Scapanorynchus raphiodon

Scapanorhynchus raphiodon.

Turonian

Texas

Differentiating S. raphiodon and S.texanus is tricky, and in the cases of lateral teeth like this, it gets trickier, as S. texanus has variable laterals that share characteristics generally associated with S. raphiodon, such as weakly striated blades.

According to Becker et. al in the 2003 paper "Chondrichthyans from the Lower Ferron Sandstone Member of the Mancos Shale (Upper Cretaceous: Middle Turonian) of Emery and Carbon Counties, Utah, USA",  S.raphiodon can be distinguished from the later occurring S. texanus by its smaller size, less pronounced vertical striations, and its tendency to bear cusplets on anterior teeth. This barely helps eliminate options when no anterior teeth are present in your sample. So, concerning lateral teeth, one must rely on age.

Becker et. al continue their analysis of Scapanorhynchus with the following:

"According to Niedzwiedzki and Kalina (2003), S. raphiodon has a chronologic range of Cenomanian-Coniacian and may represent the predecessor of the lineage that later became S. texanus, which is known from the Campanian-Maastrichtian (Case and Schwimmer, 1988; Welton and Farish, 1993)"

They confirm this by citing several papers reporting S. raphiodon within the above chronologic range:

"Extensive literature exists on S. raphiodon, and the species is known from an associated dentition from the Niobrara Chalk of western Kansas (Hamm and Shimada, 2002). Turonian specimens of S. raphiodon in North America have been previously identified from the Codell Sandstone of Colorado (Edwards, 1976), Tres Hermanos Formation of New Mexico (Wolberg, 1985), Blue Hill Shale of eastern Nebraska (Kirk- land, 1989), upper Eagle Ford Group of Texas (Welton and Farish, 1993), Greenhorn Formation and Cariile Shale of Arizona, South Dakota and Wyoming (Williamson et al., 1993; Cicimurri, 2001, 2004), and the Semilla Sandstone Member of the Cariile Shale of central New Mexico (Johnson and Lucas, 2003). From the Straight Cliffs Formation of the Kaiparowits Plateau in south-central Utah, S. raphiodon is known from the Turonian Tibbet Canyon Member, and the genus is reported from the Coniacian-Santonian John Henry Member (Eaton et al., 1999)"

Thus, this confirms pretty strongly for me that despite the overlapping morphology, a middle turonian specimen such as this almost without a doubt represents S. raphiodon.