Nebrodites cf. hospes (Neumayr, 1873)

Cecca, Fabrizio & Savary, Bérengère, 2007, Palaeontological study of Middle Oxfordian- Early Kimmeridgian (Late Jurassic) ammonites from the Rosso Ammonitico of Monte Inici (north-western Sicily, Italy), Geodiversitas 29 (4), pp. 507-548 : 528

Nebrodites cf. hospes (Neumayr, 1873) ( Fig. 8D )

MATERIAL EXAMINED. — MI4W 10top/3, MI4W 10top/4.

STRATIGRAPHIC DISTRIBUTION. — Bed 10 of section Monte Inici East, which has been assigned to the Early Kimmeridgian Platynota Zone.

DESCRIPTION

Evolute shell. Only the lower third of the flank of the final part of the last whorl is preserved in specimen MI4W 10top/3 on which the description is based. The whorl section is subelliptical, with gently rounded flanks and venter. The ribbing is rectiradiate to slightly prorsiradiate with an almost regular alternance of simple and bifurcate ribs. These branch at the upper third of the flank and become slightly projected on the venter, where they stop along a smoothed band. The incomplete preservation prevents the observation of the real number of constrictions: three constrictions per whorl have been observed on the preserved portions. The body chamber is not preserved, except for the final part of the last whorl. A small fragment (MI4W 10 top/4) of the body chamber of an individual, which probably reached the diameter of 90 mm, shows the same ornamental characters. Sculpture did probably not undergo significant ontogenetic changes. Measurements: see Table 14.

DISCUSSION

The form described above bear morphologic affinities with the specimen figured by Benzaggagh & Atrops (1997: pl. 1, fig. 6) as N. hospes suteri Geyssant, 1966 , which is a morphotype originally considered as a subspecies that groups evolute and densely ribbed specimens of N. hospes . Sarti (1993) has questioned the use of this subspecies which he includes within N. hospes sensu stricto. The preservation of our specimens is too incomplete to reach a reliable determination. Nevertheless, their finding in association with Orthosphinctes (Ardescia) beticus Caracuel, Olóriz & Rodriguez-Tovar, 1999 further confirms the occurrence of typical Nebrodites in the Platynota Zone.

Family ASPIDOCERATIDAE Zittel, 1895

Figures

FIG. 8. — Nebrodites aff. contortus (Neumayr, 1871), specimen MI4N 8d/2 of bed 8d top of section Monte Inici East; A, lateral view; B, ventral view; C, Nebrodites passendorferiiforme Caracuel, Olóriz & Rodriguez-Tovar, 1999, specimen MI4W 10top/2 from bed 10 of section Monte Inici East; D, Nebrodites cf. hospes (Neumayr, 1873), specimen MI4W 10top/3 from bed 10 of section Monte Inici East; E,?“Passendorferia” aff. teresiformis Brochwicz-Lewinski, 1973, specimen MI4N 8 “top”/5 from bed 8d of section Monte Inici East. All figures natural size. Arrows indicate the beginning of the body chamber.