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1

A survey of the Cretaceous ammonite Placenticeras Meek, 1876, in the United States Western Interior, with notes on the earliest species from Texas

Cobban W., Kennedy W. J.

Acta Geologica Polonica

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2016

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Vol. 66, no. 4

587--608

EN

This contribution documents the record of the late Cretaceous ammonite Placenticeras Meek, 1876, from the late Cenomanian of Texas and the southern part of the U. S. Western Interior up to the late Middle Campanian zone of Baculites scotti, reconstructed and updated from an incomplete manuscript by the late W. A. Cobban based on the collections of the U. S. Geological Survey. The original manuscript dates from the late 1980’s, and there is now additional information on the occurrence of the genus that is incorporate here; much of this comes from Neal Larson of Hill City, South Dakota, to whom I am indebted for his help in preparing Bill’s manuscript for publication. It now provides an objective documentation of the distribution of Placenticeras in space and time on which any subsequent analysis of the evolution of the genus will depend.

2

Testing the congruence of the macrofossil versus microfossil record in the Turonian-Coniacian boundary succession of the Wagon Mound-Springer composite section (NE New Mexico, USA)

Walaszczyk I., Lees J., Peryt D., Cobban W., Wood C.

Acta Geologica Polonica

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2012

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Vol. 62, no. 4

581-594

EN

The Turonian-Coniacian boundary succession from the Wagon Mound-Springer composite section in the US Western Interior shows a virtually identical macrofaunal record to that revealed in the proposed candidate Coniacian GSSP in the Salzgitter-Salder-Slupia Nadbrzezna composite section in central Europe, with easy identification in both regions of the base of the Coniacian Stage, as defined by the first appearance of the inoceramid bivalve species, Cremnoceramus deformis erectus (Meek). The macrofaunal boundary definition is additionally confirmed by the foraminiferal and nannofossil data, demonstrating the high potential of the inoceramid marker for the base of the Coniacian. The former claims about distinct diachroneity between macrofossil and microfossil dates in the trans-Atlantic correlations, resulted from methodological deficiencies, and have no factual basis.

3

Palaeontology and biostratigraphy of the Middle-Upper Coniacian and Santonian inoceramids of the US Western Interior

Walaszczyk I., Cobban W.

Acta Geologica Polonica

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2006

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Vol. 56, no. 3

241-348

EN

The taxonomy of the Middle-Late Coniacian and Santonian inoceramids of the US Western Interior, including some specimens from the Canadian Western Interior, is revised, based mainly on the extensive collections of the US Geological Survey. The classic Meek and Hayden material is discussed. Forty-four species are described of which 5 are new: Inoceramus americanus, Inoceramus sokolovi, Inoceramus robertsoni, Inoceramus glacierensis, and Sphenoceramus gilli. The Middle Coniacian to Santonian inoceramids of the Western Interior represent a uniform Euramerican fauna. This allows the application of a uniform biostratigraphical zonation throughout the whole biogeographical region. Starting in the Late Coniacian, inoceramid faunas are characterised by relatively strong north.south biogeographic differentiation. The inoceramid zonation applied is discussed, diagnosed, and compared to previously used schemes, and to the ammonite zonation commonly used in the US Western Interior.

4

Campanian (Late Cretaceous) Ammonites from the upper part of the Anacacho Limestone in South-Central Texas

Kennedy W., Cobban W.

Acta Geologica Polonica

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2001

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Vol. 51, nr 1

15-30

EN

The ammonite assemblage from the upper part of the Anacacho Limestone in Medina Country in south-central Texas consists of Pachydiscus (Pachydiscus) travisi (ADKINS, 1929), Pachydiscus (P.) sp., Pachydiscus (P.) streckeri (ADKINS, 1928), Hoplitoplacenticeras (H.) marroti (COQUAND, 1859), Eubostrychoceras reevesi (YOUNG, 1963), Bostrychoceras polyplocum (ROEMER, 1841), Lewyites clinensis (ADKINS, 1929), Baculites taylorensis ADKINS, 1929, and Trachyscaphites spiniger porchi (ADKINS, 1929). Several of these species are also found in the Pecan Gap Chalk in central and northeastern Texas and in the basal part of the Demopolis Formation in Mississippi and Alabama. The fauna is probably contemporaneous with the Baculites asperiformis zone in the U.S. Western Interior, which lies in the lower part of the middle Campanian in the sense of the Western Interior threefold division of the Campanian. In terms of the European twofold division of the Campanian the fauna lies in the lower part of the upper Campanian

5

Pueblo, Colorado, USA, candidate Global Boundary Stratotype Section and Point for the base of the Turonian Stage of the Cretaceous and for the base of the Middle Turonian Substage, with a revision of the Inoceramidae (Bivalvia)

Kennedy W., Walaszczyk I., Cobban W.

Acta Geologica Polonica

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2000

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Vol. 50, no. 3

295-334

EN

An updated account of the candidate Global Boundary Stratotype Section and Point for the base of the Turonian Stage and the base of the Middle Turonian Substage in the Bridge Creek Member of the Greenhorn Limestone exposed in the Rock Creek Anticline west of Pueblo, Colorado is provided. Key ammonite distributions are revised and marker species illustrated. A taxonomic revision of the uppermost Cenomanian to lower Middle Turonian bivalve family Inoceramidae provides, for the first time, an adequately documented detailed zonation for the interval in the form of five successive partial range zones based on species of the genus Mytiloides. These are successive zones of M. hattini ELDER (uppermost Cenomanian), M. puebloensis n. sp., M. kossmati (HEINZ), M. mytiloides (MANTELL)(all Lower Turonian) and M. subhercynicus (SEITZ) (lower Middle Turonian). The base of the Turonian, defined by the first appearance of the ammonite Watinoceras devonense (WRIGHT & KENNEDY) at the base of bed 86 of the Bridge Creek Member corresponds to the first occurrence of Mytiloides puebloensis, and the base of the puebloensis Zone. The base of the Middle Turonian, defined bythe first occurrence of the ammonite Collignoniceras woollgari (MANTELL) in bed 120 of the Bridge Creek Members is just bellow the first occurrence of M. subhercynicus in bed 121, and the base of the sybhercynicus Zone.

