Collignoniceras Breistroffer, 1947

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 : 41-81

Genus Collignoniceras Breistroffer, 1947

[ICZN, 1968, Opinion 861, name no. 1798; pro Prionotropis Meek, 1876a: 453 , non Fieber, 1853: 127; = Selwynoceras War­ ren and Stelck, 1940: 151; non Collignoniceras Van Hoepen, 1955: 361 ].

TYPE SPECIES: Ammonites woollgari Mantell, 1822: 197 , pl. 21, fig. 16; pl. 22, fig. 7, by the original designation of Meek, 1876a: 453, as type species of Prionotropis Meek, 1876a (non Fieber, 1853) for which Breistroffer (1947, unpaged) proposed Collignoniceras as nomen novum, from the Turonian of England.

DIAGNOSIS: ‘‘Medium­sized, moderately involute to evolute ammonites. Early whorls compressed, parallel­sided, ornamented by crowded or sparse, prorsiradiate, straight or or flared rib, from which commonly arise pairs of low ribs joining siphonal clavi more numerous than the ventrolateral and linked into a more or less continuous keel. Rarely the ornament is greatly reduced on the body whorl. Sutures little incised, with massive saddles’’ (Wright and Kennedy, 1981: 102).

DISCUSSION: See Kennedy et al. (1980: 558) and Wright and Kennedy (1981: 102).

OCCURRENCE: Middle to lower upper Turonian, England, France, Germany, Czech Republic, Poland, Roumania, eastwards to Turkmenistan, Japan, California, northern Mexico, the U.S. and Canadian Interiors, Greenland, North Africa, Colombia, south India, northern Australia. flexuous ribs, mostly long, with weak to strong umbilical bullae. All ribs bear in the early stages outer ventrolateral tubercles in addition to siphonal clavi. This style of ornament is, in some species, retained to maturity. In most, however, the ribs coarsen, become widely spaced, with strong to weak umbilical tubercles (which migrate progressively outward from the umbilical margin), prominent inner and outer ventrolateral tubercles, which may fuse into a massive horn

Collignoniceras woollgari woollgari (Mantell, 1822) Figures 10–15

Ammonites woollgari Mantell, 1822: 197 , pl. 21, fig. 16; pl. 22, fig. 7.

Collignoniceras woolgari (sic) (Mantell) (early form). Merewether et al., 1979: pl. 3, figs. 9, 10.

Collignoniceras woollgari woollgari (Mantell) . Cobban and Hook, 1979: 21, pl. 1, figs. 1–11; pl. 2, figs. 5–22; pl. 4, figs. 11, 12; pl. 5, figs. 13–16; pl. 12, figs. 1, 2 (with synonymy).

Collignoniceras woollgari (Mantell) . Kennedy et al., 1980: 560 (pars), pl. 62; pl. 63, figs. 1–4, 7–12, non 5, 6; pl. 64; pl. 65, figs. 1–3; textfig. 2,?3, 4c, d, non 4a, b.

Collignoniceras woollgari (Mantell, 1822) . Wright and Kennedy, 1981: 103, pl. 28, fig. 3, non 1, 2; pl. 29, fig. 5, non 1–4, 6, 7; pl. 30, fig. 1, non 2, 3.

Collignoniceras woollgari (Mantell, 1822) . Amédro and Badillet, 1982: 131, pl. 5, fig. 1.

Collignoniceras woollgari (Mantell) . Amédro et al., 1982: 30, pl. 1, figs. 5–7.

Collignoniceras woollgari (Mantell) . Amédro and Hancock, 1985: fig. 9e, f.

TABLE 3 Dimensions of Collignoniceras vermilionense (Meek and Hayden, 1860) a

Collignoniceras woollgari woollgari (Mantell) . Cobban, 1986: 81, figs. 6j, k; 7k, l.

Collignoniceras woollgari woollgari (Mantell, 1822) . Kennedy and Cobban, 1988: 604, figs. 7.14, 15.

Collignoniceras woollgari (Mantell, 1822) . Kap­ lan, 1988: 11, pl. 1, fig. 1; pl. 2, figs. 1–7; pl. 7, fig. 1.

Collignoniceras woollgari woollgari (Mantell, 1822) . Kennedy et al., 1989: 86, fig. 24a–c, h–l.

Collignoniceras woollgari (Mantell, 1822) . Cobban and Hook, 1989: fig. 9q, r.

Collignoniceras woollgari (Mantell, 1822) . Amédro, 1990: 269, pl. 24, fig. 2.

Collignoniceras woollgari woollgari (Mantell, 1822) . Emerson et al., 1994: 208, unnumbered figure.

Collignoniceras woollgari woollgari (Mantell, 1822) . Reyment and Kennedy, 2001: fig. 1c, d.

TYPES: Lectotype (fig. 10) is BMNH 5682 , the original of Mantell , 1822: pl. 21, fig. 16, from the Middle Chalk of Lewes , Sussex , England; designated by Wright and Wright, 1951: 35. Presumed paralectotypes (fig. 27E, F) are BMNH C5742 a, b, from the same locality.

DIAGNOSIS: This moderately evolute subspecies has prorsiradiate to rectiradiate primary and secondary ribs that support bullate inner ventrolateral tubercles and clavate out­ er ventrolateral tubercles matched by siphonal clavi.

DISCUSSION: Cobban and Hook (1979) provided an account of C. woollgari woollgari from New Mexico, and Kennedy et al. (1980) and Wright and Kennedy (1981) reviewed the European material at length. We illustrate here a selection of European, Mexican, and U.S. Western Interior material (figs. 10–15) for comparison with C. woollgari regulare , described below, where features distinguishing it from the nominate subspecies are outlined. Gracile and robust forms of C. woollgari woollgari are present, as indicated in the figure captions. Specimens figured by Cobban and Hook (1979) include gracile forms (pl. 1, figs. 1–3, 10, 11; pl. 2, figs. 5– 19; pl. 5, figs. 13–16), and robust forms (pl. 1, figs. 4–9; pl. 2, figs. 20–22; pl. 4, figs. 11, 12; pl. 12, figs. 1, 2).

OCCURRENCE: Collignoniceras woollgari woollgari Subzone , widespread in the U.S. Western Interior from Wyoming to the Rio Grande; California, northern Mexico, Europe, east to Turkmenistan; Tunisia, Japan, and northern Australia.

Collignoniceras woollgari regulare (Haas, 1946) Figures 17–33 , 49L

Prionocyclus (Prionotropis) woolgari (sic) (Mantell). Meek, 1876a: 455, pl. 6, fig. 2; pl. 7, figs. 1, 3.

Prionocyclus (Prionotropis) woolgari (sic) (Mantell). Boyle, 1893: 243.

Prionotropis woolgari (sic) Mantell. Stanton, 1894: 174, pl. 42, figs. 1–4.

