Maenioceratidae Bogoslovsky, 1958

Bockwinkel, Jürgen & Korn, Dieter, 2024, Ammonoids of the Middle Devonian family Maenioceratidae in the Anti-Atlas of Morocco, European Journal of Taxonomy 921 (1), pp. 1-35 : 5-6

Family Maenioceratidae Bogoslovsky, 1958

Diagnosis

Family of the superfamily Pharciceratoidea without or with ventrolateral grooves; sutural formula (E 2 E 1 E 2) L U 2 U 1 I; wide to extremely wide external lobe.

Included genera

Maenioceras Schindewolf, 1933 ; Afromaenioceras Göddertz, 1987 ; Bensaidites Korn in Korn & Klug, 2002; Trimaenioceras gen. nov.

Remarks

The four genera of the family are very easily distinguished on the basis of the suture line, particularly the shape of the external lobe. This shows a small, rounded E 2 lobe in Maenioceras and Afromaenioceras , but deep and pointed in Trimaenioceras gen. nov. Maenioceras and Afromaenioceras differ in the shape of the E 2 lobe, which in the latter genus has a rectangular form.

The stratigraphic distribution of the four genera is only in part well-known. Bensaidites is probably the stratigraphically oldest representative of the family with “ B. koeneni ” defining the earliest Givetian ( Aboussalam & Becker 2011; Becker et al. 2018) in the Moroccan sections. Becker et al. (2004: pl. 1 fig. 22) illustrated a specimen from the basal part of the Oued Mzerreb section (bed -1a), which they named “ Bensaidites n. sp. ”. However, due to its suture line with a shallow, rounded E 2 lobe, this specimen belongs to Maenioceras .

It is clear that Maenioceras precedes Afromaenioceras ( Fig. 2 ), but the position of the material assigned here to the new genus Trimaenioceras gen. nov. has been conclusively determined. In Oued Mzerreb, Trimaenioceras klugi gen. et sp. nov. co-occurs with several Afromaenioceras species in the high part of the section (“ Afromaenioceras Beds ”).

Figures

Fig. 2. Givetian ammonoid “standard zones” (from Becker & House 2000) and zonations for the Anti-Atlas of Morocco (from Becker & House 2000; Aboussalam & Becker 2011; Becker et al. 2018). Interval with the species described here highlighted.