6

Maastrichtian (Late Cretaceous) ammonites from the Owl Creek Formation in northeastern Mississippi, U.S.A

Kennedy W., Cobban W.

Acta Geologica Polonica

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2000

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Vol. 50, no. 1

175-190

EN

Ammonites are locally abundant in the Owl Creek Formation in northeastern Mississippi. The assemblage is dominated numerically by Eubaculites carinatus (MORTON, 1834), a widely distributed marker fossil for the Maastrichtian that also occurs in South America, sothern Africa, Madagascar, western Australia, southern India, and western Europe. It is accompanied by Sphenodiscus pleurisepta (CONRAD, 1857), Baculites cf. B. claviforms STEPHENSON, 1941, B. cf. undatus STEPHENSON, 1941, Discoscaphites iris (CONRAD 1858), D. sphaeroidalis sp. nov., and D. cf. D. conradi (MORTON, 1834)

7

Heteromorph ammonites from the Upper Campanian (Upper Cretaceous) Baculites cuneactus and Baculites reesidei zones of the Pierre Shale in Colorado, USA

Kennedy W., Cobban W., Scott G.

Acta Geologica Polonica

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2000

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Vol. 50, no. 1

1-20

EN

Calcareous sandstone concretions in the Upper Cretaceous Pierre Shale in Middle Park and in the Fort Collins area of Colorado in the U.S. Western Interior contain heteromorph ammonites of the families Nostoceratidae HYATT, 1894, and Diplomoceratidae SPATH 1926. The following species are described: Nostoceras cf. N. approximans (CONRAD 1855), Nostoceras cf. N. obtusum HOWARTH 1965, N. larimerense sp. nov., Nostoceras cf. N. splendidum (SHUMARD 1861) Didymoceras aurarium sp. nov., D. draconis (STEPHENSON 1941) Cirroceras conradi (MORTON 1841), Anaklinoceras minutum sp. nov., Solenoceras texanum (SHUMARD 1861), Solenoceras cf. S. reesidei STEPHENSON 1941, Lewyites oronensis (LEWY 1969) and Lewyites? sp. All these species are migrants from the Gulf coastal region. Didymoceras draconis and Cirroceras conradi are also known from the Delaware - New Jersey area and these two species, together with Solenoceras texanum are known from as far away as Israel

8

Heteromorph ammonites from the middle Campanian Baculites scotti Zone in the U.S. Western Interior

Kennedy W., Cobban W., Scott G.

Acta Geologica Polonica

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2000

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Vol. 50, no. 2

223-241

EN

The occurrence of organic soil cover in river valleys is typical regions that were to areal deglaciation. This feature results from the adaptation of a series of linear depressions of glacial melt-out origin by rivers for their flow. Such a series of depressions, primarily composing overflow lakes, underwent subsequent infilling with mainly lake and marsh deposits. These very thick deposits, characterised by high sorption potential and developed in the form of continuous structures, can be considered as effective protection layers, isolating groundwater from contamination

9

Campanian (Late Cretaceous) ammonites from the Bergstrom Formation in Central Texas

Kennedy W., Cobban W.

Acta Geologica Polonica

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1999

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Vol. 49, no. 1

67-80

EN

The occurrence of organic soil cover in river valleys is typical regions that were to areal deglaciation. This feature results from the adaptation of a series of linear depressions of glacial melt-out origin by rivers for their flow. Such a series of depressions, primarily composing overflow lakes, underwent subsequent infilling with mainly lake and marsh deposits. These very thick deposits, characterised by high sorption potential and developed in the form of continuous structures, can be considered as effective protection layers, isolating groundwater from contamination.

10

The Turonian - Coniacian boundary in the United States Western Interior

Walaszczyk I., Cobban W.

Acta Geologica Polonica

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1998

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Vol. 48, no. 4

495-507

EN

The Turonian/Coniacian boundary succession in the United States Western Interior is characterized by the same inoceramid faunas as recognized in Europe, allowing the application of the same zonal scheme in both regions; Mytiloides scupini and Cremnoceramus waltersdorfensis zones in the tompost Turonian and Cremnoceramus deformis erectus Zone in the lowermost Coniacian. The correlation with Europe is enhanced, moreover, by a set of boundary events recognized originally in Europe and well represented in the Western Interior: Didymotis I Event and waltersdorfensis Event in the tompost Turonian, and erectus I, II and ?III events in the Lower Coniacian. First "Coniacian" ammonite, Forresteria peruana, appears in the indisputable Turonian, in the zone of M. scupini, and the reference to Forresteria in the boundary definition should be rejected. None of the North American sections, proposed during the Brussels Symposium as the potential boundary stratotypes, i.e. Wagon Mound and Pueblo sections, appears better than the voted section of the Salzgitter-Salder. The Pueblo section is relatively complete but markedly condensed in comparison with the German one, but it may be used as a very convenient reference section for the Turonian/Coniacian boundary in the Western Interior. The Wagon Mound section was mis-interpreted in respect of its biostratigraphical position and is entirely of Late Turonian age.