What is "opsithrissops"

Opsithrissops ( Ancient Greek: "Aspect Fish Face") is an extinct genus of prehistoric bony fish that lived during the Thanetian stage of the Paleocene epoch. It is a small nektonic opportunistic carnivore in the family Osteoglossiformes which includes other bony-tongues such as the extant species of Arowana and Arapaima. It hunted small invertebrates and fish similarly to today's trout and became a Paleogene keystone species in many habitats before its disappearance from the fossil record.