Prionotropis woolgari (sic) Mantell. Logan, 1898: 466, pl. 102, figs. 1–4.

Prionotropis woolgari (sic) Mantell. Roman, 1938: 455, pl. 46, fig. 434b, c.

Prionotropis graysonensis (Shumard) . Moreman, 1942: 213 (pars).

Prionotropis woolgari (sic) (Mantell). Shimer and Shrock, 1944: 593, pl. 247, figs. 1, 2.

Prionotropis woollgari (Mantell) and varieties. Haas, 1946: 150, pls. 11, 12; pl. 13, figs. 1–3, 5–18 (non 4, 19); pl. 14, figs. 1–10, 12–16 (non 11); pl. 15, figs. 1–10; pl. 16, figs. 1–21 (non 22–33); non pl. 17; pl. 18, figs. 1, 3–7 (non 8, 9); text­figs. 1–4, 6–14, 19–79, 80–83, 91.

Prionotropis Adkins and Lozo, 1951 : pl. 5, figs. 4–9.

Collignoniceras woollgari (Mantell) . Cobban et al., 1956: 1270, fig. 1b–h.

Collignoniceras woollgari (Mantell) . Matsumoto and Miller, 1958: 353, pl. 44, figs. 1–6; pl. 45, fig. 1.

Collignoniceras woollgari (Mantell) . Matsumoto, 1959: 105, figs. 55–57.

Collignoniceras woollgari (Mantell) . Hattin, 1962: pl. 12, figs. D, E.

Collignoniceras woollgari (Mantell) . Hattin, 1965: fig. 4–3.

Collignoniceras woollgari (Mantell) . Matsumoto, 1965: 11, pl. 1, figs. 1–6; pl. 2, figs. 1–3; pl. 3, figs. 1, 2; text­fig. 6.

Prionocyclus (Collignoniceras) woolgari (sic) (Mantell). Jeletzky, 1970: pl. 26, fig. 9a, b.

Prionocyclus (Prionocyclus) wyomingensis Meek var. robusta Haas. Jeletzky, 1970 : pl. 26, fig. 3.

Prionocyclus (Prionocyclus) wyomingensis Meek var. elegans Haas. Jeletzky, 1970 : pl. 6, fig. 8a, b.

Collignoniceras woollgari (Mantell) . Cobban and Scott, 1972: 94, pl. 14, fig. 5; pl. 30, fig. 1; pl. 37, figs. 9, 10.

TABLE 4 Dimensions of Collignoniceras jorgenseni n. sp. a

Collignoniceras woollgari (Mantell). Hattin, 1975 a: pl. 10, figs. N, P–R.

Collignoniceras woollgari (Mantell). Hattin, 1975 b: pl. 2, figs. 1–3.

Collignoniceras woollgari (Mantell). Cobban, 1976: 120, pl. 1, fig. 7.

Collignoniceras woollgari (Mantell). Kennedy and Cobban, 1976: 46, pl. 10, figs. 1, 2.

Collignoniceras woollgari (Mantell). Kauffman, 1977: pl. 22, figs. 4–6, pl. 26, fig. 6.

Collignoniceras woollgari (Mantell). Hattin, 1977: 189, fig. 8.5.

Collignoniceras woollgari Mantell. Kauffman et al., 1978: pl. 5, figs. 4–6.

Collignoniceras woollgari (Mantell). Hattin and Siemers, 1978: figs. 7.10, 10.5.

Collignoniceras woollgari (Mantell) (late form). Merewether et al., 1979: pl. 3, figs. 4, 5.

Collignoniceras woollgari regulare (Haas). Cobban and Hook, 1979: 22, pl. 3, figs. 1–14; pl. 12, fig. 3.

Collignoniceras woollgari (Mantell). Kennedy et al., 1980: 560 (pars), pl. 63, figs. 5, 6; pl. 65, figs. 4–8.

Collignoniceras woollgari (Mantell, 1822). Wright and Kennedy, 1981: 103 (pars), pl. 28, fig. 2; pl. 29, figs. 2, 6, 7; pl. 30, fig. 3.

Collignoniceras woollgari regulare (Haas). Cobban, 1983: 16, pl. 15, figs. 2– 4, 7–11.

Collignoniceras woollgari regulare (Haas). Cobban, 1984 b: 14, pl. 2, figs. 6, 7.

Collignoniceras woollgari (Mantell). Kennedy, 1986: pl. 13, figs. 1–3.

Collignoniceras woollgari (Mantell). Wright and Kennedy, 1987: 166, pl. 34, figs. 5, 6.

Collignoniceras woollgari regulare (Haas). Kennedy, 1988: 74, pl. 14, figs. 1, 2, 4, 5, 10, 11.

Collignoniceras woollgari regulare (Haas). Kennedy and Cobban, 1988: 606, figs. 7.9–7.15.

Collignoniceras woollgari (Mantell, 1822) regulare (Haas, 1946). Kennedy et al., 1989: 88, figs. 21, 22, 23, 24 d.

Collignoniceras woollgari (Mantell). Kennedy, 1989: 257, fig. 7.

Collignoniceras woollgari (Mantell). Cobban, 1990: B9, pl. 5, figs. 6–13.

Collignoniceras woollgari regulare (Haas, 1946). Emerson et al., 1994: 209, 378.

Collignoniceras woollgari regulare (Haas, 1946). Reyment and Kennedy, 2001: fig. 1e–j.

TYPES: Holotype, by original designation, South Dakota State School of Mines Collection no. 1470, the original of Haas, 1946, plate 16, figures 14, 16; text­figs. 80, 81, from an unknown horizon and locality in the Black Hills area (fide Haas, 1946: 198).

MATERIAL: The present description is based on more than 500 specimens from USGS Mesozoic locality 21792, limestone concretions 18.9–21.3 m above the base of the Carlile Shale, middle Turonian Collignoniceras woollgari Zone , regulare Subzone, 1.6 km west of Newcastle in the NW ¼ sec. 31, T. 45 N, R. 61 W, Weston County, Wyoming, and from USGS Mesozoic locality D9896, limestone concretions about 18.3 m below the Turner Sandy Member of the Carlile Shale, middle Turonian Collignoniceras woollgari Zone , regulare Subzone, NW ¼ sec. 35, T. 46 N, R. 63 W, Weston County, Wyoming. We have several hundred

498260; G–I. USNM 498262; J, K. USNM 498259; L, M. USNM 498269; N, O. USNM 498270; P,

additional specimens from many localities in South Dakota, Wyoming, Colorado, Utah, and New Mexico.

DIAGNOSIS: A moderately evolute subspecies that usually has prorsiradiate single ribs that support umbilical and inner and outer ventrolateral tubercles matched by prominent siphonal clavi.

