Sphenodiscus spp.

Landman, Neil H., 2004, Cephalopods From The Cretaceous / Tertiary Boundary Interval On The Atlantic Coastal Plain, With A Description Of The Highest Ammonite Zones In North America. Part 2. Northeastern Monmouth County, New Jersey, Bulletin of the American Museum of Natural History 2004 (287), pp. 1-107 : 55

Sphenodiscus spp. Figure 26

MATERIAL: There are four specimens that are too fragmentary for specific determination: AMNH 47119 , 47122 , and 50382 from the New Egypt / Hornerstown formational contact, AMNH loc. 3345, Parkers Creek , near Eatontown , Monmouth County, New Jersey ; and AMNH 47170 from the upper part of the New Egypt Formation , approximately 2–2.5 m below the base of the Hornerstown Formation , AMNH loc. 3350, a tributary of Hockhockson Brook , 0.7 km southwest of the intersection of Water Street and Tinton Avenue , Tinton Falls , Monmouth County, New Jersey .

DESCRIPTION: AMNH 47119 (fig. 26) and 47122 (not illustrated) are pieces of phragmocones. Both specimens are badly worn with etched sutures. Neither specimen bears any trace of nodes. AMNH 47119 consists of two fragments with a preserved whorl height of 86 mm. It is broken in half and shows an oxyconic whorl section. Part of the left side is covered with botryoidal swellings, possibly due to a parasitic infestation or more probably a diagenetic phenomenon. AMNH 47122 consists of four pieces, the largest of which has a preserved whorl height of 77 mm.

AMNH 47170 is a fragment of an internal mold of a large body chamber with most of the venter missing (not illustrated); it is 230 mm in maximum length. The whorl section is oxyconic with a sharply rounded venter. The specimen is poorly preserved but exhibits a weak swelling on the outer flanks.

DISCUSSION: These specimens are too fragmentary for specific identification. AMNH 47170 shows a weak swelling on the outer flanks indicating that it may be related to Sphenodiscus pleurisepta . The other speci­ mens do not show any evidence of nodes, suggesting kinship with S. lobatus .

OCCURRENCE: These specimens occur at the New Egypt /Hornerstown formational contact, AMNH loc. 3345, Parkers Creek, near Eatontown, and 2–2.5 m below the base of the Hornerstown Formation, AMNH loc. 3350, near Tinton Falls, Monmouth County, New Jersey.

SUBORDER ANCYLOCERATINA WIEDMANN, 1966

SUPERFAMILY TURRILITACEAE GILL, 1871

FAMILY BACULITIDAE GILL, 1871 [= EUBACULITINAE BRUNNSCHWEILER, 1966 ]

Figures

Fig. 26. Sphenodiscus sp. AMNH 47119, uppermost New Egypt Formation and basal Hornerstown Formation, AMNH loc. 3345, northwest of Eatontown, Monmouth County, New Jersey. A, Left lateral of phragmocone fragment; B. apertural of part of specimen. All figures are X1.