The specimen shown in the collage below was found by Don Campbell, who also did the preparatory work on it. It is a single dalmanitid pygidium that appears to have been bitten in several places over a large area. The unique, deeply chevroned gouge marks bordered locally in places by points suggest to me that the predator was a cephalopod. The smooth edge of the wound, however, suggests healing occurred, which means the animal survived the attack.
In addition to the specimen above, Bill Rushlau found the one below. Interestingly, it shows injury in almost the same location as the specimen above, though the pattern is distinctly different. Notice also the injury damage on the left posterior pleural field. Is it possible this occurred when the bite on the right was in progress, and the predator shook its victim? Again, as above, the smooth edges of the bite marks suggest this animal survived the attack and was allowed to heal to some extent. Closer views of the injuries on each side are shown below the larger, plan view of the pygidium.
More information is available in the following publications and references cited therein:
L.E. 1993. Trilobite malformations and the fossil record of behavioral asymmetry. Journal
of Paleontology, 67(2): 217-229. Babcock,
L.E. & Robinson, R.A. 1989. Preferences of Palaeozoic predators. Nature, 337:
697-698. K.J. McNamara and M.E. Tuura 2011, Evidence for Segment Polarity During Regeneration in the Devonian Asteropygine Trilobite Greenops widderensis, Journal of Paleontology, 85(1): 106-10.
Vannier, J., Iten, H.V. & Zhao, Y.L. 2004. Direct evidence of
predation on trilobites in the Cambrian. Proceedings of the Royal Society
of London, 271: