Why did scientists remove salmon, trout, pike, and bonefish from the order Clupeiformes?

Historically, many fish species were grouped together in the order Clupeiformes (or Isopondyli) primarily because they possessed soft, rather than spiny, fin rays.1

However, in 1966, a major revision of bony fishes by P.H. Greenwood and his colleagues led to the removal of groups like salmons, trouts, and pikes from the order. Scientists determined that the superficial similarity of soft fin rays was overridden by more fundamental anatomical differences, which indicated a long history of phyletic separation.12

While the order Clupeiformes was restricted to groups such as herrings and anchovies, the salmon, trout, and pike species were reclassified into the order Salmoniformes (and related groups like Esociformes) based on distinct features found in both modern and fossil specimens. Other groups formerly included in the Clupeiformes, such as bonefishes, were similarly moved to different classifications as phylogenetic analyses clarified the evolutionary relationships among these teleosts.132