How does the caudal skeleton of paracanthopterygian fishes differ from that of many other fishes?

The caudal skeleton of paracanthopterygian fishes is distinguished by specific structural characteristics that differ from those of many other teleosts. In these fishes, the second ural centrum is fused with the upper hypural bone. Additionally, the caudal skeleton of the superorder Paracanthopterygii typically features two or fewer epurals and a full neural spine on the second preural centrum.1

These features are part of the broader anatomical profile of the group, which generally represents a trend toward the loss of primitive acanthopterygian characters.1