Ampheristus, KONIG, 1825

Stringer, Gary L. & Sloan, James Carson, 2023, First Cretaceous teleostean otolith assemblage (Arkadelphia Formation, upper Maastrichtian) from Arkansas, USA, early Gadiformes, and the Western Interior Seaway, PaleoBios 40 (1994), pp. 1-39 : 19

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) .

Figures

Figure 8. Otoliths from the Cretaceous Arkadelphia Formation. All specimens unless otherwise noted are inner views of right sagittae. Lapilli are macular views. Length in mm. A. Palaeogadus cf. P. weltoni Schwarzhans and Stringer (2020a), DMNH 2021-09- 23, 1.46 mm. B. Gadiformes indeterminate, DMNH 2021-09-24, 1.56 mm. C. Tippaha mythica Schwarzhans and Stringer (2020a), DMNH 2021-09-25, 3.85 mm. D. Eutawichthys maastrichtiensis Nolf and Stringer (1996), DMNH 2021-09-26, 3.93 mm. E. Eutawichthys zideki Nolf and Stringer (1996), DMNH 2021-09-27, 1.42 mm. F.Eutawichthys cf. E. stringeri Schwarzhans, Huddleston, and Takeuchi (2018b), DMNH 2021-09-28, 1.85 mm. G. Ampheristus cf. A. americanus Schwarzhans and Stringer (2020a), DMNH 2021-09-29, 1.58 mm. H. Protobythities brzobohatyi Schwarzhans (2010), DMNH 2021-09-30, 1.68 mm. I. Lapillus type 1, DMNH 2021-09-31, 2.98 mm.