Vetulicolia are primitive deuterostomes from the very early Cambrian of China. The have a body with gills (or at least slits in the vicinity of the pharynx) and a segmented tail. The Vetulicolia are believed to be very similar to the ancestors of all deuterostomes.
Links:
New phylum on the block (http://www.geolsoc.org.uk/template.cfm?name=OFNANP)