Goniatites Zone (middle Mississippian) ammonoids of the Antler Foreland Basin (Nevada, Utah)

Abstract

The ammonoid faunas from the <i>Goniatites </i>Zone (Late Viséan; Mississippian) of the Camp Canyon Member (Chainman Formation) are described for the first time. The assemblage shows close relationships to time equivalent occurrences in Alaska and the American Midcontinent, but differs markedly from occurrences in Europe, North Africa, and the South Urals. Seven successive ammonoid biozones are proposed for this interval in North America, in ascending order: (1) <i>Calygirtyoceras confusionense </i>Ammonoid Biozone, (2) <i>Calygirtyoceras arcticum </i>Ammonoid Biozone, (3) <i>Girtyoceras primum </i>Ammonoid Biozone, (4) <i>Girtyoceras gordoni </i>Ammonoid Biozone, (5) <i>Goniatites deceptus </i>Ammonoid Biozone, (6) <i>Goniatites eganensis </i>Ammonoid Biozone, and (7) <i>Goniatites multiliratus </i>Ammonoid Biozone. The following ammonoid species are revised or newly described: <i>Bollandoceras occidentale </i>sp. nov., <i>Entogonites burbankensis </i>sp. nov., <i>Entogonites borealis </i>(Gordon, 1957), <i>Entogonites acus </i>sp. nov., <i>Calygirtyoceras confusionense </i>sp. nov., <i>Calygirtyoceras arcticum </i>Gordon, 1957, <i>Girtyoceras primum </i>sp. nov., <i>Girtyoceras gordoni </i>sp. nov., <i>Girtyoceras hamiltonense </i>sp. nov., <i>Dimorphoceras worki </i>sp. nov., <i>Dimorphoceras rileyi </i>sp. nov., <i>Metadimorphoceras mangeri </i>sp. nov., <i>Metadimorphoceras richardsi </i>sp. nov., <i>Kazakhoceras bylundi </i>sp. nov., <i>Goniatites americanus </i>Gordon, 1971, <i>Goniatites deceptus </i>sp. nov., <i>Goniatites eganensis </i>sp. nov., <i>Goniatites sowerbyi </i>sp. nov., and <i>Praedaraelites loeblichi </i>(Miller and Furnish, 1940)

Late Viséan (late Mississippian) ammonoids from the Barnett Shale, Sierra Diablo Escarpment, Culberson County, Texas, USA

“…Specimens of Goniatites multiliratus from bed 17 indicate that the zone for that species can also be diagnosed in that general part of the section. This same general succession can be observed entirely, or in part, in the Chainman Shale of Nevada and Utah, the Caney Shale of Oklahoma, and Moorefield Formation of Arkansas (Korn and Titus, 2011).…”

“…High-resolution global correlations for the Late Viséan (Asbian and Brigantian in the British subdivision scheme) ammonoids of North America were proposed by Korn and Titus (2011). Our work on the Sierra Diablo sections has not substantively changed this earlier interpretation and no further discussion on correlation of pre-Choctawites kentuckiensis Biozone assemblages is warranted.…”

“…-The ammonoids Goniatites eganensis and Girtyoceras hamiltonense were discovered from the base of the measured section, as well as other localities to the south, indicating that the Goniatites eganensis Biozone, which was first delineated in the Chainman Shale of Utah and Nevada (Korn and Titus, 2011), is the lowest in the Sierra Diablo Barnett section that can be diagnosed with in situ material (Fig. 2).…”

“…These concretion fragments were derived from our beds 9, 11, and 13. The only ammonoids we collected from these loose pieces were specimens of Goniatites eganensis Korn and Titus, 2011. The lowest 7 m of exposed section did not yield in situ threedimensional ammonoids, only rare leiorhynchid and lingulid brachiopods and Nereites-type trace fossils.…”

“…Previously, the entire post-Goniatites multiliratus interval has been lumped into a single "Goniatites gra- Figure 3. Global correlation chart for upper Viséan and lowest Serpukhovian ammonoid zones; after Ruzhencev and Bogoslovskaya (1971), Korn and Horn (1996), , Korn and Kaufmann (2009) and Korn and Titus (2011). nosus" (now referred to as Lusitanoceras Pereira de Sousa, 1923) Biozone (Gordon, 1965;Saunders et al, 1977;Webster et al, 1984). It is now clear to us that both the taxonomy and biostratigraphy of this interval in North America is much more complicated and can be subdivided in the eastern USA using species of the characteristic genus Choctawites.…”