Cibolaites Cobban and Hook, 1983

KENNEDY, W. JAMES, COBBAN, WILLIAM A. & LANDMAN, NEIL H., 2001, A Revision Of The Turonian Members Of The Ammonite Subfamily Collignoniceratinae From The United States Western Interior And Gulf Coast, Bulletin of the American Museum of Natural History 2001 (267), pp. 1-148 : 29-34

Genus Cibolaites Cobban and Hook, 1983

TYPE SPECIES: Cibolaites molenaari Cobban and Hook, 1983: 16 , pl. 2, figs. 1–9; pl. 3, figs. 3–8; pl. 8, figs. 6–8; pl. 13, figs. 1– 5; pl. 14; text­figs. 13, 14; lower Turonian Mammites nodosoides Zone , west­central New Mexico .

DIAGNOSIS: A medium­size genus, largest known adults 120 mm in diameter; dimorphism not demonstrated. Coiling involute with small umbilicus, whorl section compressed to depressed, intercostal section with convergent sides and fastigiate venter, costal section markedly concave between tubercles. Strong conical umbilical bullae give rise to primary ribs singly or in pairs with shorter, intercalated ribs, all with ventrolateral and siphonal clavi on phragmocone. Umbilical bullae decline on the adult body chamber, which is flat­sided with crowded weak primary and intercalated

62. Figures are ×0.80.

ribs; ventrolateral and siphonal tubercles decline progressively and the venter flattens towards the adult aperture.

Suture relatively simple with broad, littledivided saddles and narrower, rectangular lobes.

DISCUSSION: Coarse tuberculation and presence of only a single row of ventrolateral tubercles distinguishes Cibolaites from all other genera currently referred to the Collig­ noniceratinae. Cibolaites superficially resembles Barroisiceras de Grossouvre, 1894 , and Subbarroisiceras Basse, 1946 , of the upper Turonian–Coniacian Barroisiceratinae . However, they differ in sutural characteristics, while both are more involute than Cibolaites , with smaller umbilici and crenulate keels; in Cibolaites there is no continuous keel and the siphonal clavi are separated by smooth interspaces.

14. Figures are ×0.80.

OCCURRENCE: Upper Cenomanian Neocardioceras juddii Zone in Devon, England and Aube, France; lower Turonian Mammites nodosoides Zone , immediately below first appearance of C. woollgari woollgari of the middle Turonian in west­central New Mexico; M. nodosoides Zone, N.W. Germany; also recorded from northern Spain (Kaplan, 1988) and from Tunisia (Chancellor et al., 1994).

Cibolaites molenaari Cobban and Hook, 1983

Figures 5–8

Collignoniceras sp. Wright and Kennedy, 1981:

107, pl. 8, fig. 17.

Cibolaites molenaari Cobban and Hook, 1983:

16, pl. 2, figs. 1–9; pl. 3, figs. 3–8; pl. 8, figs.

6–8; pl. 13, figs. 1–5; pl. 14; text­figs. 13, 14.

Cibolaites molenaari Cobban and Hook. Kennedy

et al., 1986: 209, text­fig. 5i, j, k, l.

Figures

Fig. 5. Cibolaites molenaari Cobban and Hook, 1983. Holotype, USNM 328766, a gracile individual from locality 44. All figures are ×1.

Fig. 6. Cibolaites molenaari Cobban and Hook, 1983. A–C. Paratype USNM 328761, a gracile