Maybe you can explain how a trilobite without a hardened exoskeleton can
make Cruzina-type trace fossils, since these are made by the hardened
exoskeleton of the telopodites displacing sediment. It appears to me that
the case is somewhat different from that which you suggest. For example,
in Grand Canyon we find cruzina below the first trilobites in the Tapeats
Sandstone, but there are no body fossils until the overlying Bright Angel
Shale. However, this is upper Lower Cambrian to lower Middle Cambrian, and
nobody has suggested the trace fossils were made by other than the same
kind of bugs we find in the shale. To conclude that the trails that look
like the trails made by trilobites were made by trilobites without hard
parts because no skeletal remains were found in the same sediments is
wishful thinking on someone's part.
Art
http://biology.swau.edu