DESCRIPTION: Nuclei are highly variable (figs. 17, 21). At one extreme are compressed, high­whorled individuals of the gracile form (fig. 17A–C, J, K, O–Q, T, U, X, Y) with costal whorl breadth to height ratios of as little as 0.51 and an umbilical to shell diameter ratio of 0.29 (table 2). The umbilicus is broad, with a low umbilical wall, and a broadly rounded umbilical shoulder. The flanks are flattened and subparallel with the ventrolateral shoulders rounded. At diameters up to a maximum of 27 mm, there are dense, crowded ribs that total as many as 70 per whorl. They arise singly or in pairs at the umbilical shoulder or intercalate, arising at various levels just outside the umbilical shoulder and well below midflank. The ribs are straight, narrow and rounded, and prorsiradiate to the ventrolateral shoulder, where they flex forward; they are concave over the shoulder and project forward to the siphonal keel, producing an acute chevron. Small outer ventrolateral clavi are present from the earliest ornamented stage, and are separated by a ventral groove from the siphonal keel, which bears small clavi, equal in number to but displaced slightly aperturally of the outer ventrolateral clavi. Weaker inner ventrolateral clavi appear after the outer ones, and may be absent to a diameter of as much as 12 mm.

At the other extreme are more robust nuclei (fig. 21C, D, J–L) with whorl breadth to height ratios of up to 0.95 and an umbilical to shell diameter ratio of up to 0.40 (table 2). These have as few as 24 ribs per whorl, all of which are coarse, blunt, straight and prorsiradiate. The ribs bear weak umbilical bullae and prominent conical inner ventrolateral and clavate outer ventrolateral tubercles from an early stage. The siphonal keel is coarse.

There is every intermediate between these two forms in terms of rib density, and great variation in the diameter to which the simply ornamented stage persists. Thus, at a diameter of as little as 7 mm (fig. 21M–O) to a diameter of up to 27 mm there is a marked change in rib density; compressed gracile individuals may have as few as 17 or 18 ribs per whorl at diameters of 20–35 mm (fig. 21X–Z), decreasing to as few as 11 by a diameter of 75 mm (fig. 21U–W). The coiling in these gracile specimens is very evolute, with U/D up to 0.38 and intercostal whorl breadth to height ratios of as little as 0.57 (table 2). The umbilicus is very shallow, with a low umbilical wall, and rounded umbilical shoulder. The flanks are flattened and subparallel in intercostal section with rounded ventrolateral shoulders, and a high, sharp keel. The ribs are very narrow, and the interspaces between them become progressively wider as the diameter increases. At small diameters, the ribs originate at umbilical bullae, but with increasing diameter, the ribs become very high and flared, reaching their maximum elevation across the flanks. The ribs are markedly prorsiradiate, straight, and feebly concave across the flanks, and each rib bears a strong conical inner ventrolateral tubercle and a strong clavate outer ventrolateral tubercle. The two tubercles progressively assimilate into a flared ventrolateral rib that sweeps forward over the ventrolateral shoulder before weakening abruptly prior to meeting the siphonal keel. The keel is high and crenulate, with long, high, siphonal clavi that are markedly asymmetric in profile (fig. 23A–E). Fine lirae are developed, or not, on the interspaces between ribs (fig. 23), but do not bear any tubercles. There are an equal number of umbilical bullae, inner and outer ventrolateral, and siphonal tubercles. The largest individual of the gracile type from the Carlile Shale concretions has a diameter of 105 mm; fragments have whorl heights of up to 150 mm.

Q. USNM 498264; R, S. USNM 498261; T. USNM 498271; U–W. USNM 498265; all from locality 15. X–Z. USNM 498272 from locality 12. All figures are ×1.

Robust variants show a comparable change in ribbing density at variable diameters. At diameters of up to 75 mm, these specimens have umbilical to shell diameter ratios of up to 0.34 and a quadrate whorl section. Ribs number as few as 14 per whorl with strong, persistent umbilical bullae. Ribs are blunt, low, coarse, and prorsiradiate, and bear large, conical inner ventrolateral tubercles that are connected by broad prorsiradiate ribs to strong, outer ventrolateral clavi. The siphonal keel is coarse with clavi that correspond in number to that of the outer ventrolateral clavi. The largest observed individual of the robust type is USNM 252804, 145 mm in diameter (Cobban and Hook, 1979; pl. 3, figs. 13, 14). Other fragments are still septate at 65 mm whorl height.

The collections also contain fragments of body chambers that show distant ribs with bullae that have migrated out to an inner flank position, and enlargement of the inner ventrolateral tubercles into long, finger­like horns (fig. 20B–D), into which the outer ventrolateral clavi are progressively assimilated. The mature body chamber morphology of the gracile form is best shown by specimens from the Chispa Summit Formation at Chispa Summit in Jeff Davis County, Trans­Pecos Texas. Here, compressed adult body chambers (Kennedy et al., 1989: fig. 23) that overlap in size and ornament with the similarly compressed juveniles from the Carlile Shale of Wyoming already described reach diameters of up to 200 mm. The intercostal whorl section is compressed oval. Distant ribs bear flared umbilical bullae, which progressively migrate out from the umbilical shoulder; each ventrolateral horn is linked by a high rib to a siphonal clavus. The costal whorl section is markedly fastigiate and a low siphonal ridge links the clavi. The final portion of the body chamber before the adult aperture is smooth and tubular without major ribs, but sometimes bears nontuberculate lir­ ae. We tentatively interpret these forms as adult microconchs.

Much larger body chambers (figs. 24, 25) belong to the robust form. A South Dakota example is shown in fig. 25; at Chispa Summit, such specimens (fig. 24) are up to 360 mm in diameter. These correspond to the robust juveniles in the South Dakota fauna and we tentatively interpret them as macroconchs. In some there is a long, low siphonal clavus corresponding to each ventrolateral horn, successive clavi being linked by a siphonal ridge. Low riblets arise from the adapical and adapertural terminations of each ventrolateral horn and loop to the siphonal clavus. In others, small siphonal clavi may be present in the interspaces between larger ones.

European specimens referred to C. woollgari regulare (figs. 26–32) reach comparable sizes and show the same ontogenetic changes as the U.S. material described here.

Sutures moderately incised with broad, bifid E/L, narrower L, and L/U 2 broader than U 2 (fig. 33). Several sutures were illustrated by Meek (1876a: pl. 7, fig. 1e, h) and Matsumoto (1965: fig. 6A, D, F).

