Discoscaphites Meek, 1871

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 : 71-92

Genus Discoscaphites Meek, 1871

TYPE SPECIES: Ammonites conradi Morton, 1834: 39 , pl. 16, fig. 3, by original designation.

Discoscaphites iris ( Conrad, 1858) Figures 34 , 35 , 36A–H, K–Q, S–Z, l–p , 37A–l , 38 , 39A–P , 41A–D

Scaphites iris Conrad, 1858: 335 , pl. 35, fig. 23.

Scaphites iris Conrad. Whitfield, 1892: 265 , pl. 44, figs. 4–7.

Discoscaphites iris (Conrad) . Stephenson, 1955: 134, pl. 23, figs. 23–30.

Discoscaphites iris ( Conrad, 1858) . Kennedy and Cobban, 2000: 183, fig. 5, pl. 3, figs. 3–35.

TYPE: The holotype is the original illustrated in Conrad, 1858: 335, pl. 35, fig. 23, labeled ANSP 50989, from the bluffs of Owl Creek, Tippah County, Mississippi. It is a partly crushed, fairly robust specimen, missing part of the phragmocone and hook and is attached to a piece of matrix. It is probably a microconch, but this is difficult to confirm because of the crushing. It retains part of its original, iridescent shell. The body chamber bears four rows of tubercles with the umbilicolateral tubercles being the most prominent. These tubercles show steep adapical sides and more gently sloping adoral sides.

MATERIAL: All of our specimens are from the top of the New Egypt Formation and base of the Hornerstown Formation, Parkers Creek, near Eatontown, northeastern Monmouth County, New Jersey. They are all internal molds and most of them are pieces of body chambers. The majority of specimens are from two clusters (1 and 2). Cluster 1 consists of a hardened chunk of chocolate brown clay peppered with large, green glauconite grains and contains 68 specimens, 28 of which are definitely identified as Discoscaphites iris ( AMNH 47332, 47336, 47337, 47339, 47341–47343, 47345–47349, 47351– 47361, 51057–51059, 51061, and 51062). The rest of the specimens are fragments. Some of these are difficult to identify at all whereas others hint at different species. Most of the specimens of D. iris in cluster 1 are slender with weak tubercles. Only one specimen ( AMNH 51059) is nearly whole but lacks the innermost whorls. AMNH 47360 is the next most complete specimen and consists of one­third whorl of an adult phragmocone and the complete body chamber. Of the 20 specimens that can be divided into macroconchs and microconchs, there are an almost equal number of each dimorph: 11 macroconchs and 9 microconchs. Cluster 2 consists of five specimens, all pieces of robust body chambers of microconchs ( MAPS A 2060a2, 3, AMNH 47308, 47363, and 51055).

DESCRIPTION: Like other scaphites, this species is strongly dimorphic. Dimorphs are distinguished by the shape of the adult body chamber. In side view, the umbilical shoulder of the body chamber is straight in macroconchs whereas it is curved in microconchs. Macroconchs are slightly larger than microconchs, but the size ranges of the dimorphs overlap. This species is characterized by four rows of tubercles: an umbilical or umbilicolateral row, depending on its position relative to the umbilical shoulder, a midflank row, and inner and outer ventrolateral rows. The umbilicolateral tubercles are the most prominent. The number of outer ventrolateral tubercles is equal to or slightly greater than the number of inner ventrolateral tubercles. As in other scaphite species, there is a range in variation from robust specimens with prominent tubercles (fig. 34A–D) to slender specimens with weak tubercles (fig. 35A–D). This variation is partly expressed in the ratio of whorl width to height at midshaft (table 8). We first describe the coarser specimens within each dimorph.

MACROCONCH DESCRIPTION

The most robust specimen is AMNH 51060, an internal mold, 38.6 mm in maximum diameter, consisting of a phragmocone and one­half of the adult body chamber (fig. 34A–D). The phragmocone is 30.9 mm in diameter. It is tightly coiled with a tiny umbilicus approximately 1.5 mm in diameter; the ratio of umbilical diameter to phragmocone diameter is 0.05. In side view, the venter of the phragmocone passes smoothly into the venter of the body chamber. Only the posterior one­half of the body chamber is preserved. The umbilical wall of the body chamber shows a slight bulge at approximately midshaft. There is only a small gap between the body chamber and the phragmocone.

section at adapical end. K–O. AMNH 47161. K, Right lateral; L, dorsal; M, ventral; N, left lateral; O, whorl cross section at adoral end. P–T. MAPS A 2053c2. P, Right lateral; Q, dorsal; R, ventral; S, left lateral; T, whorl cross section at adapical end. U–Y. Eubaculites carinatus ( Morton, 1834) , AMNH 47159, same locality as A–T. U, Right lateral; V, dorsal; W, ventral; X, left lateral; Y, whorl cross section at adapical end. All figures are X1.

The phragmocone is robust; the ratio of whorl width to height is 0.98 at the adapical end and decreases to 0.87 at the ultimate septum. The whorl section at the ultimate septum is compressed ovoid with maximum width at one­quarter whorl height. The umbilical wall is steep and inclined outward and the umbilical shoulder is gently rounded. In intercostal section, the flanks are broadly rounded and converge to the ventrolateral shoulder. The ventrolateral shoulder is sharply rounded and the venter is nearly flat.

The whorl section at approximately midshaft is robust with a ratio of 0.97 in both costal and intercostal section. The umbilical wall is steep and convex and the umbilical shoulder is broadly rounded. In costal section, the inner flanks are flat and inclined outward, attaining maximum width at one­quarter whorl height, the midflanks are nearly flat, and the outer flanks, between the inner and outer ventrolateral tubercles, are flat and converge toward the venter. In intercostal section, the inner flanks are well rounded and inclined outward, the midflanks are very broadly rounded, and the outer flanks are flat and converge toward the venter. The ventrolateral shoulder is sharply rounded and the venter is nearly flat.

Details of the ornament are better preserved on the left side of the specimen. On the adapical end of the phragmocone, relatively strong primary ribs are rectiradiate to slightly rursiradiate on the umbilical shoulder and inner flanks. They are moderately widely spaced and slightly raised at one­quarter whorl height, which is the site of future umbilicolateral tubercles. Ribs are straight and rectiradiate on the midflanks. Branching and intercalation occur at one­third whorl height. One primary rib shows a faint bulla at the position where midflank tubercles eventually develop, but these are hardly discernable at this point. Intercalation and branching occur at the site of the inner ventrolateral tubercles, which occur on the primary ribs and possibly on the secondary ribs, but it is difficult to establish this because of poor preservation. The ribs on the outer flanks are broad and gently inclined toward the venter. Each rib bears a prominent outer ventrolateral tubercle, which is matched on the other side of the venter. These tubercles are evenly spaced at distances of approximately 2 mm. Ribs on the venter are faint, straight, and swollen, joining pairs of tubercles. There are approximately 5 ribs/cm on the venter.

Toward the adoral end of the phragmocone, the ribs become less distinct, possibly because of poor preservation. The primary ribs swell into umbilicolateral tubercles on the inner flanks; the two most adoral tubercles are approximately 4.5 mm apart on the left side. A midflank tubercle also appears at the ultimate septum. Two inner ventrolateral tubercles are spaced approximately 7 mm apart near the base of the body chamber. The tubercles of the outer ventrolateral row become more widely spaced adorally. The distance between tubercles on the adoral end of the phragmocone is approximately 7 mm whereas the distance between tubercles on the adapical end is 2 mm. Near the base of the body chamber, these tubercles alternate on either side of the ventral margin.

