ICHTHYOTRINGIDAE

Miyata, Shinya, Isaji, Shinji, Kashiwagi, Kenji & Asai, Hidehiko, 2023, The first record of Lower Cretaceous otoliths from the Kimigahama Formation (Barremian) of the Choshi Group, Chiba Prefecture, Japan, Palaeontologia Electronica (a 20) 27 (1), pp. 1-23 : 11

Family ICHTHYOTRINGIDAE Jordan, 1905 Ichthyotringidae gen. et sp. indet.

( Figure 4G )

Reference material. CBM–PV 8208 ( Figure 4G ) and 6 other otoliths

Description. The otoliths are slender, thin, and approximately 2 mm length. The dorsal and ventral rims are abraded, and the posterior rims are slightly rounded. Striations are observed on the inner surface of the ventral area. The ostial region is tubular, and the anterior part of the rostrum is missing. The sulcus is closed at the posterior end, and the anterior opening is ostial. The cauda is medial, straight, and elongated toward the posterior part, but does not reach the posterior margin. The crista superior and crista inferior are present along the margin of the cauda. The dorsal depression is present above the crista superior.

Remarks. The specimens reported here are similar to those of Ichthyotringidae , including Thrax acutus Stringer et al., 2020, Ichthyotringa ? tavernei (Nolf and Stringer, 1996), I.? cuneata Schwarzhans et al., 2022, Apateodus crenellatus Schwarzhans and Stringer, 2020 , Apateodus corneti (Forir, 1887) , Apateodus ? assisi Schwarzhans et al., 2018b, and Apateodus sp. (Schwarzhans et al., 2018a, figures 7D-G) ( Table 3). The present specimens have several characteristics in common with Ichthyotringa ? tavernei; the otolith is slender; the cauda is straight, long, and elongated toward the posterior part; and there are striations on the ventral area. However, the present specimens have a dorsal depression and are small ( Ichthyotringa ? tavernei has no clear dorsal depression and reaches sizes greater than 3 mm). In I.? cuneata, the dorsal rim is clearly different from that of our specimen because it is square. Due to the wear and dissolution of this specimen, nothing more could be determined. Therefore, in the present study, these elongated otoliths were assigned to Ichthyotringidae , gen. et sp. indet.

Figures

FIGURE 4. Otoliths from the Kimigahama Formation (Barremian) in Chiba Prefecture, Japan. A-C: Elopiformes fam., gen. et sp. indet. A. CBM–PV 8206. A1) Dorsal view. A2) Line drawing of A1. A3) Inside view. A4) Line drawing of A3. B. CBM–PV 8326 B1) Dorsal view. B2) Inside view. C. CBM–PV 8327. C1) Dorsal view. C2) Inside view. D-F: Argentinidae gen. et sp. indet. D. CBM–PV 8207. D1) Dorsal view. D2) Line drawing of D1. D3) Inside view. D4) Line drawing of D3. E. CBM–PV 8328. E1) Dorsal view. E2) Inside view. F. CBM–PV 8329. F1) Dorsal view. F2) Inside view. G. Ichthyotringidae fam, gen. et sp. indet. G. CBM–PV 8208. G1) Dorsal view. G2) Line drawing of G1. G3) Inside view. G4) Line drawing of G3. Scale bar = 1 mm.