Argument #1: Transitional Fossils

[Anomalocaris]

Actually, there are many sites around the world that offers large arrays of Cambrian fossils. But You are unlikely to find the ancestress of trilobites in Cambrian fossils because at the beginning of Cambrian, trilobites are already clearly distinguished from their arthropod relatives and have the full array of distinguishing trilobite features. This indicates the common ancestor of all Arthropods considerably predate Cambrian, and trilobite lineage, as well as other arthropod lineages, already had a long independent heritage at the start of Cambrian.

The Cambrian explosion isn't so much an sudden explosion of life without known ancestors. It is actually the sudden explosion of fossils of calcium based, mineralized shells. It is thought that prior to Cambrian, ocean water chemistry did not support the formation of hard, mineralized calcite shells. Ancestors of those trilobites that left the earliest fossils of trilobite shells were still trilobites, just trilobites with shells that didn't contain calcite and so is much harder to preserve.

This doesn't mean pre-Cambrian trilobites can't fossilize, just fossilization of trilobites without mineralized shells are much more rare, those that fossilize are more likely to be in poorer state of preservation, and what is preserved would be more difficult to recognize as trilobites.

I maybe mistaken but I was under the impression that most of what we know of the cambrian comes from the burgess shale in Canada and a site in china, I could be wrong. Eitherway you have a hard enough time finding sedimentary rock from the ediacarian let alone fossils from that, which as you state, likely didn't have mineralized shells.

Burgess was the first big Precambrian find, around the turn of last century. A big find was made in china in the late 1970s and early 1980s, but these were followed shortly afterwards by many other Cambrian sites around the world. We now have a pretty good chronological column of fossils and fauna covering the whole if Cambrian, not just one or two slices in time in Cambrian.

You can now see lineages evolving within Cambrian, each fossil being a transition for something else that comes later.

As usual, more data and better understand will turn anything into a nightmare for biblical morons. Cambrian is certainly not excluded.