DISCUSSION: Gracile microconchs and robust macroconchs can be recognized from an early ontogenetic stage; the former dominate the Black Hills assemblages upon which the above description is largely based. Haas (1946) analyzed variation in C. woollgari , in large part on the basis of 325 specimens from a single concretion he believed to have been collected by the Powell Survey from southern Utah. We have never seen such concretion preservation from Utah and suspect rath­ er that the material is from the Black Hills. Haas’s Forma typica (1946: pl. 13, figs. 1, 4–19; text­figs. 3–5, 25–29, 31–38) are macroconch fragments; the original of his plate 14, figure 11, seems to be a crushed Plesiacanthoceras wyomingense Reagan, 1924 . Variety regularis, the name selected for the late subspecies of woollgari (Haas, 1946: 154, pl. 16, figs. 1–17; text­figs. 10–12, 59–74, 78, 80, 81, 83), is based on gracile juvenile microconchs. Variety crassa (Haas, 1946: 153, pl. 14, figs. 1, 5; pl. 15, figs. 7, 8; text­figs. 6, 39) is based on evolute, robust, juvenile microconchs. Variety intermedia (Haas: 1946: 154, pl. 14, figs. 2–4, 6–10, 12–16; pl. 15, figs. 1–6, 9, 10; text­figs. 7–9, 40–44, 46–58) and variety tenuicostata (Haas, 1946: 155, pl. 16, figs. 18–21; text­figs. 13, 14, 75– 77, 82) are based on juvenile microconchs.

C. woollgari var. praecox of Haas (1946: 155, pl. 16; figs. 2–33: pl. 17, figs. 1–5; pl. 18, figs. 1, 8, 9; text­figs. 15–18, 79, 84–90)

498282, all from locality 15. X, Y. USNM 498283, from locality 12. Z–B 1. USNM 498284 from locality 19. All figures are X1.

is based on specimens from USGS localities 12642 and 18872 in the Black Hills of South Dakota, and Haas specifically noted that the variety is unknown from any other locality in the Black Hills area or in the block from ‘‘southern Utah’’ that yielded specimens of his other varieties. As already noted, subsequent collecting shows that this form, here regarded as a fully separate species ( C. praecox ), is younger than C. woollgari regulare . Collignoniceras praecox differs in the marked differentiation of ribs into strong and bullate and weak and nonbullate in the earliest stages of development, persistence of differentiated ribbing through middle growth, and the development in the adult of inner ventrolateral bullae or spines on distant primary ribs, many ventrolateral riblets, and an entire or minutely crenulate keel.

Matsumoto (1965: 11) also analyzed variation in juvenile Collignoniceras woollgari regulare from a collection made from 10 m above the base of the Carlile Shale 3.2 mi southwest of Newcastle, Wyoming. His groups A through D and F are probably all juvenile microconchs, his group E, juvenile macroconchs.

Collignoniceras woollgari regulare differs from the nominate subspecies in that in mid­ dle and later phragmocone whorls of the latter, there are more siphonal tubercles than ventrolateral ones, and looped ribs connect opposite ventrolateral horns. This generally also separates body chambers, but multiple siphonal tubercles sometimes appear on adult body chambers of C. woollgari regulare , as do looped ribs.

Collignoniceras vermilionense (Meek and Hayden, 1860) (see below) is a much smaller species, showing comparable dimorphism to that of C. woollgari regulare . Inner whorls are coarsely ribbed. In the microconch, which is adult at 55 mm diameter, coiling is very evolute. There are only outer ventrolateral clavi whereas in C. woollgari regulare of this size, there are both inner and outer ventrolateral clavi.

OCCURRENCE: Widely distributed in the Western Interior of the United States from northern Montana south to Trans­Pecos Texas, and from central Utah east to western Iowa. It is also found in northeastern Texas as well as California and Oregon. The subspecies also occurs in Canada (Manitoba), northern Mexico (Chihuahua), southern England (figs. 27A–G) and France (figs. 26, 28–32).

Collignoniceras vermilionense (Meek and Hayden, 1860) Figures 34D–H , 35A , 37 (pars)

Ammonites vermilionensis Meek and Hayden, 1860: 177 .

Mortoniceras ? vermilionense (Meek and Hayden) . Meek, 1876a: 450, pl. 7, fig. 2.

TABLE 5 Dimensions of Collignoniceras praecox (Haas, 1946) a

Mortoniceras vermilionense (Meek and Hayden) . Stanton, 1894: 180, pl. 44, fig. 1.

Mortoniceras vermilionense (Meek and Hayden) . Logan, 1898: 472, pl. 104, fig. 1.

Prionotropis vermilionensis (Meek and Hayden) . Reeside, 1927: 10.

Collignoniceras vermilionense (Meek and Hayden) . Cobban, 1983: 17, pl. 5, figs. 38–40 (non 41, 42, = C. praecox ).

[ Collignoniceras vermilionense ]. Ludvigson et al., 1994: fig. 7a.

TYPE: Holotype by monotypy is USNM 224 (fig. 34D, E), from a limestone concretion in the Carlile Shale, inferred to be the middle Turonian Collignoniceras praecox Zone , on the Missouri River opposite the mouth of the Vermillion (formerly Vermilion) River in Dixon County, Nebraska.

DIAGNOSIS: A fairly small, keeled, evolute species that has closely spaced primary and secondary ribs on the innermost whorls, but mostly widely spaced, single, prorsiradiate ribs on later whorls. Ribs arise from low umbilical bullae and terminate in arcuate ventrolateral swellings that may or may not support inner ventrolateral tubercles and faint outer ventrolateral clavi. Keel is moderately high and strengthened into asymmetric clavi corresponding to the ribs.

DESCRIPTION: The holotype is a juvenile. Coiling is very evolute, with U/D = 0.44– 0.46 (table 3). The umbilicus is shallow, with a low, flattened wall and broadly rounded shoulder. The flanks are flattened. There are 26 primary ribs per whorl visible at a diameter of approximately 15 mm. All arise at the umbilical seam and strengthen across the umbilical shoulder. At the smallest observed diameter, there is a slight differentiation into stronger ribs with umbilical bullae separated by somewhat weaker ribs with weak or no bullae, but this differentiation declines and disappears with increasing size, and the ribs coarsen progressively. All ribs are blunt and recti­ to feebly prorsiradiate on the flanks. Each rib strengthens into an inner ventrolateral bulla from which the rib projects strongly forward, declining markedly in strength and bearing a weak outer ventrolateral clavus.

USNM 299166 (Cobban, 1983: pl. 5, figs. 39, 40; fig. 34F, G), 56.0 mm in diameter, with inner whorls that are essentially identical to those of the holotype shows the succeeding ontogenetic stages. Coiling is very evolute, with U/D = 0.46 (table 3); the umbilicus is shallow, with a low wall. The intercostal whorl section is very compressed, with a whorl breadth to height ratio of 0.63, the greatest breadth just outside the umbilical shoulder. The costal ratio is 0.76, the greatest breadth at the umbilical bulla. The inner whorls are densely and evenly ribbed with 12 primary ribs per half whorl. There are a total of 18 ribs on the outer whorl, all bullate primaries. They are narrow, very distant, prorsi­ radiate to the ventrolateral shoulder, where each bears a pronounced bullate ventrolateral tubercle at the smallest diameter visible, but which thereafter declines and effaces, leaving a weakening rib that sweeps forward and is markedly concave over the ventrolateral shoulder. There is a high siphonal keel with long siphonal clavi, corresponding in number to, but displaced adaperturally of, the ventrolateral clavi or their site. The umbilical bullae decline markedly towards the aperture, suggesting that this specimen may be close to maturity.

