Orthosphinctes (O.) tiziani (Oppel, 1863)

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 : 538

Orthosphinctes (O.) tiziani (Oppel, 1863) ( Fig. 13A )

Ammonites tiziani Oppel, 1863: 246 .

Perisphinctes tiziani – Choffat 1893: 32, pl. 5, fig. 8.

Perisphinctes tiziani var. occidentalis Choffat, 1893: 32 , pl. 5, figs 5-7.

? Perisphinctes aff. tiziani – Choffat 1893: 33, pl. 7, fig. 1.

Pars Perisphinctes tiziani – Wegele 1929: 44, pl. 1, fig. 4a, b, non 5.? Perisphinctes (Orthosphinctes) tiziani – Geyer 1961: 19, pl. 1, fig. 1, pl. 2, fig. 1, pl. 6, fig. 3. Orthosphinctes (Orthosphinctes) tiziani – Matyja & Wi- erzbowski 1997: pl. 6, fig. 1. MATERIAL EXAMINED. — MI4N 8 “top”/11. STRATIGRAPHIC DISTRIBUTION. — The specimen has been collected in bed 8d of section Monte Inici East, assigned with doubt to the Hauffianum Subzone of the Late Oxfordian Bimammatum Zone. Olóriz et al. (1998, 1999) have reported this species from both the Bimam- matum and Planula zones. DESCRIPTION Evolute, serpenticone shell. The whorl section is subcircular, characterized by rounded flanks and a large, rounded venter. Flanks slightly flatten in the last half of the last whorl. The umbilical mar- gin is round, the umbilical wall is low and poorly developed. The ornamentation is made of radial, mostly biplicate ribs up to the first third of the last whorl, then, after a deep constriction ribbing be- comes slightly prorsiradiate and some intercalatory ribs appear. The point of branching is very high, approximately in the upper fourth of the flank. Three constrictions are visible on the last whorl; one of them is deeper, oblique to the ribbing and adorally bounded by a swollen rib. The peristome is not preserved and the suture line is not visible. Measurements: see Table 23.

DISCUSSION

This specimen shows morphological affinities with the lectotype of O. (O.) tiziani selected by Wegele (1929: pl. 1, fig. 4), from which it differs because of the lower rib density.

Figures

FIG. 13. — A, Orthosphinctes (Orthosphinctes) tiziani (Oppel, 1863), specimen MI4N 8 “top”/11 from bed 8d of section Monte Inici East; B, Orthosphinctes (Orthosphinctes) aff. fontannesi (Choffat, 1893), specimen MI4N 8 “top”/3, from bed 8d of section Monte Inici East; C, Orthosphinctes (Ardescia) betica Caracuel, Olóriz & Rodriguez-Tovar, 1999, specimen MI4N top10/1 from bed 10 of section Monte Inici East. All figures natural size. Arrows indicate the beginning of the body chamber.