The ornament on the body chamber consists of four rows of tubercles on low, broad, convex ribs. Tubercles of progressively more outward rows are disposed more adapically. There are two umbilicolateral tubercles preserved on the left side spaced approximately 7 mm apart, of which the most adoral tubercle is the most prominent one on the specimen. Two concave ribs appear to branch from it. The midflank row is more subdued and consists of four tubercles (including the one at the ultimate septum), which are spaced 5 mm apart at midshaft. The inner ventrolateral tubercles, of which there are four preserved (including the one at the ultimate septum), are evenly spaced at distances of 6 mm, and are slightly clavate. These three rows are equally distant from each oth­ er. In contrast, the outer ventrolateral row is closer to the inner ventrolateral row and is more subdued than it. There are four preserved tubercles in this row (including one at the ultimate septum) evenly spaced at distances of approximately 6 mm. As on the adoral part of the phragmocone, the tubercles alternate on either side of the ventral margin. Only part of the last suture is well enough preserved for drawing and shows the typical scaphitid elements U 1, U 2, and U 2 /L (fig. 41C).

There are several specimens that, although fragmentary, match AMNH 51060 in their robustness. We describe three specimens. AMNH 47367 is an internal mold of the adapical one­half of a robust body chamber and preserves the impression of part of the phragmocone (fig. 34Q–U). The whorl section at the base of the body chamber is well exposed and is compressed ovoid. The ratio of whorl width to height is 0.74 in intercostal section with maximum width at one­quarter whorl height. The umbilical wall is convex and the umbilical shoulder is fairly sharply rounded. The inner flanks are broadly round­ ed and inclined slightly outward, the midflanks are nearly flat and gently inclined toward the venter, and the outer flanks are flat and more sharply inclined toward the venter. The ventrolateral shoulder is fairly sharply rounded and the venter is flat. Width expands markedly at midshaft due to the development of a large umbilicolateral tubercle. The ratio of whorl width to height at midshaft is approximately 0.97 in costal section.

The ornament on a peel of a part of the phragmocone shows slightly flexuous prorsiradiate ribs. Ribs are straight on the inner flanks, swelling into weak umbilicolateral bullae, and swing forward on the midflanks; one rib develops into a midflank bulla. Ribs intercalate and bend forward toward the inner ventrolateral tubercles, which are small and bullate. Ribs intercalate again and bend forward toward the outer ventrolateral tubercles of which there are 16 on the peel. These tubercles are approximately evenly spaced at distances of 1.25 mm. They are paired across the venter and are connected by weak ribs, which show a very slight adoral projection. There are approximately 8 ribs/cm on the venter based on an average distance of 1.25 mm between ribs.

The ornament on the body chamber is better preserved on the left side. There are four rows of tubercles; the largest tubercle is the umbilicolateral tubercle at midshaft. The distances between tubercle rows at midshaft starting with the umbilicolateral row is 7 mm, 6 mm, and 4.75 mm. The distance between outer ventrolateral tubercles on either side of the venter is 5 mm.

AMNH 47365 is an internal mold consisting of a fragment of the adoral part of the phragmocone, and the flanks and part of the venter of the adapical one­quarter of the body chamber (fig. 34N–P). It retains part of the inner whorls showing the ontogenetic transformation from a depressed, kidneyshaped whorl section to a more compressed, rounded whorl section. The body chamber is robust and bears inner and outer ventrolateral and umbilical tubercles; the midflank tubercles are very weak. The last suture of the phragmocone (fig. 41A, B) shows a narrow, asymmetrically bifid first lateral lobe (L). The dorsal suture of the inner whorls shows a narrow, symmetrically trifid lobe.

MAPS A 2060a1 is most of a body chamber minus the hook (fig. 34E–H). The umbilical shoulder shows a conspicuous bulge. The whorl section at the base of the body chamber is well preserved. It is compressed ovoid with maximum width at one­third whorl height; the ratio of whorl width to height is 0.81 in costal section. The umbilical wall is steep and convex and the umbilical shoulder is fairly abruptly rounded. The inner flanks are broadly rounded and inclined outward, the midflanks are flat and gently converge toward the venter, and the outer flanks are broadly rounded and converge more steeply toward the venter. The ventrolateral shoulder is fairly abruptly rounded and the venter is flat. Width expands more rapidly than height and the ratio of whorl width to height at midshaft is 0.87 in intercostal section and 1.05 in costal section.

51059. A, Right lateral; B, apertural; C, ventral; D, left lateral. E–G. AMNH 47348. E, Right lateral; F, ventral, G, left lateral. H–L. AMNH 47360. H, Right lateral; I, apertural; J, ventral; K, left lateral; L, peel, left lateral. M–P. AMNH 47357. M, Right lateral; N, apertural; O, ventral; P, left lateral. Q– T. AMNH 51061. Q, Right lateral; R, apertural; S, ventral; T, left lateral. U–X. AMNH 47361. U, Right lateral; V, apertural; W, ventral; X, left lateral. Y–Z, a, b. AMNH 51062. Y, Right lateral; Z, apertural; a, ventral; b, left lateral. c–f. AMNH 47358. c, Left lateral; d, apertural; e, ventral; f, left lateral. All specimens X1.

There are four rows of tubercles with the umbilicolateral tubercles being the largest and the outer ventrolateral tubercles being the smallest. The distance between umbilicolateral tubercles at midshaft is 6 mm. The midflank tubercles are approximately evenly spaced at distances of 5–6 mm. The inner ventrolateral tubercles are approximately evenly spaced at distance of 5.0– 6.5 mm, although they show a slightly wider spacing at midshaft (7–7.5 mm). There are 11 outer ventrolateral tubercles evenly spaced at distances of 5–6 mm. They are matched on either side of the venter. A strong prorsiradiate rib links an inner and outer ventrolateral tubercle and extends onto the venter on the right side near the adoral end of the specimen. The distance between tubercle rows at midshaft starting with the umbilicolateral row is 5 mm, 6 mm, and 5 mm.

AMNH 51059 is representive of the more slender and more weakly ornamented variants characteristic of cluster 1 (fig. 35A–D). It is a nearly complete macroconch approximately 33.9 mm in diameter. The phragmocone is slightly crushed in on the adoral end on the left side and is missing the innermost whorls. Part of the venter is missing and part of the flanks are obscured by matrix on the right side on the adapical end of the body chamber. This damage may be due to a lethal injury. The ventral and right side of the apertural margin are broken off.

The phragmocone is relatively involute. The umbilicus is difficult to measure because it is covered with matrix on the left side and is missing altogether on the right side; it is approximately 3.5 mm in diameter. The phragmocone is 23.5 mm in diameter; the ratio of umbilical diameter to phragmocone di­

TABLE 8 Measurements of Discoscaphites iris ( Conrad, 1858) a

ameter is 0.15; the ratio of umbilical diameter to shell diameter is 0.10. In side view, the venter of the phragmocone passes smoothly into the venter of the body chamber, describing a broad arc. There is no visible gap between the phragmocone and the body chamber. The apertural margin is slightly flexuous and the apertural angle is very low (27°). The umbilical seam of the body chamber is straight with a slight bulge. The body chamber is approximately 0.5 whorls long.

