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Lower Pennsylvanian (Morrowan) Ammonoids from the North American Midcontinent
- Walter L. Manger, W. Bruce Saunders
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- Journal:
- Journal of Paleontology / Volume 54 / Issue S10 / May 1980
- Published online by Cambridge University Press:
- 22 December 2017, pp. 1-56
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The Lower Pennsylvanian Hale Formation, which comprises the lower portion of the type Morrowan Series, in northwestern Arkansas, is subdivided into the Cane Hill and overlying Prairie Grove Members. The Cane Hill Member includes interbedded shale and sandstone with a basal conglomerate containing clasts reworked from underlying, truncated Mississippian formations. The Prairie Grove Member is highly variable, but includes sandy biosparite and calcareous sandstone. Highly fossiliferous pebble conglomerate and calcirudite lenses occur sporadically throughout the Hale Formation. Ammonoids and conodonts show that the Cane Hill-Prairie Grove boundary is unconformable.
Several thousand ammonoids collected from more than 100 localities in the Hale Formation show that four ammonoid zones and two subzones are recognizable in the Hale succession, and consequently in the redefined Halian Stage of the Morrowan Series. These are, in ascending order, the Retites semiretia, Quinnites henbesti, Arkanites relictus (including the Arkanites relictus relictus and overlying Cancelloceras huntsvillense Subzones) and Verneuilites pygmaeus Zones. Halian Stage ammonoids are known primarily from northern Arkansas, but an upper Arkanites relictus Zone (Cancelloceras huntsvillense Subzone) ammonoid assemblage occurs in the Primrose Member of the Golf Course Formation in south central Oklahoma.
Conodont-ammonoid associations in the Hale sequence provide a basis for integration of independently based zonal information. Rhachistognathus primus Zone conodonts occur in the Retites semiretia Zone; the Idiognathoides sinuatus Zone ranges through the Quinnites henbesti and Arkanites relictus relictus Subzone. The overlying Cancelloceras huntsvillense Subzone and Verneuilites pygmaeus Zone both contain conodonts of the Neognathodus symmetricus Zone.
The Hale ammonoid succession has few, if any, species in common with the type Namurian of Europe, but numerous genera are common to both sequences and the generic successions coincide and are equivalent in degree of development. The Retites semiretia Zone is equivalent to the Reticuloceras circumplicatile Zone (R1a); the Quinnites henbesti and lower Arkanites relictus Zones correspond to some portion of the R2b–R2c interval; and the upper Arkanites relictus Zone and the Verneuilites pygmaeus Zone correlate to Zone G1. The Retites semiretia Zone correlates to the lower Reticuloceras-Baschkortoceras Genozone (Nm2b1) of the upper Namurian in the south Urals; the Quinnites henbesti Zone is equivalent to some portion of the Nm2b2–3 intervals of this zone; the lower Arkanites relictus Zone is equivalent to the lower Bilinguites-Cancelloceras Genozone (Nm2c1) and the upper Arkanites relictus and Verneuilites pygmaeus Zones correspond to the uppermost interval (Nm2c2) in the south Urals sequence.
Systematic descriptions of biostratigraphically significant Halian taxa, including Reticuloceras tiro Gordon, R. wainwrighti Quinn, Retites semiretia McCaleb, Arkanites relictus relictus (Quinn, McCaleb, and Webb), A. relictus redivivus n.subsp., Quinnites n.gen. (type species Q. henbesti (Gordon)), Q. textum (Gordon), Bilinguites eliasi n.sp., Cancelloceras huntsvillense n.sp., and Verneuilites pygmaeus (Mather) are also presented.
Mid-Carboniferous Ammonoid Biostratigraphy, Southern Nye County, Nevada: Implications of the First North American Homoceras
- Alan L. Titus, Walter L. Manger
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- Journal:
- Journal of Paleontology / Volume 75 / Issue S55 / July 2001
- Published online by Cambridge University Press:
- 11 August 2017, pp. 01-31
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The Scotty Wash Formation on the Nevada Test Site (NTS), southern Nye County, Nevada has produced the first North American representatives of the globally significant index ammonoids Homoceras s.s. and Isohomoceras s.s. and contains the only ammonoid succession across an uninterrupted mid-Carboniferous boundary sequence known in North America.
