nodes.
2. Timeline. Genera counted by the earliest geological age in which they occurred, and aggregated up to epoch and period.
3. Geographical. Genera counted by country of discovery, and aggregated up to continent.
4. Historical. Genera counted by year of naming, and aggregated up to decade.

1. Phylogenetic. Genus counts aggregated up the tree to high-level nodes.