Earth is a dynamic planet. If anything has been constant throughout Earth history, it is its relentless state of flux -- from the ceaseless motion of tectonic plates to the ever-changing climate that eventually led to the birth of life itself to the steady bombardment of asteroids, some of which led to large-scale extinction events. PaleoEarth brings together a number of disparate data sets and provides a unique window into Earth's dynamic history. Key features include:

* Shows the motion of continental plates, subduction zones (where oceanic crust sinks into the Earth's mantle) and mid-ocean ridges (where new oceanic crust is created) over the last 50 million years.

* Shows sites of major asteroid impacts, tracing them from their original location at the time of impact to their current location, having been transported by the motion of tectonic plates.

* Shows how Earth's temperature and atmospheric co2 concentration compare to present-day values, over the last 50 million years.

* Traces the borders of a given country back in time, over the last 50 million years.

The paid version, PaleoEarth, goes back to 400 million years.