Eubaculites Spath, 1926

KENNEDY, W. J., LANDMAN, N. H., COBBAN, W. A. & JOHNSON, R. O., 2000, Additions to the Ammonite Fauna of the Upper Cretaceous Navesink Formation of New Jersey, American Museum Novitates 3306, pp. 1-31 : 16-18

Genus Eubaculites Spath, 1926

TYPE SPECIES: Baculites vagina var. Ootacodensis Stoliczka, 1866 (p. 199, pl. 90, figs. 14,?15), by original designation, from

the Maastrichtian of Ootacod, south India, = Baculites labyrinthicus Morton, 1834, p. 44 , pl. 13, fig. 10.

Eubaculites cf. E. labyrinthicus (Morton, 1834) Figure 4P, Q

compare:

Baculites labyrinthicus Morton, 1834: 44 , pl. 13, fig. 10.

Baculites labyrinthicus Morton, Gabb, 1861a: 394 , pl. 3, fig. 1.

Baculites labyrinthicus Morton, Gabb, 1861b: 77 .

DESCRIPTION: USNM 445379 (fig. 4P, Q) is a plaster cast of a septate fragment 38.5 mm long, with a whorl height of 32.0 mm and a whorl breadth of 18.9 mm (ratio of whorl breadth to whorl height is 0.59). The dorsum is broad and flat with a narrowly rounded dorsolateral margin. The dorsal flanks are flattened and divergent; the mid­flank region, which is the point of greatest whorl breadth, is broadly rounded; the outer flanks are flattened and converge to a narrowly rounded venter. Traces of a transverse rib are preserved on the dorsal half of the flanks at the larger end of the specimen. The sutures are intricately subdivided.

DISCUSSION: The fastigiate rather than tabulate venter suggests that this is a specimen of Eubaculites nearest to E. labyrinthicus (Morton, 1834) (p. 44, pl. 13, fig. 10), originally described from the Prairie Bluff Chalk of Alabama. Eubaculites carinatus (Morton, 1834) (p. 44, pl. 13, fig. 1), the prior name of the widely recorded E. lyelli (d’Orbigny, 1847) (see Kennedy, 1987: 195, pl. 27, figs. 5–8, pl. 32, figs. 13, 14, with synonymy) is easily distinguished by its crescentic flank ribs and tabulate venter. Eubaculites simplex (Kossmat, 1895) (p. 156, pl. 19[5], figs. 13a, b, non pl. 19[5], figs. 14a, b) has a tabulate venter and is smooth. Eubaculites vagina (Forbes, 1846) (see figures in Klinger, 1976) has a tabulate venter and bituberculate flanks.

OCCURRENCE: This specimen was collected from the basal part of the Navesink Formation in a tributary on the west side of Crosswicks Creek south of Allentown , Monmouth County, New Jersey. The specimen is associated with a large collection of Baculites ovatus .