The whorl section of the phragmocone is compressed ovoid. The ratio of whorl width to height in intercostal section at the point of exposure and at the ultimate septum is 0.66 and 0.63, respectively. At the ultimate septum, the umbilical wall is steep and convex and the umbilical shoulder is sharply round­ ed. The flanks are very broadly rounded to flat with maximum width at one­quarter whorl height. They gently slope toward the venter but become more steeply inclined between the inner and outer ventrolateral tubercles. The ventrolateral margin is sharply rounded and the venter is flat with a slightly raised midline.

The whorl section of the most adapical part of the body chamber is similar to that of the phragmocone, but the body chamber becomes more swollen at midshaft. The ratio of whorl width to height at midshaft is 0.84 and 0.92 in intercostal and costal sections, respectively. The umbilical wall is steep and convex and the umbilical shoulder is fairly abruptly rounded. The inner flanks are broadly rounded and inclined outward, the midflanks are nearly flat and gently converge toward the venter, and the outermost flanks between the inner and outer ventrolateral tubercles are broadly rounded and more steeply inclined toward the venter. The ventrolateral margin is fairly sharply rounded and the venter is very broadly rounded. The body chamber tapers adorally with a reduction in whorl width and height. The whorl width and height at the point of recurvature are 11.5 mm and 12.8 mm, respectively; the ratio of whorl width to height is 0.90.

The ornament on the phragmocone is poorly preserved and consists of prorsiradiate ribs and inner and outer ventrolateral tubercles. Branching and intercalation occur at two­thirds whorl height. Near the adoral end of the phragmocone, the ribs are bullate on the inner flanks at the site of the future umbilicolateral tubercles. Midflank tubercles are not present although this may be due to poor preservation. The inner ventrolateral tubercles, of which there are 16 on the exposed phragmocone, occur on every rib. They are evenly spaced at distances of 1.5 mm on the adapical end of the phragmocone, becoming more widely spaced toward the adoral end; the distance between the two most adoral tubercles is 3 mm. The outer ventrolateral tubercles are smaller than the inner ventrolateral tubercles but are more distinct, numerous, and more closely spaced. There are 27 of them on the exposed phragmocone. They are tiny and evenly spaced at distances of approximately 1 mm on the adapical end of the phragmocone, becoming abruptly larger and more widely spaced on the adoral onethird of the phragmocone. The distance between the two most adoral tubercles is approximately 2 mm. Some tubercles are matched and others are not on either side of the ventral margin. A few ribs are present on the venter on the adapical part of the phragmocone but most of the venter is smooth.

Ribs are not well defined on the posterior part of the body chamber but become more conspicuous on the adoral one­third. There are six strongly prorsiradiate, moderately widely spaced ribs on the hook, which become more closely spaced toward the aperture. The venter is smooth. There are four rows of tubercles. Three umbilicolateral tubercles are preserved on the left side at approximately one­quarter whorl height. They are evenly spaced at distances of 4.5 mm. The middle tubercle is the most prominent tubercle on the specimen. The midflank tubercles occur at midwhorl height and are smaller and more numerous than the umbilicolateral tubercles. The largest and most widely spaced midflank tubercles (5.5 mm apart) occur at midshaft; they diminish in size and spacing toward the aperture. The inner ventrolateral tubercles are slightly more prominent than the midflank tubercles. Eleven inner ventrolateral tubercles are preserved on the body chamber on the left side. They are fairly evenly spaced at distances of 5 mm on the shaft but become more closely spaced toward the aperture. The outer ventrolateral tubercles are smaller and less distinct than the inner ventrolateral tubercles. There are 11 outer ventrolateral tubercles preserved on the body chamber on the left side, equal to the number of inner ventrolateral tubercles. They are fairly evenly spaced at distances of approximately 4 mm. Tubercles are slightly offset from one side of the venter to the other. The distance between tubercle rows at midshaft starting with the umbilicolateral row is 5.5 mm, 4 mm, and 2.5 mm. A composite suture is illustrated at a whorl height of 7.9 mm (fig. 41D). The first lateral saddle (E/L) and lobe (E) are both asymmetrically bifid.

AMNH 47360 consists of the adoral end of the phragmocone and body chamber, with the venter on the adoral part of the shaft missing and the right side of the specimen worn (fig. 35H–L). The impression of the left side of the specimen is preserved in matrix. The body chamber is slightly more than 0.5 whorls long. The umbilical shoulder is weakly swollen in side view. The whorl section at the base of the body chamber is compressed ovoid with a ratio of whorl width to height of 0.69. The body chamber is swollen at midshaft with a ratio of whorl width to height of 0.75 in intercostal section. The umbilical wall is steep and convex and the umbilical shoulder is fairly abruptly rounded. The inner flanks are broadly rounded and inclined outward, the midflanks are nearly flat and gently converge toward the venter, and the outer flanks are broadly rounded and converge more steeply toward the venter. The ventrolateral shoulder is fairly abruptly rounded and the venter is very broadly rounded. The whorl section at the aperture is less compressed than that at midshaft with a ratio of whorl width to height of 0.98.

The ornament on the body chamber is better preserved on the left side. There are four rows of tubercles that occur on poorly defined ribs. Ribs swing backward on the inner flanks, forward on the midflanks, and back again on the outer flanks. Very fine ribs are visible on a peel made from the impression of the left side of the specimen. Intercalation and branching occur at the umbilicolateral tubercles or at the equivalent whorl height. Pairs of ribs loop between umbilicolateral and midflank tubercles at midshaft. There are six umbilicolateral tubercles that extend to the aperture. They are unevenly spaced with the maximum distance between the two most adoral tubercles of approximately 6.5 mm. Nor are they of equal strength; the next to last tubercle is the most prominent tubercle on the specimen. A row of five tubercles occurs on the midflanks with a distance of approximately 9 mm between the two most adoral tubercles. There are eight slightly more prominent inner ventrolateral tubercles that are approximately evenly spaced at distances of 5–7 mm. The outer row of ventrolateral tubercles, which extends to the aperture, is incomplete due to postmortem breakage, but there would have originally been at least 10 tubercles, two more than the number of inner ventrolateral tubercles. The distance between the two most adoral tubercles is 5 mm. The distance between tubercle rows at midshaft starting with the umbilicolateral row is 5 mm, 4 mm, and 4 mm.

There are nine other macroconchs in cluster 1, of which we describe four, but all are more fragmentary than AMNH 47360 and AMNH 51059. AMNH 51061 is an internal mold of one­half of a compressed body chamber (fig. 35Q–T). Ribs are present in addition to the four rows of tubercles and are conspicuous on the right side. Ribs swing slightly backward on the umbilical shoulder and then forward on the inner one­half of the flanks. They become bullate at one­quarter whorl height, where they bifurcate and join the midflank tubercles. Straight to weakly convex ribs link the midflank to the inner ventrolateral tubercles on the adoral part of the shaft and hook. Ribs become increasingly prorsiradiate adorally and connect the inner and outer ventrolateral tubercles. There are two ribs on the venter near the apertural margin. They cross the venter with a slight adoral projection and join pairs of outer ventrolateral tubercles on the opposite side of the venter. The distance between tubercle rows at midshaft starting with the umbilicolateral row is 4.5 mm, 5 mm, and 3.5 mm.