A magnificent specimen from a limestone concretion from the Carlile Shale near Yankton, South Dakota, in the S. D. Jorgensen collection (Co1970A: fig. 34H, table 3) has one side preserved. This specimen, 83.8 mm in diameter, has a body chamber occupying the last one­half whorl and terminating in a pronounced rostrum 35 mm long. At the smallest diameter visible, approximately 7.5 mm, ribs are single and of equal height. All ribs at larger diameters are primary, narrow, and prorsiradiate. They number 32 per whorl at a diameter of about 11 mm, 26 per whorl at about 19 mm diameter, and 24 per whorl at 83 mm diameter. All arise from low, inconspicuous bullae on the narrowly rounded umbilical shoulder, incline forward on crossing the flank, rise into low bullae on the ventrolateral shoulder, and then bend forward sharply and disappear close to the keel. Bullae are reduced in size

TABLE 6 Dimensions of Collignonicerites collisniger n. gen., n. sp. a

near the aperture, and the last two septa are approximated.

The suture, illustrated by Meek (1876a: pl. 7, fig. 2b), is fairly simple and proportioned like that of the juvenile Collignoniceras woollgari figured by Meek (1876a: pl. 7, fig. 1e). Part of a suture near the aperture of the large Jorgensen specimen is shown in fig. 35A.

DISCUSSION: This is a very rare species. Cobban (1983) initially considered it Collignoniceras praecox (Haas, 1946) . The latter, however, has straight, rectiradiate ribs that terminate in sharp horns in contrast to the prorsiradiate ribs of C. vermilionense that bear fowardly inclined ventrolateral bullae.

OCCURRENCE: Known only from the Carlile Shale in northeastern Nebraska and southeastern and southwestern South Dakota; Collignoniceras praecox Zone.

Collignoniceras jorgenseni , new species Figures 34A–C , 35B , 36 , 37 (pars), 38 (pars)

DERIVATION OF NAME: For Steven D. Jorgensen of Omaha, Nebraska, who donated the holotype and several other specimens from his extensive collections of Cretaceous ammonites.

TYPES: Holotype is USNM 498249 (fig. 36A) from the Collignoniceras praecox Zone in the middle Turonian Carlile Shale at USGS Mesozoic locality D 13834 in the SW1/4 SW1/4 sec. 25, T. 7 S, R. 6 E, Fall River County, South Dakota. Paratypes USNM 498253 (figs. 35B, 36B–D, K) 498254 (fig. 36H–J), 498251, and 498252 are from the same locality. Paratype USNM 498250 (fig. 34A–C) is from the Carlile Shale at USGS Mesozoic locality D12683 (locality 13 in fig. 1) in the NE1/4 NW1/4 sec. 32, T. 94 N, R. 50 W, Union County, South Dakota.

DIAGNOSIS: A rather small, evolute species that has prorsiradiate primary and secondary ribs throughout. Primary ribs bear umbilical bullae and inner and outer ventrolateral tubercles. Keel supports a clavate tubercle for each rib. Primary ribs are commonly flared.

DESCRIPTION: The holotype (fig. 36A) is a small adult, 38.3 mm in diameter, embedded in part of a limestone concretion, so that only one side is visible. Slightly more than one half of the last whorl is body chamber, followed by a long rostrum. The umbilicus is shallow with U/D = 0.42 (table 4). The umbilical shoulder is narrowly rounded. Whorls are apparently higher than wide, are somewhat flattened, and have a narrowly rounded ventrolateral shoulder. The keel is fairly high and accentuated into clavi that correspond to the ribs. Those clavi corresponding to the secondary ribs are low and symmetric; those corresponding to the primary ribs are high and asymmetric with the steep slope forward.

Ornament of the holotype consists of prorsiradiate ribs of unequal heights and umbilical and ventrolateral tubercles as well as siphonal clavi. All ribs are narrow, and all arise on the umbilical shoulder. Primary ribs arise from narrow, umbilical bullae or from narrow, bullate tubercles. Each primary is inclined forward on crossing the flank and then rises into a prominent, arcuate ventrolateral swelling that supports a weak inner ventrolateral tubercle and a weaker outer ventrolat­

USNM 498299 ; K. paratype USNM 498300 ; M, R–T. holotype, USNM 498294 ; N. O–Q. paratype USNM 498302 . L. Collignoniceras woollgari regulare (Haas, 1946) , robust form. All specimens are from locality 12. Figures A–L, O–T are X2 ; figures M, N are X1.

eral tubercle before diminishing and disappearing at an acute angle to the keel. Some primaries are flared. There are 12 primaries on the outer whorl. Each pair of primary ribs is separated by one to four low, narrow, secondary ribs that are usually accentuated on the ventrolateral shoulder, but do not bear tubercles. Total primary and secondary rib counts per whorl are as follows: 35 at a diameter of approximately 6 mm, 38 at a diameter of about 14 mm, and 38 at a diameter of about 22.5 mm.

That the holotype is a small adult is revealed by the weakening and disappearance of tubercles on the last part of the body chamber, and by the presence of a long (13.5 mm) rostrum. Only short sections of the suture are visible.

Two paratypes (fig. 36B–D, K and 36H– J) from the same concretion as that of the holotype (fig. 36A) are adults 61 and 65 mm in diameter with umbilical to shell diameter ratios of 0.38 and 0.45, respectively. Both have crushed body chambers with the rostra broken off; the phragmocones are slender and probably somewhat crushed. Ribbing is sparser than that of the holotype, and primaries and secondaries alternate. Another adult paratype (unfigured) from the same concretion has a diameter of 50.5 mm and an umbilical to shell diameter ratio of 0.48. Its body chamber is also crushed, but the prominent rostrum is preserved. Most primary ribs are separated by two secondaries.

The holotype (fig. 36A) and paratypes USNM 498250 (fig. 34A–C) and 498252 represent the robust form of the species. Paratypes USNM 498253 (fig. 36B–D, K) and 498254 (figs. 36H–J) represent the gracile form.

A complete suture is not visible on any specimen. The lateral lobe and adjoining saddles on one of the paratypes is shown in fig. 35B.

DISCUSSION: Collignoniceras jorgenseni resembles C. vermilionense in size, in its wide umbilicus, and in its conspicuous prorsiradiate ribbing, but C. jorgenseni differs in its dense ribbing and abundant secondaries. Both forms occur with C. praecox and C. percarinatum .

