Arius subtilis, Schwarzhans and Bratishko, 2011

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 : 12

ARIUS? SUBTILIS SCHWARZHANS AND BRATISHKO, 2011

FIG. 6C

Material— one well preserved specimen, DMNH 2021-09-11.

Description and Remarks— Arius? subtilis is represented by the utricular otolith or lapillus rather than the sagitta. The lapillus is oval in outline (sensu Smale et al. 1995) and has characteristically smooth margins except for one diagnostic projection. It is typically plano-convex and usually fairly thin. The flat side often has radial growth lines visible, especially in eroded specimens. In some specimens, a very lightly impressed sulcal area may be visible on the convex side. Arius? subtilis was first identified in the Paleocene of the Ukraine by Schwar- zhans and Bratishko (2011) and is fairly common in the early Paleocene of Europe ( Schwarzhans 2012). It is also known from the Clayton Formation (early Paleocene) of the USA ( Schwarzhans and Stringer 2020a). However, its range was extended to the Late Cretaceous when it was reported from the Ripley and Owl Creek formations of Mississippi (Stringer et al. 2020), where it was abundant (125 specimens from the two formations). It also occurs in the Coon Creek Formation in Tennessee (as Ariidae indeterminate in Stringer 2016b) and in the Kemp Clay (upper Maastrichtian) of northeast Texas, where it was very abundant with 195 specimens ( Schwarzhans and Stringer 2020a). The rarity of Arius? subtilis in the stratigraphically equivalent Arkadelphia Formation is enigmatic.

Figures

Figure 6. Otoliths from the Cretaceous Arkadelphia Formation. All specimens unless otherwise noted are inner views of right sagittae. Length in mm. A. Kokenichthys navis Schwarzhans and Stringer (2020b), DMNH 2021-09-9, 4.10 mm. B. Clupeiform? indeterminate DMNH 2021-09-10, 1.42 mm. C. Arius subtilis Schwarzhans and Bratishko (2011), DMNH 2021-09-11, 4.61 mm. D. Vorhisia vulpes Frizzell (1965b), DMNH 2021-09-13, 2.49 mm. E. Vorhisia vulpes Frizzell (1965b), DMNH 2021-09-14, 3.06 mm. F. Vorhisia vulpes Frizzell (1965b), DMNH 2021-09-15, 3.99 mm. G. Vorhisia vulpes Frizzell (1965b), DMNH 2021-09-16, 7.98 mm. H. Vorhisia vulpes Frizzell (1965b), DMNH 2021-09-12, 19.36 mm.