AMNH 47361 is one­half of a body chamber with most of the right side worn away (fig. 35U–X). The apertural margin is slightly flexuous with a constriction. The whorl section at the aperture is subquadrate with a ratio of whorl width to height of 0.94. All four rows of tubercles are present, with one of the umbilicolateral tubercles being the most prominent. The most complete row of tubercles is the inner ventrolateral row of which there are 11 tubercles on the body chamber including one on the apertural margin. The spacing between rows of tubercles at midshaft starting with the umbilicolateral row is 5.5 mm, 5.5 mm, and 4.5 mm.

AMNH 47357 is most of a robust body chamber minus the hook, although the adapical end is not well preserved (fig. 35M–P). The whorl section at midshaft is compressed ovoid with maximum width at one­quarter whorl height. The intercostal ratio of whorl width to whorl height is 0.83. The umbilical wall is steep and subvertical and the umbilical shoulder is fairly abruptly rounded. The inner flanks are broadly rounded, the midflanks are nearly flat and gently converge to the venter, and the outer flanks are broadly rounded and converge more steeply toward the venter. The ventrolateral shoulder is fairly abruptly rounded and the venter is nearly flat. The body chamber is covered with swollen, poorly defined prorsiradiate ribs bearing four rows of tubercles. There are three umbilicolateral tubercles perched just outside the umbilical shoulder. The middle one of these tubercles points slightly backward and is the most prominent tubercle on the specimen. There are five midflank, six inner ventrolateral, and eight outer ventrolateral tubercles. The outer ventrolateral tubercles are paired on either side of the venter and are joined by weak swollen ribs.

AMNH 47355 is the middle portion of a flat sided body chamber minus part of the venter (fig. 36A–D). Ribs are rectiradiate and nearly straight on the adapical end of the specimen becoming prorsiradiate and weakly concave toward the adoral end. All four rows of tubercles are present on the left side. A groove occurs on the flanks on the right side at one­third whorl height and represents a repaired injury. As a result, the midflank row of tubercles is not present on this side but the ribs are better developed.

MICROCONCH DESCRIPTION

Most of the robust microconchs comprise cluster 2 ( MAPS A 2060a2, A2060a3, AMNH 47308, 47363, and 51055). AMNH 47363 is an internal mold of a body chamber with most of the venter of the shaft worn away and part of the hook missing (fig. 38A– D). There is an impression of the phragmocone on the dorsum. The specimen retains some patches of iridescence, probably because a very thin layer of shell material is preserved. In side view, the umbilical shoul­ der forms a curve, which is the same as that of the venter. The apertural margin shows a constriction.

The body chamber grows rapidly in width in passing from the base to midshaft. Thereafter, the width remains nearly the same, but the height diminishes slightly to the point of recurvature. The ratio of whorl width to height in intercostal section is 0.70, 0.95, and 1.03 at the base of the body chamber, midshaft, and point of recurvature, respectively. The umbilical wall is nearly flat and subvertical at midshaft and the umbilical shoul­ der is fairly abruptly rounded. The flanks are broadly rounded and gently inclined toward the venter, becoming more steeply inclined at three­quarters whorl height.

The ornament on a peel of part of the phragmocone shows inner and outer ventrolateral tubercles linked by prorsiradiate ribs. The number of outer ventrolateral tubercles exceeds the number of inner ventrolateral tubercles. The outer ventrolateral tubercles are tiny and evenly spaced at distances of approximately 1.25 mm. The tubercles are paired on either side of the venter and linked by ribs showing a very slight adoral projection. There are approximately 8 ribs/cm on the venter based on an average distance of 1.25 mm between ribs.

The ornament on the body chamber consists of four rows of tubercles; some of these tubercles occur on swollen broad ribs. Two straight rectiratidiate ribs occur on the adapical end of the body chamber on the left side. There are four umbilicolateral tubercles perched on the umbilical shoulder. They are evenly spaced at distances of 6 mm and extend to the aperture. The two middle ones are the most prominent tubercles on the specimen. There are seven midflank tubercles that are evenly spaced at distances of approximately 6 mm and eight inner venterolateral tubercles, although some of these are worn away at midshaft. The row of outer ventrolateral tubercles is only preserved on the adapical portion of the specimen.

MAPS A 2060a2 is most of a robust body chamber minus part of the hook with the impression of the inner whorls (fig. 38E–H). The whorl section at the base of the body chamber is compressed ovoid with maximum width at one­quarter whorl height in costal and intercostal section; the ratio of whorl width to whorl height is 0.81 in costal section. The umbilical wall is steep and convex and the umbilical shoulder is fairly abruptly rounded. The inner flanks are nearly flat and inclined slightly outward, the midflanks are nearly flat and gently converge toward the venter, and the outer flanks are broadly rounded and converge more steeply toward the venter. The ventrolateral shoulder is fairly abruptly rounded and the venter is narrow and flat. The whorl width and height expand gradually into the body chamber. The whorl section at midshaft is subquadrate with maximum width at the umbilical shoulder in both costal and intercostal section. The ratio of whorl width to height in intercostal section is 1.05. The umbilical wall is broad, weakly convex to nearly flat, and inclined slightly outward; the umbilical shoulder is abruptly rounded. The flanks are broadly rounded and gently converge toward the venter, becoming more steeply convergent near the inner ventrolateral tubercles. The ventrolateral shoul­ der is fairly abruptly rounded and the venter is flat.

The ornament on a peel of part of the phragmocone shows rows of inner and outer ventrolateral tubercles. Straight prorsiradiate ribs join the inner and outer ventrolateral tubercles. The outer ventrolateral tubercles are tiny and are evenly spaced at distances of approximately 1.25 mm. There are approximately 1.5 times as many outer as inner ventrolateral tubercles. The outer ventrolateral tubercles are matched on either side of the venter on the adoral one­half of the peel and alternate on the adapical one­half. Ribs cross the venter with a very slight adoral projection and link paired or offset outer ventrolateral tubercles. There are approximately 8 ribs/cm based on an average distance of 1.25 mm between ribs.

On the body chamber, four rows of tuber­ cles are prominent and occur on fairly strong, swollen prorsiradiate ribs. Ribs bifurcate and swing forward from the umbilical tubercles connecting the midflank and inner ventrolateral tubercles. Ribs weaken or disappear between the inner and outer ventrolateral tubercles. The most prominent tubercles are the umbilical tubercles, followed by the inner ventrolateral tubercles, the midflank tubercles, and the outer ventrolateral tubercles. As counted on the right side, there are four umbilical tubercles spaced at distances of 4.5–6 mm, seven midflank tubercles spaced at distances of 3.5–5 mm, seven inner ventrolateral tubercles spaced at distances of 5–7 mm, and eight outer ventrolateral tubercles spaced at distances of 5.5 mm. The distance between tubercle rows at midshaft starting with the umbilical row is 4 mm, 4.5 mm, and 3.5 mm. The spacing between paired ventrolateral tubercles on either side of the venter ranges from 3 mm at the adapical end to 4.5 mm at the adoral end of the specimen.

