Life history on Earth

Instructions

If you don't see anything above, please install
Java 1.4)

The database open for various ways to view the data fororrigination and extinction of life on earth. First one select the sub-section of data one wants to view by selecting a starting genera number N, and how many genera one wants to view in total (dN). The genera are numbered consecutively as in Sepkoski's database where more related genera tends to be closer to each other.

In plots type=0,1,3,4 and the x-axis rank the data after the genera number in the Sepkoski Database. The different plot types are:

plot type=0: show total life time of each genera.

plot type=1: show time period where each genera existed.

plot type=2: show duration matrix where we at genera give rice to a count at position (x,y) where x is origination time and y extinction time. Larger dots and lighter color indicate that many genera shared same fate.

plot type=3: show rice and fall of orders in terms of how many genera they consisted of.

plot type=4: like type=3, but slightly differently plotted.

plot type=5: Total number of genera, color coded according to which order they belong to.

plot type=6: like 5 but with uniform color.

Color code opens for various color schemes, where we in particular recommend code=1. In any case color is graded according to origination time (except in type=2). Further with Alternating color=1, then each second taxonomic Order is colored according a blue grading. Thereby one can separate orders visually.

Philosophy

This applet display a large part of the known fossil record. The underlying data is from Sepkoski's extensive library studies, collected in his database of origination and extinction of about 36000 genera.

A genera is a group a species, like we humans for example are part of the genera consisting of neandertals, cro-magnon etc. The database of Sepkoski mainly consist of marine animals. The applet deal with the 31363 genera in the database which are not existing now. The data are grouped in Orders, a taxonomic unit which often only contain a few genera, but sometimes consists of more than 1000 genera. In general closely related genera tends to be closer along the genera number.

The various ways to present the data emphasize correlation between extinctions across different taxonomic groups, it emphasize certain large scale extinction events, and also one could see that closely related genera often have similar lifetimes, even when they live at widely different times. The data treatment are systematized in our publication by Bornholdt, Sneppen and Westphal below.

Litterature:

J.J.Jr. Sepkoski and A.I. Miller (1988) Paleobiology 14, 364-369.

J.J.Jr, Sepkoski (2002) A Compendium of fossil marine animal genera. Edited by D. Jablonski and M. Foote., M. buletin of American Paleontology 363, 563 pages.

S. Bornholdt, K. Sneppen, H. Westphal. Longevity of orders is related to the longevity of their constituent genera rather than genus richness (2006). q-bio.PE/0608033