Four ammonoid assemblages can be recognized at NTS that are homotaxial with the reference successions for the middle and upper Arnsbergian (E2) and Chokierian (H1) Stages, Namurian Series, in western Europe, and their equivalents worldwide. The upper Mississippian (Chesterian) portions of the NTS sections yield assemblages referable to a Eumorphoceras girtyi Ammonoid Biozone, representing the middle Arnsbergian Stage (E2b), followed by a Delepinoceras thalassoide Ammonoid Biozone, equivalent to the upper Arnsbergian Stage (E2c). The latter ammonoid biozone also occurs in the Imo and Rhoda Creek Formations of Arkansas and Oklahoma, requiring reassignment of those formations to the upper Arnsbergian Stage (E2c). The appearance of the Isohomoceras subglobosum Ammonoid Biozone marks the base of the Chokierian Stage (H1a) at NTS. The zonal name-bearer continues into lower Pennsylvanian (Morrowan) strata, where it joins the Homoceras coronatum coronatum Ammonoid Biozone assemblage in an interval equivalent to the upper Chokerian Series (H1b). A pronounced unconformity at NTS separates the Scotty Wash Formation from the overlying Tippipah Limestone, which contains a fifth ammonoid assemblage characterized by Cancelloceras cf. C. elegans that is equivalent to the Yeadonian Stage (G1), Namurian Series, of western Europe.
The conodont succession recovered from the ammonoid-bearing sections at NTS allows refined correlation of the Arnsbergian and Chokierian Stages with the Mid-Carboniferous Global Stratotype Section and Point (GSSP) at nearby Arrow Canyon, Nevada, and the North American midcontinent. The Lower Rhachistognathus muricatus Conodont Biozone of western North America is equivalent to the upper Arnsbergian Stage (E2c), and must include the upper portion of the Adetognathus unicornis Conodont Biozone as recognized in the midcontinent. The Upper R. muricatus Conodont Biozone is equivalent to that portion of the Chokierian Stage (H1a) below the appearance of Declinognathodus noduliferus, marking the mid-Carboniferous boundary horizon, including some of the R. primus Conodont Biozone as used in the North American midcontinent. The intercontinental mid-Carboniferous boundary, drawn at the appearance of D. noduliferus, does not correspond to the Arnsbergian-Chokierian Stage boundary (E2c-H1a) that is defined by the appearance of Isohomoceras subglobosum. A significant break occurs in the Arrow Canyon GSSP less than 4 m above the position of the mid-Carboniferous boundary, where Chokerian strata (H1) are probably succeeded by Kinderscoutian strata (R1). Higher at Arrow Canyon, the position of the Scotty Wash-Tippipah unconformity juxtaposes Kinderscoutian and Yeadonian (G1) strata and the entire upper Namurian Series is limited to no more than 54 m.
Comparison of Eurasian and North American ammonoid assemblage compositions suggests that at least intermittent faunal interchange persisted between the two regions until at least the close of the Chokierian.
Definition of the Mississippian-Pennsylvanian boundary, which has never been defined faunally in either type area, to correspond to the intercontinental mid-Carboniferous boundary would be compatible with relationships known in the Chesterian and Morrowan type areas.
Taxonomic treatment of the Chokierian ammonoid assemblage from Syncline Ridge, NTS provided herein includes Proshumardites karpinskii Rauser-Tschernoussova, 1928; Eosyngastrioceras inexpectans Titus, 2000; Somoholites cf. S. merriami (Miller and Furnish, 1940b); Euroceras ellipsoidale Ruzhencev and Bogoslovskaya, 1971a; Isohomoceras subglobosum (Bisat, 1924); Homoceras diadema (Beyrich, 1837); H. coronatum coronatum (Haug, 1898); and H. leedomi new species.
