What is "tripteroceratidae"

The Tripteroceratidae is a family of depressed, straight to slightly curved nautiloid cephalopods from the middle and upper Ordovician with generally flattened venters and empty siphuncles with straight to inflated sedments included in the Oncocerida (Sweet, 1964).

The Tripteroceratidae appeared almost simultaneously with the Oncoceratidae and Valcouroceratidae early in the Middle Ordovician, and are most likely derived from the Graciloceratidae.