397 Million Year-Old Tetrapod Footprints Found

[Giant Blue Anteater]

Footprints of a possible early tetrapod dating back 397 million years ago have been found in southeast Poland.

Articles relating to this find:
http://newsvote.bbc.co.uk/2/hi/science/nature/8443879.stm
http://www.guardian.co.uk/commentisfree/2010/jan/06/fossil-footprints-land-animal

 

[Doc.]

yeah heard that on the radio yesterday evening

 

[Shapeshifter]

how do they know how old it is?

edit: mh okay. they dated the rock.