Search

Hoploscaphites criptonodosus (Riccardi, 1983) Figures 8C, D, 9, 11A, B, 23D, E, 26���38 1983. Jeletzkytes criptonodosus. Riccardi, p. 28, pl. 6, fig. 10; pl. 7, figs. 1, 2; pl. 8, figs. 7���9; text-figs. 25���27. 1983. Jeletzkytes cf. criptonodosus. Riccardi, p. 30, pl. 11, figs. 1���11, 15���21; text-figs. 28, 29b, 30, 31. non 1983. Jeletzkytes cf. criptonodosus. Riccardi, p. 30, pl. 11, figs. 12���14; text-fig. 29a (= Hoploscaphites sargklofak). 1994. Jeletzkyites (Karlwaageites) criptonodosus Riccardi. Cooper, p. 181. 1995. Jeletzkytes criptonodosus Riccardi, 1983. Cobban and Kennedy, p. 31, figs. 6.4, 6.5, 22.5���22.12, 23.1���23.5. 1997. Jeletzkytes criptonodosus Riccardi, 1983. Larson et al., p. 81, fig. on bottom; p. 82. top (= Riccardi, 1983, pl. 6, fig. 10, pl. 7, fig. 1). 2000. Jeletzkytes criptonodosus Riccardi, 1983. Kennedy et al., p. 26, fig. 12A, B. 2016. Jeletzkytes criptonodosus Riccardi, 1983. Klein, p. 138. EMENDED DIAGNOSIS: Macroconchs oval in lateral view; robust, with compressed subquadrate whorl section of shaft consisting of broadly rounded flanks and nearly flat venter; small umbilicus commonly with umbilical bulge; apertural angle averaging approximately 60��; ribbing coarse on the adapical end of the phragmocone, becoming finer on the body chamber; moderately closely spaced, medium sized ventrolateral tubercles; small umbilicolateral tubercles on phragmocone and body chamber; one or two rows of lateral tubercles on the outer flanks on the adapical end of the phragmocone; microconchs oval in lateral view; whorl section of shaft subquadrate with broadly rounded flanks converging toward ventrolateral shoulder; large umbilicus exposing earlier whorls; moderately closely spaced, medium sized ventrolateral tubercles; relatively prominent umbilicolateral tubercles on body chamber; one or two rows of lateral tubercles on the adapical end of the phragmocone; suture deeply incised, with a broad, asymmetrically bifid first lateral saddle and a narrow, symmetrically to asymmetrically bifid first lateral lobe (slightly modified from Riccardi, 1983). TYPES: The holotype and paratype are GSC 67104 and 67105, respectively, illustrated in Riccardi (1983: pl. 6, fig. 10; pl. 7, figs. 1, 2; pl. 8, figs. 7���9). They are both from GSC loc. 10374 from the Baculites baculus Zone of the Belanger Member of the Bearpaw Shale, on the north side of Frenchman River, sec. 14, T. 6, R. 25, W3rd Mer., Saskatchewan, Canada. MATERIAL: The collection consists of approximately 90 specimens of which 61 comprise the measured set (tables 3, 4) representing 43 macroconchs and 18 microconchs. The specimens in our collection are from the upper part of the Baculites baculus and B. grandis zones of the Pierre Shale in Wyoming, Colorado, Montana, and possibly South Dakota, and the Bearpaw Shale in Montana. MACROCONCH DESCRIPTION: In the measured sample, LMAX averages 79.2 mm and ranges from 60.9 to 102.4 mm (table 3). The ratio of the size of the largest specimen to that of the smallest is 1.68. The specimens form a broad size distribution, with a primary peak at 65���70 mm and a secondary peak at 75���80 mm (fig. 26). Adults are stout with an oval outline in side view. LMAX /HS averages 2.09 and ranges from 1.86 to 2.32 (2.04 in the holotype). USNM 463215 (fig. 33) is an example of a specimen with an oval outline (LMAX /HS = 2.27) and AMNH 108445 (fig. 30) is an example of a specimen with a more rounded outline (LMAX /HS = 1.98). The umbilicus is small and deep. The umbilical diameter averages 5.0 mm and ranges from 3.7 to 7.6 mm. UD/ LMAX averages 0.06 and ranges from 0.05 to 0.10. The umbilicus is unusually large (7.6 mm) in AMNH 108456 (fig. 31). In lateral view, the umbilical shoulder is straight and usually exhibits a pronounced umbilical bulge. Most specimens are tightly coiled with little or no gap between the phragmocone and hook. LMAX /HP 2 averages 2.83 and ranges from 2.59 to 3.04 (2.79 in the holotype). AMNH 95771 (fig. 32A���C) is an, Published as part of Landman, Neil H., Kennedy, W. James, Larson, Neal L., Grier, Joyce C., Grier, James W. & Linn, Tom, 2019, Description Of Two Species Of Hoploscaphites (Ammonoidea: Ancyloceratina) From The Upper Cretaceous (Lower Maastrichtian) Of The U. S. Western Interior, pp. 1-72 in Bulletin of the American Museum of Natural History 2019 (427) on page 44, DOI: 10.1206/0003-0090.427.1.1, http://zenodo.org/record/4613615, {"references":["Riccardi, A. C. 1983. Scaphitids from the Upper Campanian-lower Maastrichtian Bearpaw Formation of the Western Interior of Canada. Geological Survey of Canada Bulletin 354: 1 - 51."]}

