Tornquistes (Tornquistes) cf. romani (Douvillé, 1912)

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 : 516-517

Tornquistes (Tornquistes) cf. romani (Douvillé, 1912) ( Fig. 4D )

MATERIAL EXAMINED. — MI3 9/7.

STRATIGRAPHIC DISTRIBUTION. — Bed 9 of section Castello Inici, which has been assigned to the Middle Oxfordian Plicatilis Zone.

DESCRIPTION

Incomplete specimen corresponding to the body chamber of an individual that reached a diameter of about 60 mm. The shell is globular and rather involute. The whorl section is ovate, with convex flanks converging towards the narrow venter. The umbilical edge is rounded and no umbilical wall is visible. Bundles of two strong, radiate ribs spring from radial umbilical bullae. Single ribs are intercalated between the bundles.

DISCUSSION

The poor preservation of our specimen prevents its precise identification. The morphologically closer species is Tornquistes (T.) romani . It is impossible to state if the specimen studied corresponds to an adult or to an immature individual but its rib density and, apparently, its umbilical width can be compared to immature specimens of similar diameter described by Thierry & Charpy (1982). The preservation does not allow observing whether the umbilical wall is really not developed or if it is simply not observable. Tornquistes (T.) multicostatum Thierry & Charpy, 1982 and T. (T.) helvetiae (Tornquist, 1896) have more evolute shells.

Figures

FIG. 4. — A, Calliphylloceras benacense (Catullo,1847),specimen MI4N 8b/2 from bed 8b of section Monte Inici East;B, Sowerbyceras tortisulcatum (d’Orbigny,1841),specimen MI4N 6c/1 from bed 6c of section Monte Inici East;C, Holcophylloceras polyolcum (Benecke, 1866), specimen MI4W 8b/c/1 from bed 8c of section Monte Inici East; D, Tornquistes (T.) cf. romani (Douvillé, 1912), specimen MI3 9/7 from bed 9 of section Castello Inici; E, Streblites frotho (Oppel, 1863), specimen MI4N 8b/1 from bed 8b of section Monte Inici East. All figures natural size. Arrows indicate the beginning of the body chamber.