Jeletzkytes Riccardi, 1983

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 : 20-26

Genus Jeletzkytes Riccardi, 1983

TYPE SPECIES: Scaphites nodosus Owen, 1852 (p. 581, pl. 8, fig. 4, by original designation) .

Jeletzkytes cf. J. nodosus (Owen, 1852)

Figures 9J–P , 10 , 11 , 12C–F

compare:

Scaphites (Ammonites) nodosus (N.S.) Owen, 1852: 581, pl. 8, fig. 4.

Jeletzkytes cf. J. nodosus (Owen, 1852) , Kennedy et al., 1995: pl. 6, fig. 3.

DESCRIPTION: MAPS A2020a1 (fig. 10) is a large, nearly complete macroconch body chamber 116 mm long. It has a pronounced umbilical bulge. There are 11 umbilicolateral bullae and 7 much larger ventrolateral clavi. The ribs are strong and widely spaced and cross the venter with an adoral projection.

MAPS A2020a2 (fig. 11) is a large, well­preserved microconch, 89.2 mm in maximum length; the adoral portion of the hook is missing. The phragmocone is robust with a ratio of whorl breadth to whorl height of 1.33 at the ultimate septum. There is a deep umbilicus with a steep umbilical wall and a sharply rounded umbilical shoulder. The whorl section of the phragmocone is subquadrate with broadly rounded flanks, sharply rounded ventrolateral shoulders, and a broadly rounded venter. Strong primary ribs arise on the umbilical wall and are rectiradiate on the flanks. They bear strong umbilicolateral bullae. Single ribs link these bullae to equally prominent ventrolateral tubercles. Two or three ribs loop between ventrolateral tubercles on either side of the venter. One or two equally strong nontuberculate ribs intercalate between these groups. All ribs cross the venter with a broad convexity.

The body chamber is robust with a ratio of whorl breadth to whorl height of 1.25 at mid­shaft. The umbilical seam is concave in lateral view. The whorl section is subquadrate with broadly rounded flanks, sharply rounded ventrolateral shoulders, and a broadly rounded venter. Strong primary ribs are prorsiradiate on the inner flanks and bear sharp umbilicolateral tubercles. These tubercles give rise to pairs of ribs that increase by intercalation on the outer flanks. There are six ventrolateral tubercles on the preserved part of the body chamber. They become increasingly stronger and more clavate in an adoral direction. Groups of three ribs loop between ventrolateral tubercles on either side of the venter with one equally strong nontuberculate rib between these groups. All ribs cross the venter with a broad convexity.

MAPS A2020a4 (fig. 9 O, P) is the final hook of the body chamber of a microconch. It has a concave umbilical wall and depressed, reniform whorl section (ratio of whorl breadth to whorl height is 1.38, accentuated by crushing). Four small, sharp bullae perch just outside the umbilical shoulder, and give rise to narrow sharp primary ribs in groups of three. At the adapical end of the fragment two of these ribs loop to a ventrolateral tubercle, but for most of the fragment, the ribs loop across the venter to umbilicolateral bullae on the other side, with some intercalated ribs arising at the ventrolateral shoulder, such that there is dense even ventral ornament.

MAPS A2020a7 (fig. 12F) is a fragment of a large body chamber with well­preserved flank ornament consisting of looped and intercalated ribs, and subspinose umbilicolateral and ventrolateral nodes.

DISCUSSION: The holotype of Jeletzkytes nodosus (Owen, 1852) (p. 581, pl. 8, fig. 4) is a macroconch that is finer ribbed than the present material, which can be matched, however, in other material from the Pierre Shale of the U.S. Western Interior. USNM 182522 (Cobban, 1974a: pl. 11, figs. 13, 14) differs from the present specimens in having many more ventrolateral tubercles on the phragmocone. Until the status of J. nodosus is resolved on the basis of the abundant material from the U.S. Western Interior, we refer the New Jersey specimens to Jeletzkytes cf. J. nodosus . The relationship with Acanthoscaphites praequadrispinosus Błaszkiewicz, 1980 (p. 38, pl. 19, figs. 2, 3, 6–8, pl. 20, figs. 1–3, 6–8, pl. 21, figs. 1–6) also bears further scrutiny.

OCCURRENCE: Jeletzkytes cf. J. nodosus is known from the lower phosphatic layer, basal Navesink Formation, Atlantic Highlands, New Jersey. Similar specimens are reported from the Coon Creek Tongue of the Ripley Formation in Tennessee; Saratoga Chalk, Arkansas; Nacatoch Sand, Chatfield County, northeast Texas; Baculites reesidei and B. jenseni zones, U.S. Western Interior; and the Vistula Valley, Poland.

Jeletzkytes cf. J. plenus (Meek, 1876)

Figure 13

compare:

Scaphites nodosus, var. plenus Meek, 1876: 429 , pl. 26, figs. la–c.

DESCRIPTION: USNM 455380 (fig. 13) is a plaster cast of a large macroconch with a phragmocone 65 mm in diameter (the original specimen is lost). The whorl section of the phragmocone is slightly compressed with broadly rounded flanks and a broadly arched venter. Primary ribs arise on the umbilical wall and strengthen across the inner flanks of the phragmocone, where they bear small bullate umbilicolateral tubercles. Each of these tubercles gives rise to one or two straight, prorsiradiate ribs; other ribs intercalate both high and low on the flanks. Single ribs or pairs of ribs link the umbilicolateral tubercles to 11 or 12 much stronger clavate ventrolateral tubercles on the last half­whorl of the phragmocone. Groups of two or three narrow ribs loop between the ventrolateral tubercles and cross the venter in a broad convexity, while one or two nontuberculate ribs of equal strength intercalate between the tuberculate groups.