Masonoceras, a new karagandoceratid ammonoid from the lower Mississippian (lower Osagean) of Kentucky
- David M. Work, Walter L. Manger
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- Journal:
- Journal of Paleontology / Volume 76 / Issue 3 / May 2002
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- 14 July 2015, pp. 574-577
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Karagandoceratids are a rare offshoot of the Prionoceratinae, resembling that subfamily in general conch form and sutural ontogeny, but differing by possession of an acute ventral margin and an increasingly trifid ventral lobe. The systematic position of the Karagandoceratidae has been controversial [see Bartzsch and Weyer (1988) for an exhaustive review]. The nominate genus, Karagandoceras Librovitch, 1940 (type species, K. galeatum), possesses a weakly divided ventral lobe which has led authors to refer it to both the Praeglyphioceratina (Ruzhencev, 1960, 1962; Bogoslovsky, 1971; Ruzhencev and Bogoslovskaya, 1978; Bogoslovskaya et al., 1999; Kusina, 2000) and the Goniatitina (Weyer, 1965, 1972; Kullmann, 1981). Discovery of an ancestral karagandoceratid genus, gen. nov. I aff. Karagandoceras Bartzsch and Weyer, 1988, in the early Tournaisian Siphonodella sandbergi conodont Zone in Germany provided clarification on the proximate origin of Karagandoceras and provided a plausible link to the early Tournaisian prionoceratin genus Nicimitoceras Korn, 1993 (type species, Imitoceras subacre Vöhringer, 1960). Bartzsch and Weyer (1988) proposed a karagandoceratid phylogeny beginning with gen. nov. I aff. Karagandoceras in the early Tournaisian, progressing through Karagandoceras in the middle Tournaisian, and culminating with a third, descendent genus, gen. nov. II aff. Karagandoceras (typical species, Karagandoceras bradfordi Manger, 1971), early in the late Tournaisian. Bartzsch and Weyer (1988) elected to leave both the initial and final members of this lineage, gen. nov. I and gen. nov. II aff. Karagandoceras, in open nomenclature pending discovery of more completely preserved material. Discovery of superbly preserved representatives of a new species of gen. nov. II aff. Karagandoceras from the Borden Formation in northeastern Kentucky provides additional sutural and morphological details that support Bartzsch and Weyer's phylogenetic interpretation and makes formal description of this terminal karagandoceratid taxon (herein designated Masonoceras new genus) possible.
Morrowan lithistid demosponges and hexactinellids from the Ozark Mountains of northwestern Arkansas
- J. Keith Rigby, Walter L. Manger
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- Journal:
- Journal of Paleontology / Volume 68 / Issue 4 / July 1994
- Published online by Cambridge University Press:
- 14 July 2015, pp. 734-746
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Silicified and well-preserved specimens of the new orchocladine anthaspidellid genus and species, Virgaspongia ichnata, the rhizomorine haplistiid, Haplistion sphaericum Finks, 1960, and various root tufts, and the new hexactinellid species Steioderma hadra are reported from the Brentwood Member of the Morrowan Bloyd Formation from the Sulphur City quadrangle, in the Ozark Mountains of northwestern Arkansas. Virgaspongia is a subcylindrical branched or unbranched sponge that lacks a spongocoel and has a dendroclone-based skeleton in which trabs diverge upward and outward from an axial region. It is abundant here but is one of only a few anthaspidellid genera known from the Pennsylvanian. This is the first record of Haplistion from Pennsylvanian rocks of Arkansas, although the genus is widespread in upper Paleozoic rocks. The new hexactinellid species, Stioderma hadra, also documents the first occurrence of that genus from Arkansas and in Morrowan rocks. Only fragments were recovered but the swollen grotesque spicules, of several sizes, that make the fused dermal layer and outer sponge wall are distinctive, particularly where combined with an inner layer(?) or root tuft of monaxons of various sizes. Two different root tufts and one demosponge wall fragment(?) also occur in the collection.
