What crucial detail is noted about the contemporary fish Ichthyodectes and Protosphyraena?

Answer

They were contemporary fish species swimming alongside Xiphactinus

The identification of Protosphyraena and Ichthyodectes within the stomach contents of Xiphactinus indicates that these were active, swimming victims, not scavenged remains. Because both species were contemporaries of the large predator, their presence confirms that Xiphactinus was actively hunting within its peer group of large, edible fish species inhabiting the same environment during that geological period.

What crucial detail is noted about the contemporary fish Ichthyodectes and Protosphyraena?
dietanimalfishXiphactinusPrehistoric