MAPS A 2060a4 is most of a robust body chamber and adoral part of a phragmocone attached to a siderite nodule (fig. 34I, J). The ventral and left side of the hook are missing. The whorl section is compressed ovoid at midshaft with an intercostal ratio of whorl width to height of 1.08. The maximum width is at the umbilical shoulder. The midflanks are broadly rounded and gently converge toward the venter, and the outer flanks are nearly flat and converge more steeply toward the venter. The ventrolateral shoulder is fairly abruptly rounded and the venter is nearly flat.

Four rows of tubercles occur on swollen, poorly defined prorsiradiate ribs. The right side preserves the ornamentation better. There are three umbilical tubercles on the body chamber extending to the aperture. The middle tubercle is the most prominent tubercle on the specimen and exhibits a steep adapical and more gently sloping adoral side. There are seven midflank tubercles that occur just dorsal of midwhorl height. They are evenly spaced at distances of 4.5–5.5 mm except near the aperture where there is an increase (8 mm) and then a decrease (4.5 mm) in spacing. A row of 11 inner ventrolateral tubercles (one is presumed to have been present but is missing due to breakage) occurs at two­thirds whorl height and extends to the aperture. The tubercles occur at approximately equal distances of 4.5–5.5 mm. Only part of the outer ventrolateral row of tubercles is preserved. There are eight outer ventrolateral tubercles versus five inner ventrolateral tubercles on the adapical one­half of the body chamber. The distance between tubercle rows at midshaft, starting with the umbilical row, is 4.25 mm, 4.5 mm, and 3.5 mm. The distance between outer ventrolateral tubercles on either side of the venter is 4.75 mm.

The microconchs in cluster 1 represent more compressed forms. The best preserved microconch in cluster 1 is AMNH 51057, an internal mold of a body chamber with the remnant of the inner whorls (fig. 37A–D). It is 30.2 mm in maximum diameter. Adhering matrix on the left side obscures the umbilical margin but on the right side, the umbilical margin is tightly curved in side view. The body chamber is compressed and gradually expands in height and width to the aperture, which shows a constriction. The ratio of whorl width to height at midshaft is 0.75 in intercostal section. The umbilical wall is flat and inclined outward and the umbilical shoulder is sharply rounded. The flanks are nearly flat and subparallel, becoming more steeply inclined toward the venter at threequarters whorl height. The ventrolateral shoulder is sharply rounded and the venter is flat.

The ornament on the body chamber consists of four rows of tubercles, some of which occur on weak, broad, straight to arcuate ribs. The only well­defined rib is just adapical of the apertural margin. Five umbilicolateral tubercles are perched on the umbilical shoulder and extend to the aperture. The four most adoral tubercles are evenly spaced at distances of approximately 4 mm. The midflank tubercles begin as bullate swellings, becoming more tuberculate at midshaft, and extend to the aperture. There are 12 inner ventrolateral tubercles that become more closely spaced adorally. The spacing between the two most widely spaced tubercles is 5 mm and the spacing between the two most closely spaced tubercles is 3 mm. There are 19 outer ventrolateral tubercles, that is, 1.6 times the number of inner ventrolateral tu­ bercles. They are most widely spaced (4.5 mm) at midshaft and most closely spaced (2 mm) near the base of the body chamber. The ventrolateral tubercles are generally offset from one side of the venter to the other. The distance at midshaft between the four rows of tubercles, starting with the umbilicolateral row, is 3.5 mm, 3.5 mm, and 2.5 mm.

There are eight other microconchs in cluster 1, all of them relatively compressed. We describe three. AMNH 51058 is an internal mold of the adoral one­half of a body chamber (fig. 37I–L). The right side is partly covered with matrix, possibly obscuring a hole in the shell. The whorl section at midshaft is nearly subquadrate with a ratio of whorl width to height of 0.95 in intercostal section. All four rows of tubercles are well developed with the umbilical tubercles being the largest, least numerous, and most widely spaced and the outer ventrolateral tubercles being the smallest, most numerous, and most closely spaced.

AMNH 47356 is the middle portion and part of the hook of a body chamber (fig. 37Q–T). The whorl section at midshaft is compressed ovoid with maximum width at the umbilical shoulder in costal section and at one­third whorl height in intercostal section. The intercostal ratio of whorl width to whorl height is 0.93. The tubercles occur on poorly defined, swollen prorsiradiate ribs. The strongest tubercles are the umbilical tubercles followed by the inner ventrolateral tubercles. The distance between tubercle rows at midshaft, starting with the umbilical row, are 4 mm, 5.5 mm, and 3 mm. The distance between outer ventrolateral tubercles on either side of the venter at midshaft is 4 mm.

AMNH 47353 is part of the body chamber of a fairly compressed specimen (fig. 37c–f). The ornament consists of fairly strong prorsiradiate ribs with four rows of tubercles. However, the spacing of the tubercle rows differs from that in most other specimens. The umbilical row is perched on the umbilical shoulder, but the midflank and ‘‘inner ventrolateral row’’ occur just above and below midwhorl height, respectively. The ‘‘inner’’ and outer ventrolateral rows are spaced widely apart. The distance between rows on the middle of the specimen starting with the umbilical row is 3 mm, 3.5 mm, and 5 mm. The distance between ventrolateral tubercles on either side of the venter is 3 mm.

AMNH 47105 from AMNH loc. 3345 (but not from cluster 1) is most of a body chamber minus the hook and venter (fig. 39A–D). There is some iridescent shell on the umbilical wall on the right side. The base of the body chamber is well preserved. It is compressed ovoid with a ratio of whorl width to height of 0.63 in intercostal section. The umbilical wall is steep and convex and the umbilical shoulder is sharply rounded. The flanks are flat and nearly subparallel. The ventrolateral shoulder is fairly abruptly rounded and the venter is nearly flat.

There are six umbilical tubercles perched on the umbilical shoulder. They are arcuate and evenly spaced at distances of approximately 2.5 mm. Ribs arise in pairs from these tubercles and are prorsiradiate on the flanks. The more adoral rib of each pair is weaker and convex and the more adapical rib is stronger and concave to straight, and links to a midflank tubercle. Weaker, finer ribs intercalate between the umbilical tubercles. The midflank tubercles are bullate and less prominent than the umbilical tubercles and are spaced at distances of 3.5–4 mm. Due to the erosion of the venter, some of the inner ventrolateral tubercles and all of the outer ventrolateral tubercles are missing.

AMNH 51056 is the adapical one­half of a body chamber (fig. 39E–H). It is from AMNH loc. 3345 (but not cluster 1) and resembles AMNH 47337 (fig. 37i–l) in having nearly flat flanks. The whorl section at midshaft is compressed subquadrate with a ratio of whorl width to height of 0.84. The umbilical tubercles are arcuate with steep adapical sides and more gently inclined adoral sides. Swollen, arcuate ribs link the midflank tubercles to the inner ventrolateral tubercles, which, after the umbilical tubercles, are the second most prominent tubercles on the specimen. These tubercles also exhibit steep adapical sides and more gently sloping adoral sides. The outer ventrolateral tubercles are less prominent than the inner ventrolateral tubercles. The distance between tubercle rows at midshaft, starting with the umbilical row, is 4.25 mm, 4 mm, and 2.5 mm. The outer ventrolateral tubercles are very closely spaced on either side of the venter, approximately 3 mm apart. Based on the regular spacing of tubercles on most of the specimen, a single outer ventrolateral tubercle, one in each row on either side of the venter, seems to have been skipped during growth. A shallow groove appears on the midventer at this point suggesting a repaired injury.