Ontogeny and heterochrony in the Middle Carboniferous ammonoid Arkanites relictus (Quinn, McCaleb, and Webb) from northern Arkansas
- Daniel A. Stephen, Walter L. Manger, Cathy Baker
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- Journal:
- Journal of Paleontology / Volume 76 / Issue 5 / September 2002
- Published online by Cambridge University Press:
- 14 July 2015, pp. 810-821
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The reticuloceratid ammonoid Arkanites relictus (Quinn, McCaleb, and Webb, 1962) is represented by hundreds to thousands of individuals from horizons isolated both stratigraphically and geographically in northern Arkansas. These assemblages appear to represent mass mortality events resulting from a semelparous reproductive strategy. Arkanites relictus occurs as a dimorphic pair (depressed, widely umbilicate, cadiconic conchs and compressed, narrowly umbilicate, pachyconic conchs) thought to reflect sexual dimorphism. Late stage ontogenetic modifications, such as septal crowding and change in aperture profile, are widely cited evidence of sexual maturity in ammonoids. Septal crowding begins at a predictable ontogenetic stage in the compressed forms of A. relictus, but specimens with cadiconic conchs do not have crowded septa even at the largest diameters available.
Depending on the trait examined and the proxy for age of individuals, the dimorphism in Arkanites relictus (using the depressed form as the reference morph) is the result of acceleration, neoteny, or hypermorphosis plus neoteny. If size (diameter) is considered a proxy for age, the dimorphs were the same age at death, and the septa in the compressed variants developed via acceleration relative to the depressed variants. Regarding conch shape (width vs. diameter), the compressed morphs developed via neoteny relative to the depressed morphs. If septal count is considered a proxy for age, the dimorphs were not the same age at death, and the compressed forms were produced by a combination of hypermorphosis plus neoteny, i.e., they grew longer yet slower than the depressed forms. In A. relictus, the heterochronic processes of hypermorphosis and neoteny may have been operating simultaneously, which is an interesting possibility because it is an example of a combination of both peramorphic and paedomorphic processes.
Examining the Creation-Evolution Issue as a Humanities Course
- Walter L. Manger
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- Journal:
- The Paleontological Society Papers / Volume 5 / October 1999
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- 21 July 2017, pp. 235-242
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- October 1999
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In early 1981, the 73rd General Assembly of the State of Arkansas in regular session passed Senate Bill 482 without debate. Governor Frank White, immediately signed the bill, admitting that he hadn't read it, and it became state law as Act 590, the “Balanced Treatment for Creation-Science and Evolution-Science Act.” A suit on behalf of 23 plaintiffs was filed by the American Civil Liberties Union (ACLU) on May 27, 1981, and a trial before Federal Judge William Overton was scheduled for October and then postponed until December, 1981. The trial began on December 7, 1981, and it received national attention. The ACLU called well-known expert witnesses in both religion (Bruce Vawter, George Marsden, and Langdon Gilkey) and science (Francisco Ayala, G. Brent Dalrymple, Stephen Jay Gould, and Carl Sagan). The state's witnesses were creationists associated with the Geoscience Research Institute, Loma Linda University, California (Harold Coffin, Ariel Roth), and the Creation Research Society, Ann Arbor, Michigan (Wayne Friar, Margaret Helder, Donald Chittick, Robert Gentry). Its “star” witness, at least in the eyes of the press, was Chandra Wickramasinghe, University College of Wales. The trial did not involve any of the high profile creationists, such as Henry Morris or Duane Gish, from the Institute for Creation Research (ICR) in San Diego, even though it was disclosed that Wendall R. Bird, an attorney associated with (ICR), had written the act. Both sides called local educators. Judge Overton issued his ruling and an injunction permanently prohibiting enforcement of Act 590 on January 5, 1982. The state did not appeal his ruling.