OCCURRENCE: Known only from the lower part of the Carlile Shale in the Black Hills area of western South Dakota, Collignoniceras praecox Zone.

Collignoniceras praecox (Haas, 1946) Figures 39–47

Prionotropis woollgari Meek (non Mantell) var. praecox Haas, 1946: 155 , pl. 16, figs. 22, 23; pl. 17, figs. 1–5; pl. 18, figs. 1, 8, 9; text­figs. 15–18, 79, 84–90.

Collignoniceras vermilionense (Meek and Hayden) . Cobban, 1983: 17 (pars), pl. 5, figs. 41, 42.

Subprionocyclus percarinatus (Hall and Meek) . Cobban, 1983: 18 (pars), pl. 5, figs. 26–29, 32, 33, 36, 37.

Collignoniceras praecox (Haas, 1946) . Reyment and Kennedy, 2001: fig. 1 k–n.

TYPES: Holotype is USNM 318219 (fig. 40D, E) (formerly 103913), paratypes USNM 103913 a–e (fig. 40F–I; USNM 103913 C not figured), all from the Carlile Shale, middle Turonian Collignoniceras praecox Zone at USGS Mesozoic locality 18872, 3.2 km southeast of Fairburn , Custer County, South Dakota.

DIAGNOSIS: Moderate to fairly large species with highly variable juvenile whorls that range from densely ribbed with distinct primaries and secondaries to more evenly and sparsly ribbed. Adults have sparser and usually weaker ribs and prominent ventrolateral horns.

DESCRIPTION: The present collections are nearly all juveniles of the gracile form. Coiling is fairly evolute, with an umbilicus to shell diameter ratio of just under 0.30 (table 5). The whorl section is compressed oval in intercostal section and polygonal in costal section with whorl breadth to height ratios of as little as 0.62. Ribbing is highly variable at small diameters (figs. 39, 40A–C, R–H; 41A–W), but generally shows a marked differentiation into strong and weak primary ribs and weak intercalaries that give these small specimens a highly distinctive appearance. There are up to 10 flared primary ribs per whorl with well­developed umbilical bullae. The primary ribs are narrow, high, and prorsiradiate on the flanks, and each bears a well­developed feebly clavate inner ventrolateral tubercle from which the rib projects sharply forward to a clavate outer ventrolateral tubercle. Between the flared primary ribs are up to four much weaker, nonbullate ribs without ventrolateral tubercles. These specimens closely match one of the paratypes (USNM 103913b, Haas, 1946: pl. 16, fig. 29, cast refigured here as fig. 40H), which shows similar ornament to a whorl height of 14 mm, at which point each weaker rib bears a feeble inner ventrolateral tubercle with pairs of both inner and outer ventrolateral tubercles present on the stronger ribs. Beyond this whorl height, the weaker ribs efface markedly, leaving primary ribs and lirae on the flanks (USNM 498283, fig. 41X, Y). In other specimens (fig. 39G–K) this stage of markedly differentiated ribs is followed, to a diameter of at least 35 mm, by a stage with crowded, dense bullate and nonbullate primary and occasional intercalated ribs that total up to 55 per whorl. These specimens are very similar to paratype USNM 103913d (Haas, 1946: pl. 18, figs. 8, 9; fig. 40F); the ribs are straight and prorsiradiate, and are separated by narrow interspaces. Each rib bears a bullate inner ventrolateral tubercle from which the rib projects abruptly forward and links to a clavate outer ventrolateral tubercle. All these variants have a pronounced siphonal keel with numerous siphonal clavi that are either as numerous or fewer in number per whorl than the ventrolateral tubercles. In middle growth there is an abrupt change to widely spaced ribs (figs. 39X–Z; 40D, E, I; 41X, Y). Bullate primaries alternate with nonbullate long and short ribs, all with conical inner and clavate outer ventrolateral tubercles, the compressed whorl section and feeble flank ornament being distinctive at this size; the holotype is just such a specimen (fig. 40D, E). In ventral view these specimens show the ribs extending in attenuated form forward to intersect the line of the keel at an acute angle, with the interspaces between ribs covered in growth striae, lirae, and riblets. At this stage, the crenulations on the keel are very sub­ dued. In some there are merely irregular elevations; in others (e.g., Haas, 1946: pl. 17, fig. 4; fig. 40I) the keel is almost entire. Our largest specimen of this kind, USNM 498267 (fig. 42), shows progressive effacement of flank ornament and the coalescence of inner and outer ventrolateral tubercles into blunt inner ventrolateral horns. USNM 498284 (fig. 41Z–B̍) shows the same transition at only 60 mm diameter.

Juveniles of the robust form are evolute with U/D up to 0.35 (fig. 43E, F; table 5). Their innermost whorls may or may not show differentiation into strong, bullate and weaker, nonbullate ribs. In middle growth, the few available specimens have strong, distant primary ribs with bullae and inner and outer ventrolateral tubercles differentiated to whorl heights of up to 30 mm, with shorter, weaker ribs between. Adults (figs. 44–46) have sparse primary ribs ending in pronounced ventrolateral tubercles or horns.

Several sutures were shown by Haas (1946: figs. 79, 84–90); that of one of the paratypes ( USNM 103913 e) is reproduced here (fig. 47) .

DISCUSSION: Haas (1946: 156) rightly remarked on the distinctive features of this species: ‘‘the accelerated development of this variety from maturity to the latest ontogenetic stage has been alluded to in its name. The differentiation between stronger and weaker ribs and the later disappearance of those of the latter kind cause this variety, of all of the various forms of P. woollgari , most to resemble the genus Prionocyclus . Furthermore it is the only form of, or close to P. woollgari here dealt with that might perhaps be granted the status of an independant species.’’ Collignoniceras praecox thus

TABLE 7 Dimensions of Prionocyclus hyatti (Stanton, 1894) a

nile C. woollgari woollgari and C. praecox , but the strong siphonal clavi of the former, corresponding to the outer ventrolateral tubercles in number, separates them; adults are very different.

OCCURRENCE: Known with certainty only from the lower part of the middle Turonian Carlile Shale of South Dakota, Collignoniceras praecox Zone.

differs from C. woollgari regulare in the middle growth stages by the persistence of long and short ribs, with ventrolateral tubercles outnumbering umbilicals. The presence of a near continuous keel where C. woollgari regulare has clavi equal in number to the ventrolateral tubercles is also distinctive. Adult C. woollgari are much larger than those of C. praecox , and have a highly distinctive ribbing and ventral ornament. There are closer similarities between juve­

Collignoniceras percarinatum (Hall and Meek, 1856)

Figure 48

Ammonites percarinatus Hall and Meek, 1856: 396 , pl. 4, fig. 2a, b.

