Progoniatites, Korn & Bockwinkel & Ebbighausen & Klug, 2003

Korn, Dieter, Bockwinkel, Jürgen, Ebbighausen, Volker & Klug, Christian, 2003, Palaeobiogeographic and evolutionary meaning of an early Late Tournaisian ammonoid fauna from the Tafilalt of Morocco, Acta Palaeontologica Polonica 48 (1), pp. 71-92 : 89

Progoniatites gen. nov.

Glyphioceras Hyatt 1884 ; Schindewolf 1926: 89.

Glyphioceras Hyatt 1884 ; Schindewolf 1939: 467.

Pericycloides gen. nov.; Follot 1953: 14. (nomen nudum).

Goniatites de Haan 1825 ; Pareyn and Conrad 1968:570. Glyphioceras Hyatt 1884 ; Conrad 1984: 100.

Zhifangoceras Sheng 1984 ; Kusina 2000: 22.

Derivation of name: After the close resemblance to the stratigraphically much younger genus Goniatites of the Viséan.

Type species: Progoniatites maghribensis sp. nov.

Diagnosis.— Goniatitidae with small globular conch. Aperture and whorl expansion rate low ( WER 1.60). Suture line with narrow, V−shaped external lobe and moderately high median saddle. Ventrolateral saddle asymmetrical and subacute. Large, V−shaped adventive lobe.

Other species included.— P. angustilobatum ( Schindewolf, 1926) from Thuringia, Germany, and P. karensis ( Kusina, 2000) from the Pay Khoy, Russia, both also early Late Tournaisian in age.

Comparisons.— Progoniatites gen. nov. has a conch shape and a suture line which closely resembles Goniatites de Haan, 1825 . The main difference is the shape of the ventrolateral saddle, which in Goniatites is truly acute, but only subacute with a narrowly rounded top in Progoniatites . Zhifangoceras Sheng, 1984 shows some similarities to Progoniatites , but its external lobe is much wider, the median saddle is higher (more than 0.60 of the external lobe depth, in contrast to 0.40 in Progoniatites ), and the ventrolateral saddle is far more rounded. In this respect, it resembles Pseudogirtyoceras Wagner−Gentis, 1982 , of which it may be a junior synonym. The conchs of Zhifangoceras are thickly discoidal, in contrast to the more globose conchs of Progoniatites .

Occurrence.— Progoniatites is known from the Tafilalt of Morocco, the Mouydir (Central Sahara) of Algeria ( Follot 1953; Conrad and Pareyn 1968), Thuringia ( Schindewolf 1926), and the South Urals ( Kusina 2000). All occurrences have probably an early Late Tournaisian age.