So far our essential collectibles have been invertebrate fossils, remains of animals without backbones such as ammonites and trilobites. Vertebrate fossils are much rarer, and consequently more expensive, the pocket money-priced ones tending to be things like sharks’ teeth or small fragments of reptile bone. Certainly, even a small fully articulated dinosaur skeleton is the sort of thing that’ll set you back many thousands of pounds! But exceptions to this rule can be found among the Green River fishes, well preserved fossils with all their bones in place thanks to the rapid burial and fossilisation of the original animals.
Of course there are rare species like stingrays that command high prices, but individual Knightia and Diplomystus can be had for a few tens of pounds, while the less common Priscacara goes for a little bit more. Either way, these are fish most collectors end up with sooner or later, whether bought for themselves or received as gifts.