Why did the discovery of a living coelacanth not greatly change fish classification?

The discovery of a living coelacanth in 1938 did not fundamentally alter fish classification because these fishes had already exhibited exceptional evolutionary stability for hundreds of millions of years.1

By the time the first living specimen was identified, scientists had already established a clear understanding of the group's anatomy and evolutionary history through an extensive fossil record dating back to the Devonian Period. Because the ancient fossil forms were already highly specialized and morphologically similar to the modern Latimeria, the living fish served primarily to confirm existing scientific reconstructions rather than to contradict them.21

While the discovery was a significant biological event, it functioned as a "living fossil" validation of established taxonomic frameworks within the subclass Crossopterygii, rather than a catalyst for a major reclassification of bony fishes.21