AMPHERISTUS CF. A. AMERICANUS SCHWARZHANS AND STRINGER, 2020a

FIG. 8G

Material— six specimens, specimen figured, DMNH 2021-09- 29.

Description and Remarks— The sagitta of Ampheristus cf. A. americanus is basically oval (sensu Smale et al. 1995) with a long, nearly straight, smooth dorsal margin, while the ventral margin is regularly curved, deepest anterior of its middle, and relatively shallow. The inner face is convex horizontally with a long, slightly s-shaped sulcus that is medially located. The sulcus almost reaches the anterior margin but ends well before the posterior margin. Ampheristus americanus was first named by Schwarzhans and Stringer (2020a) based on 143 specimens from the Kemp Clay (Maastrichtian) of Texas and the Clayton Formation (Danian) of Arkansas. According to Schwarzhans (1981) the fossil genus Ampheristus is considered to be closely related to the extant Hoplobrotula Gill (1863) .