The body chamber is incomplete, but its estimated complete length is 110 mm; it is slightly higher than wide (ratio of whorl breadth to whorl height at mid­shaft is 0.92). The umbilical wall is convex and the umbilical shoulder is straight in profile, so that most of the umbilicus of the spire is occlud­ ed. The inner flanks are broadly rounded, the outer flanks are flattened and convergent, and the venter is broadly rounded. Strong, distant, narrow prorsiradiate ribs arise on the umbilical wall; they are feebly concave across the umbilical shoulder and markedly prorsiradiate and concave on the flanks. Five strong umbilicolateral bullae are present on the shaft, and two weaker ones are present on the first part of the final hook (the rest of the body chamber is missing). Groups of two or three ribs link these bullae to much strong­ er clavate ventrolateral tubercles, with one to three nontuberculate ribs, some of them long intercalaries, between the tuberculate groups. An estimated 10 ventrolateral tubercles were present on the complete body chamber. Groups of two or three weakly convex ribs loop across the venter between ventrolateral tubercles, and are separated by one or two nontuberculate ribs.

DISCUSSION: This specimen differs from the holotype of Jeletzkytes plenus in being more compressed and more coarsely ribbed. J. plenus occurs in the Baculites eliasi and B. baculus zones in the Western Interior of the United States. Until the taxonomy of J. plenus is resolved on the basis of the abundant material from the U.S. Western Interior, we refer this specimen to J. cf. J. plenus .

OCCURRENCE:?Upper phosphatic layer, basal Navesink Formation, Atlantic Highlands, New Jersey.

Jeletzkytes criptonodosus Riccardi, 1983

Figure 12A, B

Jeletzkytes criptonodosus Riccardi, 1983: 28 , pl. 6, fig. 10, pl. 7, figs. 1, 2, pl. 8, figs. 7–9, text­figs. 25–27.

Jeletzkytes cf. criptonodosus Riccardi, 1983: 30 , pl. 11, figs. 1–21, text­figs. 28–31.

Jeletzkytes criptonodosus Riccardi, 1983 , Cobban and Kennedy, 1995: 31, figs. 6.4, 6.5, 22.5– 22.12, 23.1–23.5.

Jeletzkytes criptonodosus Riccardi, 1983 , Larson et al., 1997:81.

TYPE: The holotype is GSC 67104 , from the Belanger Member of the Bearpaw Formation of Saskatchewan, Canada (Riccardi, 1983: pl. 6, fig. 10, pl. 7, figs. 1, 2) .

DESCRIPTION: MAPS A2050a1 (fig. 12A, B) is a fragment with a maximum preserved whorl height of 35.5 mm; it is from the adapical end of the body chamber, and shows part of the final septum. A feeble umbilical bulge suggests that it is a small macroconch. The whorl section is compressed, with broadly rounded inner flanks, flattened, convergent outer flanks, and a broadly arched venter. There are six small umbilicolateral bullae, each of which gives rise to two or three narrow, delicate, prorsiradiate, weakly convex primary ribs that loop and zig­zag between small ventrolateral clavi. The poorly preserved venter is smooth to very feebly ribbed.

DISCUSSION: This fragment compares well with specimens of Jeletzkytes criptonodosus in the USGS collections from the Baculites grandis zone of the U.S. Western Interior as well as with the Canadian paratype figured by Riccardi (1983) as his pl. 8, figs. 7, 8 from the B. baculus zone of the southern part of the Canadian Western Interior.

OCCURRENCE: Lower Maastrichtian; middle part of Navesink Formation, from the oyster conglomerate, at Nut Swamp Brook, Middletown, Monmouth County, New Jersey; Baculites baculus zone in the Canadian Western Interior; Baculites grandis zone in the U.S. Western Interior; Prairie Bluff Chalk in Alabama; and Ripley Formation in Mississippi.

Figures

Fig. 9. A–F. Hoploscaphites pumilus (Stephenson, 1941). A, B. MAPS 2032a1; C, D. MAPS 2032a2; E, F. MAPS 2032a3; G–I. Discoscaphites gulosus (Morton, 1834), NJSM 16121, Inversand Pit, Sewell, Gloucester County, New Jersey. J–P. Jeletzkytes cf. J. nodosus (Owen, 1852). J–L. MAPS A2020a3; M, N. MAPS A2020a5; O, P. MAPS A2020a4. All specimens are from the lower phosphatic layer, Navesink Formation, Atlantic Highlands, unless otherwise stated. All figures are X1.

Fig. 10. Jeletzkytes cf. J. nodosus (Owen, 1852), MAPS A2020a1, macroconch, lower phosphatic level, Navesink Formation, Atlantic Highlands, New Jersey. Both figures are X1.

Fig. 11. Jeletzkytes cf. J. nodosus (Owen, 1852), MAPS A2020a2, microconch, lower phosphatic level, Navesink Formation, Atlantic Highlands, New Jersey. All figures are X1.

Fig. 12. A, B. Jeletzkytes criptonodosus Riccardi, 1983, MAPS A2050a1, Navesink Formation, bank of Nut Swamp Brook, near Middletown, Monmouth County. C–F. Jeletzkytes cf. J. nodosus (Owen, 1852), lower phosphatic layer, Navesink Formation, Atlantic Highlands, New Jersey. C. USNM 445247; D, E. MAPS A2020a6; F. MAPS A2020a7. All figures are X1.

Fig. 13. Jeletzkytes cf. J. plenus (Meek, 1876), USNM 455380, cast (original specimen is lost), macroconch,?upper phosphatic level, Navesink Formation, Atlantic Highlands, New Jersey. All figures are X1.