Rare?
I'm sure it isn't an everyday thing to find such fossils, but maybe it would be more common if paleontologists did more volunteer work, instead of just paid work studies. I've probably worked for free at least 1/4 of my life probing, walking, and digging for anything interesting, and I and my buddies have found bullets not made since 1886 embedded in bones and other artifacts, fossils with sharks teeth embedded in bone of who knows what, in fact it isn't sure what animal bit what other animal, but I am lucky enough to live in a region where one of the largest shallow seas was existent in the CT boundary. We've also found paleolithic arrow heads, knives, and spear points embedded in antlers and bone from the period - these are not tools or such fabrications but obviously from chaotic happenstance - my buddy is a collector and doesn't want to sell them, so he does not share the booty with archaeologists. I've been trying to get him to keep notes and at least record the GPS coordinates so scientists can follow up with studies some time in the future! Perhaps these boffins need to get out more?