Genus Hoploscaphites Nowak, 1911 [= Mesoscaphites Atabekian, 1979: 523 (nomen nudum) fide Kennedy, 1986; Wright, 1996; Jeletzkytes Riccardi, 1983: 14]. TYPE SPECIES: Ammonites constrictus J. Sowerby (1817: 189, pl. A, fig. 1), by original designation. DIAGNOSIS: ���Small to large scaphites, strongly dimorphic, with broad variation in degree of whorl compression ranging from slender to robust, with involute phragmocone, short to long shaft, and weakly recurved hook; apertural angle ranging from approximately 35�� to 85��; aperture constricted with dorsal projection; ribs straight to flexuous, increasing by branching and intercalation, with weak to strong adoral projection on venter; adult shell with or without umbilicolateral, flank, and ventrolateral tubercles; suture fairly indented, with symmetrically to slightly asymmetrically bifid first lateral lobe��� (Landman et al., 2010: 93). DISCUSSION: In their monograph on the scaphites of the ��� nodosus group,��� Landman et al. (2010) treated Jeletzkytes Riccardi, 1983, as a junior subjective synonym of Hoploscaphites. They argued that the shape of the shell, the pattern of ornamentation, and the complexity of the suture are the same in both genera, the only differences being the degree of compression and, as a result, the flexuosity of the ribs and the size of the tubercles. They noted that such variation already exists within the genus Hoploscaphites, as previously defined, and exemplified by the type species H. constrictus. Wright (1996: 261���262) cited the same reason for synonymizing the two genera: ���Separation of the large and inflated species of the nodosus group as Jeletzkytes seems unnecessary, given the great variation within most scaphitid species.��� Later, Cooper (1994) erected the new subgenus Karlwaageites for derived members of Jeletzkytes from North America that bear lateral tubercles. However, the number and distribution of lateral tubercles can vary even within a single species, casting doubt on the utility of this character for subgeneric separation. Until a thorough phylogenetic revision of all scaphitid genera and subgenera is undertaken, we prefer to follow a more conservative approach and treat all these species in the genus Hoploscaphites., Published as part of Landman, Neil H., Kennedy, W. James, Larson, Neal L., Grier, Joyce C., Grier, James W. & Linn, Tom, 2019, Description Of Two Species Of Hoploscaphites (Ammonoidea: Ancyloceratina) From The Upper Cretaceous (Lower Maastrichtian) Of The U. S. Western Interior, pp. 1-72 in Bulletin of the American Museum of Natural History 2019 (427) on page 22, DOI: 10.1206/0003-0090.427.1.1, http://zenodo.org/record/4613615, {"references":["Nowak, J. 1911. Untersuchungen uber die Cephalopoden der oberen Kreide in Polen. II Teil: die Skaphiten. Bulletin de l'Academie des Sciences de Cracovie Series B 7: 547 - 589.","Wright, C. W. 1996. Treatise on invertebrate paleontology: part L, Mollusca 4 (revised), Cretaceous Ammonoidea: 362 pp. Boulder, CO: Geological Society of America.","Riccardi, A. C. 1983. Scaphitids from the Upper Campanian-lower Maastrichtian Bearpaw Formation of the Western Interior of Canada. Geological Survey of Canada Bulletin 354: 1 - 51.","Sowerby, J. 1817. The mineral conchology of Great Britain, vol. 2. London: the author. [7 vols.]","Landman, N. H., W. J. Kennedy, W. A. Cobban, and N. L. Larson. 2010. Scaphites of the \" nodosus group \" from the Upper Cretaceous (Campanian) of the Western Interior of North America. Bulletin of the American Museum of Natural History 342: 1 - 242."]}