DIMORPH INDETERMINATE

There are many specimens, most from cluster 1, that are too fragmentary to determine the dimorph. We describe two of the more complete specimens.

AMNH 47349 is the shaft of a fairly compressed, although slightly crushed body chamber, probably of a macroconch ( Fig. 36S–V ). The flanks are nearly flat and gently converge toward the venter, as in AMNH 47337 and 51056. The ribs are weak, prorsiradiate, and slightly flexuous. All four rows of tubercles are present with the outer and inner ventrolateral rows being very closely spaced to one another. The distances between rows at midshaft, starting with the umbilicolateral row, are 3.5 mm, 4 mm, and 2.25 mm. The distance between ventrolateral tubercles on either side of the venter is also small, approximately 3 mm.

AMNH 47368 is the adoral half of the body chamber of a fairly robust specimen, probably a macroconch (fig. 39K–M). It is from AMNH loc. 3345 but not from cluster 1. The right side is worn away. A small piece of the phragmocone is still attached. This piece and part of the body chamber retain some shelly iridescence. The ornament consists of four rows of tubercles but the spacing between them differs from that in most other specimens. Two umbilical tubercles occur on the umbilical shoulder, the adapical one of which is the most prominent tubercle on the specimen. Two tubercles occur on the innermost flanks near the aperture. A more prominent row of tubercles occurs slightly ventral of midwhorl height. These are linked by short arcuate ribs to a row of ventrolateral tubercles. The distance between tubercle rows near the aperture, starting with the umbilical row and excluding the row of only two tubercles, is 3 mm, 3 mm, and 4 mm.

DISCUSSION: Discoscaphites iris is charac­ terized by four rows of tubercles borne on weak to coarse ribs. In macroconchs, the distance between the umbilical and midflank tubercles is equal to or slightly greater than that between the midflank and inner ventrolateral tubercles, which is greater than the distance between the inner and outer ventrolateral tubercles. Because the whorl height in microconchs is smaller than that in macroconchs, the spacing of tubercles is slightly different. The distance between the umbilical and midflank tubercles is approximately equal to or slightly less than that between the midflank and inner ventrolateral tubercles, which is greater than the distance between the inner and outer ventrolateral tubercles. The number of outer ventrolateral tubercles on the body chambers of macroconchs is approximately 1–1.5 times the number of inner ventrolateral tubercles. The most prominent tubercles are the umbilicolateral tubercles, followed by the inner ventrolateral tubercles. The midflank and outer ventrolateral tubercles are equally small.

Discoscaphites iris was originally described from the Owl Creek Formation, Tippah County, Mississippi, by Conrad (1858: 335, pl. 35, fig. 23). Kennedy and Cobban (2000) described and illustrated many additional specimens from this locality, reflecting a range of variation from slender to robust forms. The strength of the tubercles covaries with the degree of inflation. The holotype is a robust specimen, and several other specimens, presumably part of Conrad’s original material, now housed in the Academy of Natural Sciences of Philadelphia, represent both slender and robust forms.

As in other scaphites, it is tempting to distinguish the end members of this kind of morphological series and assign them different species names. However, there are many intermediaries and choosing the dividing line is difficult and arbitrary. As a result, we prefer to regard all of our specimens as conspecific.

Kennedy and Cobban (2000: 185, fig. 6, pl. 1, figs. 1–11) described Discoscaphites sphaeroidalis Kennedy and Cobban, 2000 , from the Owl Creek Formation in northeastern Mississippi. According to them, this species is close to D. iris but differs from it in having a more inflated shape and more strongly ribbed phragmocone. Many of the coarsely ornamented specimens in our collection resemble the holotype of D. sphaeroidalis , but none of them retains enough of the phragmocone to detect the presence of unusually strong ribbing diagnostic of this species. Therefore, we refer all the robust specimens in our collection to D. iris .

Discoscaphites iris differs from Discoscaphites conradi ( Morton, 1834) and Discoscaphites gulosus ( Morton, 1834) in having four rows of tubercles. In addition, the outer ventrolateral tubercles are more widely spaced in Discoscaphites iris than in Discoscaphites conradi . Discoscaphites iris differs from Discoscaphites minardi Landman et al., 2004 , chiefly in that the midflank tubercles are sharp and well developed in D. iris whereas they are weak and bullate, if they exist at all, in D. minardi .

OCCURRENCE: Upper part of the New Egypt Formation and as reworked material at the base of the Hornerstown Formation, Parkers Creek, near Eatontown, northeastern Monmouth County, New Jersey. Elsewhere in New Jersey, this species occurs in the upper part of the New Egypt Formation in the Crosswicks Creek Drainage, southwestern Monmouth County (Landman et al., in prep. b), and at the top of the Tinton Formation and as reworked material at the base of the Hornerstown Formation, Manasquan River Drainage, central Monmouth County (Landman et al., in prep. a). Discoscaphites iris is also known from the upper part of the Severn Formation, Kent and Anne Arundel Counties, Maryland ( Landman et al., 2004). On the Gulf Coastal Plain, it occurs in the Owl Creek Formation and as reworked material at the base of the Clayton Formation in Mississippi, Tennessee, and Missouri ( Stephenson, 1955; Sohl, 1960, 1964; Kennedy and Cobban, 2000). It is the name bearer of the Discoscaphites iris Zone on the Gulf and Atlantic Coastal Plains, which represents the upper part of the upper Maastrichtian, corresponding to the upper part of calcareous nannofossil Subzone CC26b.

Discoscaphites minardi Landman et al.,

2004

Figures 39Q–T , 40A–D, J–P

TYPE: The holotype is AMNH 47288, a macroconch, from AMNH loc. 3252 from the top of the Severn Formation, Betterton quadrangle, Kent County, Maryland.

MATERIAL: There are four specimens: two macroconchs ( MAPS A 2059b2 and AMNH 47307) and one microconch ( AMNH 47305) from AMNH locs. 3346 and 3347, from the upper part of the New Egypt Formation 1.5– 2 m below the base of the Hornerstown Formation, near Eatontown, Monmouth County, New Jersey, and one microconch ( AMNH 47369) from AMNH loc. 3345 from the New Egypt /Hornerstown formational contact, near Eatontown, Monmouth County, New Jersey.

MACROCONCH DESCRIPTION

AMNH 47307 is the adoral one­half of a body chamber with part of the venter and aperture missing (fig. 40J–M). The flanks are nearly flat and subparallel and the venter is broadly rounded. The whorl section at the aperture is subquadrate with a ratio of whorl width to height of 0.87. The dorsal projection of the aperture is preserved. The ornament is subdued with faint, straight, widely spaced prorsiradiate ribs that become more closely spaced near the apertural margin. Rows of umbilicolateral and inner and outer ventrolateral tubercles are present as well as a row of weak midflank swellings. The umbilicolateral tubercles are spaced at distances of 5 mm at midshaft. Ten radial swellings are visible on the midflanks on the left side of the fragment and extend to the aperture. The distance between midflank swellings at midshaft is 3 mm. There are an equal number of inner and outer venterolateral tubercles on the hook—seven in each row, as counted on the left side; both rows extend to the aperture. The distance between tubercle rows at midshaft, starting with the umbilicolateral row and including the midflank row, is 4 mm, 5 mm, and 4.5 mm.