Prionotropis woolgari (sic) Mantell (sp.). Stanton, 1894: 174.

Ammonites percarinatus Hall and Meek. Diener, 1925: 32 .

Prionotropis percarinatus (Hall and Meek) . Haas, 1946: 150, 158.

Collignoniceras woollgari (Mantell) . Stephenson, 1953: pl. 12, fig. 3.

Subprionocyclus percarinatus (Hall and Meek) . Cobban, 1983: 18, pl. 5, figs. 30, 31, 34, 35 (non figs. 26–29, 32, 33, 36, 37 (= Collignoniceras praecox )); pl. 15, figs. 5, 6.

Prionocyclus percarinatus (Hall and Meek) . Cobban, 1984a: 75, 84.

non Prionocyclus percarinatus ( Hall and Meek, 1856) . Kirkland, 1996: 99, pl. 40, figs. B–F, I. TYPES: Lectotype AMNH 31995 (fig. 48J), designated by Cobban (1983: 18), and paratypes are from ‘‘ Five miles below the mouth of Vermilion River on the Missouri’ ’ (Hall and Meek, 1856: 396). As noted by Cobban (1983: 18), the specimens came from rocks now assigned to the middle Turonian Carlile Shale , probably from the northeast side of Volcano Hill in sec. 3, T. 31 N, R. 5 E, Dixon County, Nebraska.

DIAGNOSIS: A small species that has closely spaced, prorsiradiate ribs of rather uniform height. Ribs bend forward at the ventrolateral shoulder and fade out at the low keel. Keel notched by low clavi that correspond in number to the ribs.

DESCRIPTION: Hall and Meek’s description is as follows: ‘‘Discoidal, depressed; umbilicus wide and shallow; volutions about four or five, all visible in the umbilicus, scarcely one fourth of each embraced in the succeeding one; shell thin; surface marked by thirty­eight to forty­five prominent flexuous sharp ribs some of which originate in the umbilicus, and others upon the lateroventral margin, and all extend to the dorsolateral edge, where they bend abruptly forward, and terminate before reaching the dorsal line, which is marked by a thin sharp carina extending to the aperture. Ribs thickened and sometimes nodose towards the periphery. Our specimens are all casts of the interior with fragments of the shell adhering, and the condition is such as to give no means of determining the character of the septa.’’

A suite of small specimens from limestone concretions in the lower part of the Carlile Shale at locality 15 in figure 1, USGS Mesozoic locality D10697, in Fall River Coun­ ty, South Dakota, seem assignable to this species (fig. 48A–H, K–P). The specimens are fairly evolute with umbilical to shell diameter ratios of 0.33–0.48 and 32–38 ribs on the outer whorl. Ribs are prorsiradiate, arise at the umbilicus, cross the flank, and curve forward at the ventrolateral shoulder, where they are accentuated a little or actually form low clavate tubercles. The low keel bears asymmetrical clavi that have the steeper slope on the adoral side. Each siphonal clavus matches a rib.

DISCUSSION: The presence of a siphonal clavus for each rib supports the assignment to Collignoniceras rather than to Prionocyclus . In later whorls, the species resembles C. vermilionense in having single prorsiradiate ribs that bend forwards sharply on the ventrolateral shoulder. The latter species, however, is much more coarsely ribbed and has larger, more pronounced siphonal clavi.

OCCURRENCE: Known only from the middle Turonian Carlile Shale, Collignoniceras praecox Zone , of southeastern South Dakota, northeastern Nebraska, and western Minnesota. Specimens figured as Prionocyclus percarinatus by Kirkland (1996: 99, pl. 40, figs. B–F, I) from the Collignoniceras woollgari regulare Subzone in the Mancos Shale of northeastern Arizona have differentiated ribs to a much larger size than on C. percarinatus and represent some other species. Likewise, specimens recorded as Subprionocyclus percarinatus ? from the Mancos Shale of westcentral New Mexico by Hook et al. (1983: sheet 1) also belong to some other species.

Genus Collignonicerites , new genus

DERIVATION OF NAME: Collignoniceras plus ites (Latin)—descendant of Collignoniceras .

TYPE SPECIES: Collignonicerites collisniger n. gen., n. sp.

DIAGNOSIS: Small, adult at 18 mm or less, involute with compressed whorl section. Distant, blunt umbilical bullae give rise to pairs or groups of ribs, with one or several nonbullate long ribs between; ribs blunt, crowded, prorsiradiate, flexuous, all with small outer ventrolateral clavi. Venter broad, flat, with strong siphonal keel and weak siphonal clavi equal in number to ventrolateral clavi but displaced adaperturally on phragmocone. Ornament declines on adult body chamber, which may be constricted; umbilical bullae present, flank ribs decline but ventrolateral ornament persists; siphonal clavi become irregular.

The suture is very simple with broad bifid E/L with few incisions, narrower L, and nearly entire L/U 2.

DISCUSSION: Decline in ornament and the development of constrictions indicates that the species attains maturity at 17 mm or less, while the very simple adult suture indicates that these specimens are more than mere juveniles of some larger form. Collignonicerites resembles Collignoniceras ; the very simple suture of Collignoniceras (e.g., Matsumoto, 1965: text­fig. 6A) is retained to maturity in Collignonicerites . The phragmocone ornament of Collignonicerites with outer ventrolateral clavi equal in number to siphonal clavi and ribs springing in groups from bullae resembles that of the ornamented earliest developmental stages of Collignoniceras with which Collignonicerites collisniger gen. et sp. nov. co­occurs.

Collignonicerites is an analog of Prionocyclites Kennedy, 1988 , a diminitive genus closely related to Prionocyclus . Species of the two genera share certain features common to progenetic dwarfs, including a greatly simplified suture. However, they differ in that species of Prionocyclites are more evo­ lute and lack massive bullae giving rise to groups of ribs, having instead narrow, distant, single bullate primaries separated by nonbullate primaries and secondaries, an undulose rather than serrated keel, and a body chamber with distant feeble bullae, narrow, single flank ribs, and an apertural constriction flanked by collar­ribs.

Progenetic species have increasingly been described in recent publications on Late Cretaceous ammonites, as noted by Wright (1996: xviii; see, for instance, Wright and Kennedy, 1980; Kennedy, 1988; Kennedy and Cobban, 1990a, 1990b). Dimorphism has been recognized in these dwarfs, demonstrating that they are not the microconchs of cooccurring larger taxa. Because of their small size, these dwarf taxa have, in general, only been detected in exceptionally preserved faunas, such as those found in the concretions in shale and mudstone facies of the U.S. Western Interior.

OCCURRENCE: Middle Turonian Collignoniceras woollgari regulare Subzone of the Black Hills only.