Hoploscaphites macer, n. sp. Figures 8A, B, 11C, D, 13–22, 23A–C, 24, 25 DIAGNOSIS: Macroconchs oval to nearly circular in lateral view; cross section of shaft compressed subovoid with high whorls consisting of broadly rounded flanks and nearly flat venter; maximum width at adoral part of shaft; small umbilicus commonly with umbilical bulge; ribs coarse on phragmocone at the point of exposure, subsequently becoming finer; small, moderately closely spaced ventrolateral tubercles; small umbilicolateral tubercles on body chamber; occasional lateral tubercles on adapical part of phragmocone; apertural angle averaging 56°; microconchs oval in lateral view; cross section of shaft subovoid with broadly rounded flanks converging toward ventrolateral shoulder; large umbilicus exposing earlier whorls; closely spaced ventrolateral tubercles; relatively prominent umbilicolateral tubercles on body chamber; suture with broad, asymmetrically bifid first lateral saddle and narrow, symmetrically to asymmetrically bifid first lateral lobe. ETYMOLOGY: The name is derived from the Latin word macer, “thin,” which is one’s first impression of this species relative to other species in the same biostratigraphic zones. Upon inspection, however, the shell is slightly inflated. Nevertheless, this name has been used informally for the last 20 years, and for the sake of stability, we decided to retain the name for this species. TYPES: The holotype is AMNH 71839 (figs. 19E–H, 23A), a macroconch, from the lower part of the B. grandis Zone of the Pierre Shale on the Cedar Creek Anticline, Montana. It is a steinkern with some attached shell 54.2 mm in diameter with a small umbilicus. The macroconch paratypes are AMNH 113323 (fig. 20D–F) and 113324 (fig. 20G–I), both from the upper part of the B. baculus Zone or the lower part of the B. grandis Zone of the Pierre Shale on the Cedar Creek Anticline, Montana, and USNM 713612 (fig. 17A–C) from the B. grandis Zone of the Bearpaw Shale in Roosevelt County, Montana. The microconch paratypes are AMNH 72634 (fig. 24 M–P) and 108314 (fig. 24 E–H) from the upper part of the B. baculus Zone or the lower part of the B. grandis Zone of the Pierre Shale on the Cedar Creek Anticline, Montana. MATERIAL: The collection consists of approximately 100 specimens of which 75 comprise the measured set (40 macroconchs and 35 microconchs) (tables 1, 2). All the specimens in our collection are from the upper part of the Baculites baculus Zone or lower part of the B. grandis Zone of the Pierre Shale in Wyoming, Colorado, and Montana and the Bearpaw Shale in Montana. MACROCONCH DESCRIPTION: In the measured sample, LMAX averages 61.4 mm and ranges from 45.2 to 76.0 mm (table 1). The ratio of the size of the largest specimen to that of the smallest is 1.68. The specimens form a broad size distribution, with a peak at 50–55 mm (fig. 13). Adults are slender with an oval to circular outline in side view. LMAX /HS averages 2.05 and ranges from 1.86 to 2.25 (1.94 in the holotype). BHI 4346 (fig. 14A–D) is an example of a specimen with an oval outline (LMAX /HS = 2.17) and AMNH 108487 (fig. 19A–D) is an example of a specimen with a more rounded, nearly perfectly circular outline (LMAX /HS = 1.98). The umbilicus is small and deep. The umbilical diameter averages 3.8 mm and ranges from 1.9 to 6.5 mm. UD/ LMAX averages 0.06 and ranges from 0.04 to 0.12. In lateral view, the umbilical wall is straight and usually exhibits a pronounced umbilical bulge, so that part of the umbilicus of the phragmocone is concealed. All specimens are tightly coiled with little or no gap between the phragmocone and hook. LMAX /HP 2 averages 2.78 and ranges from 2.55 to 2.98 (2.70 in the holotype). AMNH 76388 (fig. 18A–C) is an example of a tightly coiled specimen (LMAX /HP 2 = 2.75) and BHI 4346 (fig. 14A–D) is an example of a more loosely coiled specimen (LMAX /HP 2 = 2.89).