Gonorynchiformes represent a group of ray-finned fish more commonly known as Milkfish. Evolving during the Early Cretaceous, these streamlined, toothless fish feed generally on marine algae.

There is currently only one named species of Gonorynchiformes found within the London Clay, that of Halecopsis insignis.

This artistic reconstruction shows a shoal of shimmering Halecopsis insignis (milkfish) feeding on algae on the bottom of floating driftwood in the sub-tropical Eocene seas.