Collignonicerites collisniger , new species Figure 49A–K, M–T

DERIVATION OF NAME: collis + niger (Latin) black hills, from the type area.

TYPES: Holotype is USNM 498294 (fig. 49M, R–T), paratypes USNM 498295–498302 (fig. 49A–K, N–Q; 498301 not illustrated), from the middle Turonian Carlile Shale, Collignoniceras woollgari regulare Subzone at locality 12 in fig. 1: USGS Mesozoic locality D13832 , Carlile Shale, middle Turonian, C. woollgari regulare Subzone , sec. 35, T. 8 S, R. 1 E, Fall River County, South Dakota.

DIAGNOSIS: With the characters of the genus.

DESCRIPTION: Coiling fairly involute (U/D = 0.26) and umbilicus moderately deep (table 6). The umbilical wall is flattened, subvertical, with an evenly rounded shoulder.

The whorl section is compressed, with greatest breadth below midflank in intercostal section, and shows broadly rounded inner flanks, flattened convergent outer flanks, and a relatively broad, flattened venter with a sharp siphonal keel. The greatest breadth is at the umbilical bullae in costal section. In strongly ornamented variants, blunt umbilical bullae, four to six per whorl, are present in middle growth. The bullae give rise to two or three primary ribs with up to three nonbullate long ribs separating the bullate groups. These nonbullate ribs arise either singly or in pairs at the umbilical shoulder to give a total of 16 ribs per half whorl. Ribs are broad, crowded, flexuous, and prorsiradiate, and each bears a small outer ventrolateral clavus from which the rib projects forward and declines in strength, intersecting the line of the siphonal keel in an acute chevron. The keel has even siphonal clavi, equal in number to but displaced adaperturally of the ventrolateral clavi. In feebly ornamented variants, the umbilical bullae are weak; the flanks bear only striae and lirae on the inner part but the ventrolateral part is similar to that already described. The umbilical bullae may decline on the adult body chamber, which may be constricted, while the crenulations on the siphonal keel become irregular.

The suture is the same as for the genus.

DISCUSSION: See under genus.

OCCURRENCE: As for types.

Figures

Fig. 10. Collignoniceras woollgari woollgari (Mantell, 1822). The lectotype BMNH 5682, the original of Mantell, 1822: plate 21, figure 6, from near Lewes, Sussex, England. Figures are ×1.

Fig. 17. Collignoniceras woollgari regulare (Haas, 1946), gracile form. A–C. USNM 498227; D– F. USNM 498217; G–I. USNM 498228; J, K. USNM 498229; L–N. USNM 498221; O–Q. USNM 498230; R, S. USNM 498231, all from locality 8. T, U. USNM 498232, from locality 12. V, W. USNM 498233, from locality 8. X, Y. USNM 498234, from locality 12. Z–B1. USNM 498223, from locality 8. All figures are ×1.

Fig. 18. Collignoniceras woollgari regulare (Haas, 1946), gracile form. A, B. USNM 498235, from locality 12. C, D. USNM 498236; E–G. USNM 498237, both from locality 8. All figures are ×1.

Fig. 19. Collignoniceras woollgari regulare (Haas, 1946), gracile form. USNM 498238, from locality 17. Figure is ×1.

Fig. 20. Collignoniceras woollgari regulare (Haas, 1946). A. USNM 498238, gracile form from locality 17. B–D. isolated ventrolateral spine, BHI 2103, from the lower part of the Carlile Shale in sec. 12, T 9 S, R 1 E, Fall River County, South Dakota. Collected by N. L. Larson. All figures are ×1.

Fig. 21. Collignoniceras woollgari regulare (Haas, 1946). A, B. USNM 498239, gracile form. C,

Fig. 49. A–K, M–T. Collignonicerites collisniger n. sp. A, B. paratype USNM 498295; C, D. paratype USNM 498296; E, F. paratype USNM 498297; G–I. paratype USNM 498298, J. paratype

Fig. 34. A–C. Collignoniceras jorgenseni n. sp., USNM 498250, a paratype, robust form from locality 20. D–H. Collignoniceras vermilionense (Meek and Hayden, 1860). D. cast of holotype, USNM 224; E. Copy of original figure of Meek, 1876a: plate 7, figure 2. Original is from a limestone concretion in the Carlile Shale, probably the middle Turonian Collignoniceras praecox Zone, on the Missouri River opposite the mouth of Vermillion (formerly Vermilion) River in Dixon County, Nebraska. F, G. USNM 299166, gracile form from locality 21. H. S. Jorgensen Collection CO1970a, Carlile Shale, Collignoniceras praecox Zone, dredged from Missouri River during natural gas pipeline construction at Yankton, South Dakota. All figures are ×1.

Fig. 35. A. Partial external suture of Collignoniceras vermilionense (Meek and Hayden, 1860). S. Jorgensen Collection no. CO1970A from the Middle Turonian C. praecox Zone, concretion dredged from Missouri River during natural gas pipeline construction at Yankton, South Dakota. B. Collignoniceras jorgenseni, n. sp. Partial external suture of paratype USNM 498253, collected by S. D. Jorgensen from the Middle Turonian C. praecox Zone, Carlile Shale at locality 16.

Fig. 36. Collignoniceras jorgenseni, n. sp. A. holotype, USNM 498249, robust form; B–D, K. Paratype USNM 498253, gracile form; both from locality 16. E–G. USNM 356918, robust form from the lower part of the Carlile Shale, center of sec. 35, T 8S, R 1E, Fall River County, South Dakota. H– J. Paratype USNM 498254, gracile form from locality 16. All figures are ×1.

Fig. 39. Collignoniceras praecox (Haas, 1946), gracile form. A–C. USNM 498268; D–F. USNM

Fig. 48. Collignoniceras percarinatum (Hall and Meek, 1856). A, B. USNM 498287; C, D. USNM 498288; E, F. USNM 498289; G, H. USNM 498290, all from locality 15. I. Paralectotype AMNH 46057; J. Copy of Hall and Meek’s original figure of AMNH 31995 (1856: pl. 4, fig. 2a). K, L. USNM 498291; M, N. USNM 498292; O, P. USNM 498293, all from locality 15. Q. Paratype AMNH 46058; R–U, V. lectotypes. R is a copy of the original figure of Hall and Meek (1856: pl. 4, fig. 2b) (AMNH 31994), U is AMNH 31994, and V is AMNH 30036, part and counterpart of the same specimen. All of the types (I, J, Q, R, U, V) are from rocks now assigned to the middle part of the Carlile Shale, ‘‘Five miles below the mouth of Vermilion River on the Missouri’’, that is to say, probably from the northeast side of Volcano Hill in sec. 3, T. 31N, R. 5E, Dixon County, Nebraska. S, T. USNM 299165 from locality 21. Figures A–I, K–P are X2; fig. J, Q–V are X1.