MAPS A 2059b2 from AMNH loc. 3347 is most of a body chamber minus the ventral one­half of the hook (fig. 40A–D). The umbilical shoulder shows a bulge in side view. There is the impression of the phragmocone. The base of the body chamber is well preserved and is compressed ovoid with a ratio of whorl width to height of 0.55. The umbilical wall is steep and convex and the umbilical shoulder is fairly abruptly rounded. The inner flanks are flat and slightly divergent, the midflanks are nearly flat and subparallel, and the outer flanks are very broadly rounded and gently converge to the venter. The ventrolateral shoulder is fairly abruptly rounded and the venter is broadly rounded. The whorl width expands more rapidly than the whorl height and the ratio of whorl width to height at midshaft is 0.68.

Ribs are straight on the inner flanks at midshaft. They change from rursiradiate to prorsiradiate adorally and terminate in concave umbilicolateral bullae. Ribs swing forward in a straight line on the midflanks connecting umbilicolateral bullae to inner ventrolateral tubercles. On the left side, one rib bears two additional bullae, one bulla just dorsal and another just ventral of midflank, and another rib bears a single, weak bulla just dorsal of midflank. The inner ventrolateral tubercles are relatively prominent, given the compressed shape of the shell. On the adapical one­half of the specimen on the right side, these tubercles occur on swollen, concave ribs. The tubercles are evenly spaced at distances of 4.5–5.5 mm at midshaft. They are linked by prorsiradiate swellings to an equal number of outer ventrolateral tubercles, which are also spaced at distances of approximately 5 mm at midshaft; the outer ventrolateral tubercles alternate on either side of the venter. The distance between tubercle rows at midshaft, starting with the umbilicolateral row and including the midflank row, is 3.5 mm, 7.5 mm, and 3.5 mm. The distance between tubercles on either side of the venter is 5 mm.

MICROCONCH DESCRIPTION

AMNH 47305 is the adoral one­half of a body chamber (fig. 40N–P). It is 35.6 mm in maximum length. It is slightly crushed and there is a break through the hook. The whorl section just adoral of midshaft is compressed ovoid with maximum width at the umbilical shoulder in costal and intercostal section. The umbilical wall is flat and inclined outward and the umbilical shoulder is fairly abruptly rounded. The inner and midflanks are very broadly rounded and gently converge toward the venter and the outer flanks (between the inner and outer ventrolateral tubercles) are broadly rounded and converge more steeply toward the venter. The ventrolateral shoulder is fairly abruptly rounded and the venter is broadly rounded.

This specimen is distinguished by the presence of strong ribs on the entire piece of body chamber and the absence of a midflank row of tubercles. Four umbilical tubercles are perched on the umbilical shoulder on the right side and are the most prominent tubercles on the specimen. The distance between umbilical tubercles slightly adoral of midshaft is 6.5 mm. Broad, low ribs arise at or between the tubercles and are prorsiradiate and slightly convex on the flanks. They become more closely spaced, straighter, and more prorsiradiate toward the aperture. The distance between ribs slightly adoral of mid­ shaft is approximately 1 mm. Pairs of ribs loop to the inner ventrolateral tubercles, and at least one rib intercalates at midwhorl height and extends to an outer ventrolateral tubercle. The inner ventrolateral tubercles are less prominent than the umbilical tubercles and are spaced at distances of approximately 4.5 mm slightly adoral of midshaft; because of poor preservation, it is unclear if these tubercles extend to the aperture. The outer ventrolateral tubercles are approximately the same size as the inner ventrolateral tubercles and are spaced at distances of approximately 6 mm slightly adoral of midshaft. The distance between the two rows of tubercles is 3.5 mm. The ventrolateral tubercles are matched on either side of the ventral margin with the distance between them being 8 mm slightly adoral of midshaft. Faint ribs cross the venter with a slight adoral projection.

AMNH 47369 is most of a body chamber of a compressed specimen (fig. 39Q–T). The ratio of whorl width to height at the aperture is 0.95. The flanks are nearly flat and covered with fairly straight prorsiradiate ribs, especially on the hook. The ribs become more closely spaced toward the aperture with intercalation at midwhorl height. Ribs cross the venter with a slight forward projection. The umbilical tubercles are well developed but the midflank tubercles are only represented by bullae. The inner ventrolateral tubercles are of equal size and spacing on the shaft, but abruptly diminish in size and spacing on the hook. The outer ventrolateral tubercles on the shaft are close to the inner ventrolateral tubercles, so that adjacent tubercles are connected by an elongate swelling. The outer ventrolateral tubercles disappear on the hook although this may be due to poor preservation.

DISCUSSION: Among these four specimens, AMNH 47307 (fig. 40J–M) perfectly matches the description of Discoscaphites minardi . In contrast, AMNH 47305 (fig. 40N–P) differs from D. minardi notably in the presence of fairly strong ribs. We provisionally include this specimen in D. minardi .

Discoscaphites minardi closely resembles D. iris , the main differences being that the flanks of the body chamber of D. minardi are flatter and less broadly rounded than those of D. iris , and that the midflank swellings are weak and bullate in D. minardi , if they exist at all, whereas they are sharp and well developed in D. iris .

OCCURRENCE: Upper part of the New Egypt Formation 1.5–2 m below the base of the Hornerstown Formation, and the uppermost 20 cm of the New Egypt Formation and base of the Hornerstown Formation, near Eatontown, northeastern Monmouth County, New Jersey. This species was originally described from the top of the Severn Formation, Betterton quadrangle, Kent County, Maryland ( Landman et al., 2004).

Figures

Fig. 34. Discoscaphites iris (Conrad, 1858). Uppermost New Egypt Formation and basal Hornerstown Formation, AMNH loc. 3345, northwest of Eatontown, Monmouth County, New Jersey. A–D. AMNH 51060, robust macroconch. A, Right lateral; B, apertural; C, ventral; D, left lateral. E–H. MAPS A2060a1, robust macroconch. E, Right lateral; F, apertural; G, ventral; H, left lateral. I, J. MAPS A2060a4, robust microconch with matrix still attached. I, Right lateral; J, ventral. K–M. AMNH 47366, coarsely ornamented macroconch. K, Ventral; L, apertural; M, left lateral. N–P. AMNH 47365, macroconch. N, Right lateral; O, apertural; P, ventral. Q–U. AMNH 47367, macroconch with peel of inner whorls. Q, Right lateral; R, apertural; S, peel of inner whorls; T, ventral; U, left lateral. V, W. AMNH 47372, dimorph indeterminate. V, Right lateral; W, ventral. All figures are X1.

