Hi guys I'll try again....... You need to be looking around here if you're looking for an extinction around The Middle Cambrian Epoch : 513.0 to 501.0 million years ago. http://www.palaeos.com/Paleozoic/Cambrian/MidCam.html Ali -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.394 / Virus Database: 268.9.6/378 - Release Date: 6/28/2006