Photo: National Park Service, Fossil Butte National Monument
- Order
- Osteoglossiformes
- Family
- Osteoglossidae
- Size
- Up to about 30 inches
A predatory bony-tongue fish that schooled young and hunted alone as an adult.
Living members of the Osteoglossidae family include 10 species that live exclusively in tropical freshwaters in South America, Africa, Asia, and Australia. Modern Osteoglossidae are mouth-brooders (parents hold eggs and hatchlings in their mouths).
Phareodus adult fossils are usually found alone, but juveniles are known from mass mortalities. This indicates that Phareodus schooled as a juvenile and became solitary as an adult. Fossils are often preserved with smaller fish in their jaws and stomach; this as well as their large, sharp teeth indicates they were predators.
Their rearward oriented fins on back and underside were an adaptation for speed. The maximum known size of P. encaustus is 30 inches.
Species text: National Park Service, Fossil Butte National Monument — Fossil Fish Species.