Fig. 35. Discoscaphites iris (Conrad, 1858), macroconchs, cluster 1, uppermost New Egypt Formation, AMNH loc. 3345, northwest of Eatontown, Monmouth County, New Jersey. A–D. AMNH

Fig. 36. A–H, K–Q, S–Z, l–p. Discoscaphites iris (Conrad, 1858), cluster 1, uppermost New Egypt Formation, AMNH loc. 3345, northwest of Eatontown, Monmouth County, New Jersey. A–D. AMNH 47355, macroconch with a repaired injury. A, Right lateral; B, apertural; C, ventral; D, left lateral. E– H. AMNH 47351, macroconch. E, Right lateral; F, apertural; G, ventral; H, left lateral. K–M. AMNH 47347, macroconch. K, Right lateral; L, apertural; M, ventral. N–Q. AMNH 47343, dimorph indeterminate. N, Right lateral; O, apertural; P, ventral; Q, left lateral. S–V. AMNH 47349, dimorph indeterminate. S, Right lateral; T, apertural; U, ventral; V, left lateral. W–Z. AMNH 47339, dimorph indeterminate. W, Right lateral; X, apertural; Y, ventral; Z, left lateral. l–n. AMNH 47336, dimorph indeterminate. l, Apertural; m, ventral; n, left lateral. o, p. AMNH 47332, dimorph indeterminate. o, Right lateral; p, ventral. I, J, R, a–k, q–v. Discoscaphites spp., same loc. as A–H. I, J. AMNH 47350. I, Right lateral; J, apertural; R. AMNH 51063, right lateral. a–d. AMNH 47328. a, Right lateral; b, apertural; c, ventral; d, left lateral. e, f. AMNH 47324. e, Right lateral; f, ventral. g–j. AMNH 47335. g, Right lateral; h, apertural; i, ventral; j, left lateral. k. AMNH 47391, left lateral. q–s. AMNH 47329. q, Right lateral; r, ventral; s, left lateral. t–v. AMNH 47340. t, Right lateral; u, ventral; v, left lateral. All figures are X1.

Fig. 37. A–l. Discoscaphites iris (Conrad, 1858), cluster 1, uppermost New Egypt Formation, AMNH loc. 3345, northwest of Eatontown, Monmouth County, New Jersey. A–D. AMNH 51057, compressed microconch. A, Right lateral; B, apertural; C, ventral; D, left lateral. E–H. AMNH 47354, microconch. E, Right lateral; F, apertural; G, ventral; H, left lateral. I–L. AMNH 51058, microconch. I, Right lateral; J, apertural; K, ventral; L, left lateral. M–P. AMNH 47342, microconch. M, Right lateral; N, apertural; O, ventral; P, left lateral. Q–T. AMNH 47356, microconch. Q, Right lateral; R, apertural; S, ventral; T, left lateral; U–X. AMNH 47352, dimorph indeterminate. U, Right lateral; V, apertural; W, ventral; X, left lateral. Y–b. AMNH 47346, microconch. Y, Right lateral; Z, apertural; a, ventral; b, left lateral. c–f. AMNH 47353, microconch. c, Right lateral; d, apertural; e, ventral; f, left lateral. g, h. AMNH 47345, microconch. g, Right lateral; h, ventral. i–l. AMNH 47337, microconch. i, Right lateral; j, apertural; k, ventral; l, left lateral. m, n. Discoscaphites sp., AMNH 47338, same locality as A–l. m, Right lateral; n, ventral. All figures are X1.

Fig. 38. Discoscaphites iris (Conrad, 1858), microconchs, cluster 2, uppermost New Egypt Formation, AMNH loc. 3345, northwest of Eatontown, Monmouth County, New Jersey. A–D. AMNH 47363. A, Right lateral; B, apertural; C, ventral; D, left lateral. E–H. MAPS A2060a2. E, Right lateral; F, apertural; G, ventral; H, left lateral. I–L. MAPS A2060a3. I, Right lateral; J, apertural; K, ventral; L, left lateral. M–P. AMNH 51055. M, Right lateral; N, apertural; O, ventral; P, left lateral. Q–T. AMNH 47308. Q, Right lateral; R, apertural; S, ventral; T, left lateral. All figures are X1.

Fig. 39. A–P. Discoscaphites iris (Conrad, 1858), uppermost New Egypt Formation and basal Hornerstown Formation, AMNH loc. 3345, northwest of Eatontown, Monmouth County, New Jersey. A– D. AMNH 47105, microconch. A, Right lateral; B, apertural; C, ventral; D, left lateral. E–H. AMNH 51056, microconch. E, Right lateral; F, apertural; G, ventral; H, left lateral. I, J. AMNH 37359, dimorph indeterminate. I, Ventral; J, left lateral. K–M. AMNH 47368, dimorph indeterminate. K, Right lateral; L, ventral; M, left lateral. N–P. AMNH 47105, dimorph indeterminate. N, Right lateral; O, apertural; P, ventral. Q–T. Discoscaphites minardi Landman et al., 2004, AMNH 47369, microconch, same locality as A–P. Q, Right lateral; R, apertural; S, ventral; T, left lateral. U–X, c–f. Discoscaphites spp., same locality as A–P. U–X. AMNH 47371. U, Right lateral; V, apertural; W, ventral; X, left lateral. c– f. AMNH 47374. c, Right lateral; d, apertural; e, ventral; f, left lateral. Y–Z, a, b. Discoscaphites gulosus (Morton, 1834), AMNH 47106, same locality as A–P. Y, Right lateral; Z, apertural; a, ventral; b, left lateral. All figures are X1.

Fig. 41. A–D. Discoscaphites iris (Conrad, 1858), uppermost New Egypt Formation and basal Hornerstown Formation, AMNH loc. 3345, northwest of Eatontown, Monmouth County, New Jersey. A, B. AMNH 47365, a fragment of a macroconch, part of the last suture at a whorl height of approximately 18.2 mm and internal lobe of another suture on the inner whorls. C. AMNH 51060, a macroconch, part of the last suture at a whorl height of 19.7 mm. D. AMNH 51059, a macroconch, part of a composite of two sutures at a whorl height of 7.9 mm. E. Discoscaphites gulosus (Morton, 1834), AMNH 47106, same locality as A–D, part of a composite of two sutures at whorl heights of 17.3 mm and 17.6 mm. F. Discoscaphites sp., AMNH 47107, a fragment, same locality as A–D, part of a suture at a whorl height of approximately 10.3 mm.

Fig. 40. A–D, J–P. Discoscaphites minardi Landman et al., 2004. A–D. MAPS A2059b2, macroconch, upper New Egypt Formation, 1.5–2 m below the base of the Hornerstown Formation, AMNH loc. 3347, northwest of Eatontown, Monmouth County, New Jersey. A, Left lateral; B, apertural; C, ventral; D, left lateral. J–M. AMNH 47307, macroconch, upper New Egypt Formation, 1.5–2 m below the base of the Hornerstown Formation, AMNH loc. 3346, northwest of Eatontown, Monmouth County, New Jersey. J. Right lateral; K, apertural; L, ventral; M, left lateral. N–P. AMNH 47305, microconch, same locality as J–M. N, Right lateral; O, ventral, P, left lateral. E–I, Q–S. Discoscaphites spp., same locality as J–P. E–G. AMNH 47301. E, Right lateral; F, ventral; G, left lateral. H, I. AMNH 47300. H, Right lateral; I, left lateral. Q–S. AMNH 47304. Q, Right lateral; R, ventral; S, left lateral. All specimens are X1.