Perhaps the oldest remains of Protosphyraena in North America have come from the upper beds of the Dakota Sandstone (middle Cenomanian) in Russell County, Kansas (Everhart, 2005; p. 91).
The earliest fossil evidence of Protosphyraena in North America may be located in the upper layers of the Dakota Sandstone, which corresponds to the middle Cenomanian period, in Russell County, Kansas, as noted by Everhart (2005; p. 91).