Description
Knightia are small freshwater fish often described as “herring-like' that lived in North America during the Eocene period. They were a schooling fish and are often preserved in their shoals with some specimens even preserved on top of each other. For this reason the Knightia specimens are one of the most commonly traded fossils on the market.
‘The majority of Knightia specimens are quite small, but some large specimens around twenty-five centimetres long are known. Although Knightia may seem a small and unimportant fish, their sheer numbers strongly suggest that they would have formed an important part of their ecosystem’s biomass, being an abundant food supply for predators.
Source: http://www.prehistoric-wildlife.com/species/k/knightia.html