Fossil range: Eocene
| Scientific classification
Knightia is an extinct genus of freshwater herring found in the Green River Formation of Wyoming, USA. They are well known across the world due to the extreme abundance of their fossils. Knightia existed 50-40 million years ago during the Eocene epoch. Hundreds of these fish can be found in a square yard of fossiliferous rock. Knightia typically grew around 3-5 inches (7.7-12.7 centimeters), and exceptionally large Knightia specimens have been recorded at 11 inches (28 centimeters) in length. During life they ate little arthopods, algae, the occasional baby fish, or anything they can fish into their tiny mouths. On the contrary, many Green River creatures ate them. Knightias were an important food source for larger fish, birds, snakes, turtles, and others. Suggested by mass mortality plates and modern behavior of herring, these fish lived in large shoals. Knightia is also Wyoming's state fossil.
Knightia belongs to the same taxonomic family as herring and sardines, and resembled the former closely enough that both Knightia alta and Knightia eocaena were originally described as species of true herring in the genus Clupea.
Rows of dorsal and ventral scutes ran from the back of the head to the medial fins. They had heavy scales, and small conical teeth. Their size varied by species: Knightia eocaena was the longest, growing up to 25 centimeters (10 inches), though most specimens are no larger than 15 centimeters. Knightia alta was shorter and relatively wider, with specimens averaging between 6 and 10 centimeters.
There are three known species in the Knightia genus.