|MadSci Network: Evolution|
Because there have been many discoveries in the depths of the World's oceans I cannot completely rule out the possibility that some species of trilobite (possibly highly modified for deep sea life) could still live there. Some fossil species did live in the deep sea, however, most trilobites were probably relatively shallow water forms. To make a long answer short- probably not, but we don't know for sure! I recommend: Subphylum Trilobita: http://www.earthlife.net/inverts/trilobita.html This site has some book references that you also might find interesting!
Try the links in the MadSci Library for more information on Evolution.