Colorado ammonites

45 p. : ill., maps ; 26 cm.Includes bibliographical references (p. 42-44).The upper part of the Pierre Shale and Fox Hills Formation were deposited in the late Cretaceous (Maastrichtian) Western Interior Seaway. They crop out in a belt that roughly parallels the Front Range of the Rocky Mountains from Douglas to Weld County, Colorado. These rocks consist of sandy shales and sandstones and are overlain by the nonmarine Laramie Formation. A sparse assemblage of ammonites is present consisting of Coahuilites sheltoni Böse, 1928, Sphenodiscus pleurisepta (Conrad, 1857), Trachybaculites sp. cf. T. columna (Morton, 1834), Hoploscaphites birkelundae Landman and Waage, 1993, Hoploscaphites sp. cf. H. birkelundae, Jeletzkytes dorfi Landman and Waage, 1993, and Jeletzkytes sp. cf. J. dorfi. Hoploscaphites birkelundae and Jeletzkytes dorfi define the H. birkelundae Zone in the Western Interior, which represents the lower part of the Upper Maastrichtian. These rocks are thus equivalent in age to the Fox Hills Formation in Niobrara County, Wyoming, and older than the type Fox Hills Formation in north-central South Dakota. An analysis of the ratio of ⁸⁷Sr/⁸⁶Sr in a belemnite from this zone in Morgan County, Colorado, yields a value of 0.707790 ± 0.000008 (2-sigma SE), nearly identical to that of a bivalve from the same zone in Niobrara County, Wyoming (McArthur et al., 1994). The western shoreline of the seaway during the time of H. birkelundae extended as far west as northwestern Colorado and southwestern Wyoming

Heteromorph ammonites

88 p. : ill., maps ; 26 cm.Includes bibliographical references (p. 80-85).Heteromorh ammonites of the families Nostoceratidae Hyatt, 1894, and Diplomoceratidae Spath, 1926, are common to abundant in sediments deposited in the western and central parts of the U.S. Western Interior Seaway during the early late Campanian. The indices of successive zones of Didymoceras nebrascense (Meek and Hayden, 1856a) (oldest), Didymoceras stevensoni (Whitfield, 1877), Exiteloceras jenneyi camacki, n. subsp., Exiteloceras jenneyi jenneyi (Whitfield, 1877) and Didymoceras cheyennense (Meek and Hayden, 1856a) are revised, as are Nostoceras monotuberculatum Kennedy and Cobban, 1993a (D. nebrascense and D. stevensoni zones), Oxybeloceras crassum (Whitfield, 1877) (D. stevensoni and E. jenneyi zones), and Spiroxybeloceras meekanum (Whitfield, 1877) (D. cheyennense zone). Solenoceras elegans, n. sp. (D. stevensoni and E. jenneyi zones), Solenoceras bearpawense, n. sp. (D. nebrascense zone), and Solenoceras larimerense, n. sp. (E. jenneyi zone) are also described

Ammonites of New Jersey

30 p. : ill., map ; 26 cm.Includes bibliographical references (p. 27-30).New fossil collections provide additional information about the late Campanian and Maastrichtian ammonites from the Navesink Formation of New Jersey. Late Campanian ammonites include Pseudophyllites indra (Forbes, 1846), Nostoceras (N.) approximans (Conrad, 1855) (of which Nostoceras (N.) stantoni Hyatt, 1894, is a synonym), Nostoceras (N.) hyatti Stephenson, 1941, Nostoceras (N.) pauper (Whitfield, 1892), Didymoceras cf. D. draconis (Stephenson, 1941), Exiteloceras rude n. sp., Hoploscaphites pumilus (Stephenson, 1941), and Jeletzkytes cf. J. nodosus (Owen, 1852). Maastrichtian ammonites from the Navesink Formation include Pachydiscus (P.) neubergicas neubergicus (Hauer, 1858), Kitchinites sp., Nostoceras (N.) alternatum (Tuomey, 1854), Baculites sp., Eubaculites cf. E. labyrinthicus (Morton, 1834), Eubaculites sp.?, Jeletzkytes cf. J. plenus (Meek, 1876), Jeletzkytes criptonodosus Riccardi, 1983, and Discoscaphites gulosus (Morton, 1834). These faunas are correlated with those of Western Europe, the Gulf Coast, and the Western Interior of the United States. The older fauna from the basal phosphatic beds of the Navesink Formation at the classic Atlantic Highlands locality is referred to the Nostoceras (N.) hyatti zone. It is late Campanian in age and equivalent to the Nostoceras (N.) pozaryskii/Belemnella langei zone in Europe and the Baculites jenseni zone in the United States Western Interior. In addition, these beds contain ammonites that range into the early Maastrichtian, as well as Pachydiscus (P.) neubergicus, whose appearance marks the base of the Maastrichtian. Thus, these phosphatic beds represent a condensed sequence that spans the late Campanian to early Maastrichtian. Ammonites also occur at other localities in the Navesink Formation in New Jersey, and correspond to higher levels in the Maastrichtian. The youngest ammonite known from the Navesink Formation, Discoscaphites gulosus, from Sewell, New Jersey, indicates a correlation with the Hoploscaphites nicolletii or Jeletzkytes nebrascensis zone of the Western Interior

A Gigantic Shark from the Lower Cretaceous Duck Creek Formation of Texas

Author Contributions Conceived and designed the experiments: JAF SNS JAD-F. Analyzed the data: JAF SNS. Wrote the paper: JAF SNS. Site data for OMNH V1727 are available by request from the department of vert. paleontology at the (SN)OMNH.Three large lamniform shark vertebrae are described from the Lower Cretaceous of Texas. We interpret these fossils as belonging to a single individual with a calculated total body length of 6.3 m. This large individual compares favorably to another shark specimen from the roughly contemporaneous Kiowa Shale of Kansas. Neither specimen was recovered with associated teeth, making confident identification of the species impossible. However, both formations share a similar shark fauna, with Leptostyrax macrorhiza being the largest of the common lamniform sharks. Regardless of its actual identification, this new specimen provides further evidence that large-bodied lamniform sharks had evolved prior to the Late Cretaceous.Ye