Amaltheus cf. stokesi (J. Sowerby, 1818)

Seyed-Emami, Kazem, Fürsich, Franz T., Wilmsen, Markus, Majidifard, Mahmoud R. & Shekarifard, Ali, 2008, Lower and Middle Jurassic ammonoids of the Shemshak Group in Alborz, Iran and their palaeobiogeographical and biostratigraphical importance, Acta Palaeontologica Polonica 53 (2), pp. 237-260 : 243-244

Amaltheus cf. stokesi (J. Sowerby, 1818)

Fig. 4B.

1818 cf. Ammonites Stokesi ; J. Sowerby 1818: 205, pl. 190.

1977 Amaltheus stokesi (Sowerby) ; Nabavi and Seyed−Emami 1977: 81, fig. 9 (5, 6 only).

1998 cf. Amaltheus stokesi (Sowerby, 1818) ; Géczy and Meister 1998: 102, pl. 6: 10 (with synonymy).

2003 Amaltheus stokesi (Sowerby, 1818) ; Hosseinzadeh 2003: 61, pl. 1: 17, 18.

Material.—Several poorly preserved inner whorls from Shahmirzad (050514−6).

Description and discussion.—Among the small and poorly preserved amaltheids from Shahmirzad there are several specimens which may be assigned to A. stokesi . The figured specimen (050514−6/6) is a relatively coarsely ribbed Amaltheus . The ribs bifurcate near the venter and cross it as chevrons. The passage from the flank to the venter is gradual, and the keel is not as prominent as that of A. margaritatus . Juvenile specimens of A. stokesi and A. margaritatus cannot be distinguished from each other with certainty, which has been already mentioned by Howarth (1958: 5).

Stratigraphic and geographic range.—Shahmirzad, level II. A. stokesi is widely distributed in the boreal regions of northwest Europe, northwest America, Siberia and Caucasus, occurring in the Amaltheus stokesi Subzone of the Amaltheus margaritatus Zone, Late Pliensbachian ( Smith and Tipper 1996: 51) .