The burst of life in the Ordivician is thought to have been due to a meteorite storm around 470 million years ago. Many L Chondrites have been discovered in sedimentation relating to this age but a newly discovered type of meteorite has now been discovered in Sweden. The findings have been published in Earth and Planetary Science Letters but a New Scientist article appears http://www.newscientist.com/article/dn25817-swedish-space-rock-may-be-piece-of-early-life-puzzle.html?cmpid=RSS%7CNSNS%7C2012-GLOBAL%7Conline-news#.U7PyTZR3KpX.
The Journal can be found at http://www.sciencedirect.com/science/article/pii/S0012821X14003367. I have been able to download it but this was via my Open University Library access so not sure if others will be able to view.
Andy