David M. Work

Cyclothem [“digital”] correlation and biostratigraphy across the global Moscovian-Kasimovian-Gzhelian stage boundary interval (Middle-Upper Pennsylvanian) in North America and eastern Europe

The long-standing difficulty of correlating Pennsylvanian strata among provincial faunal regions is resolved by effecting “digital” correlation of major glacial-eustatic cyclothems that represent high-stands when certain species achieved more global distribution than usual. In the late Moscovian–early Gzhelian (late Desmoinesian–early Virgilian) succession in the midcontinent United States, several major cyclothems are correlated, by both conodont species in common and cyclothem scale, with cyclothems in Russia (Moscow Basin) and Ukraine (Donets Basin), and the remaining cyclothems fit into the framework by position and scale. In this way the suggested event marker for the global Kasimovian-Gzhelian stage boundary (first appearance of Idiognathodus simulator ) is supported, while possible event markers for the Moscovian-Kasimovian boundary await further evaluation.

The evolutionary history of shell geometry in Paleozoic ammonoids

Abstract Tracking the geometry of all 597 ammonoid genera from the Lower Devonian into the Lower Triassic, a 145-Myr period that spans three mass extinctions, shows that Paleozoic ammonoid shell geometries were strongly biased for a few combinations of whorl expansion (W), whorl overlap (D), and whorl shape (S). Just three modal combinations accommodated approximately 432 genera (72% of total) and just one combination accommodated 239 genera (40%). All three primary modal forms have similar low expansion rates (W ≈ 1.75) and differ only in coiling tightness (D). These geometries resulted in long body chambers (≈400°) with Nautilus-like static in-life aperture orientations (≈30°) for the great majority (>80%) of Paleozoic ammonoids. The ancestral clade Agoniatitida included a unique spectrum of openly coiled geometries that went extinct at the Frasnian/Famennian boundary (and were not seen again until the Triassic). The Devonian/Mississippian extinction terminated the brief, explosive radiation of the Clymeniida (64 genera). The dominant Paleozoic clade, the Goniatitida (ca. 130 Myr, 374 genera [64% of total]), survived both the F/F and D/M extinctions, but began declining well before the Permian/Triassic crisis. The long-lived Prolecanitida (40 genera [7%]) appeared shortly after the D/M extinction, persisted as a low-diversity clade through the Carboniferous, and gave rise to the Ceratitida in the mid-Permian, from which were derived all Mesozoic ammonoids. After each major extinction event the phylogenetic composition of ammonoid stocks was fundamentally reordered and geometries were recanalized. Without external disturbances, as the relatively uninterrupted Mississippian through Permian record shows, the history of ammonoid shell geometry would probably have been a record of much greater constancy, perhaps tied much more closely to the Lower Devonian geometric landscape.

Morphologic and taxonomic history of Paleozoic ammonoids in time and morphospace

Abstract Principal components analysis (PCA) of 21 shell parameters (geometry, sculpture, aperture shape, and suture complexity) in 597 L. Devonian to L. Triassic ammonoid genera (spanning ∼166 Myr) shows that eight basic morphotypes appeared within ∼20 Myr of the first appearance of ammonoids. With one exception, these morphotypes persisted throughout the Paleozoic, occurring in ∼75% of the ∼5-Myr time bins used in this study. Morphotypes were not exclusive to particular lineages. Their persistence was not just a product of phylogenetic constraints or longevity, and multiple iterations of the same morphotypes occurred at different times and in different groups. Although mass extinction events severely condensed the range of morphologic variation and taxonomic diversity, the effects were short lived and most extinct morphotypes were usually iterated within 5 Myr. The most important effect of mass extinctions on ammonoid evolutionary history seems to have been their role in large scale taxonomic turnovers; they effectively eliminated previously dominant orders at the Frasnian/Famennian (F/F) (Agoniatitida), the Devonian/Mississippian (D/M) (Clymeniida), and the Permian/Triassic (P/T) (Goniatitida and Prolecanitida) extinctions. Survivors varied from two (P/T) to four (D/M) and five genera (F/F). These events generated sharp reductions in morphologic disparity at the D/M (58%) and at the P/T (59%), but there was a net increase at the F/F (38%). There was no obvious survival bias for particular morphotypes, but 64% are interpreted to have been Nautilus-like nektobenthic. The recurrence of particular combinations of morphology and their strong independence of phylogeny are strong arguments for functional constraint. Intervals between mass extinctions seem to have been relatively static in terms of morphotype numbers, in contrast to numbers of genera. Significant decreases in genus diversity (54%) and morphologic disparity (33%) commenced in the mid-Permian (Wordian/ Capitanian boundary), well before the final P/T event.

THE MIDDLE DEVONIAN (GIVETIAN) AMMONOID PHARCICERAS FROM THE NEW ALBANY SHALE, KENTUCKY

PHARCICERAS Hyatt, 1884 is the diagnostic ammonoid of the late middle Givetian Stage of the Middle Devonian Series. It occurs in the Rhenish Massif in Germany, the Montagne Noire in southern France, and in equivalent strata in the Anti-Atlas in southern Morocco. Verified North American occurrences of Pharciceras are confined to the New York succession, where the appearance of the ancestral species P. amplexum (Hall, 1886) in the Upper Tully Limestone represents an important and well-established biostratigraphic datum within the Taghanic onlap interval (see Aboussalam and Becker, 2001 for discussion). In this note we describe a second, distinctly younger, North American species, Pharciceras barnetti n. sp., from the New Albany Shale in east-central Kentucky that provides new evidence on the Taghanic onlap interval (Upper Tully/Geneseo Sequence of Baird and Brett, 2003) in the central Appalachian Basin. This occurrence is particularly significant because of its association with conodonts that provide a basis for refined correlations between the central Appalachian Basin and the Taghanic onlap succession in New York. Representatives of Pharciceras barnetti n. sp. were recovered from the Trousdale Member of the New Albany Shale at the J. K. Smith Power Plant, 3.7 km (2.3 mi) west of Trapp, Clark County, Kentucky. Here, the Trousdale sequence consists of 2.4 m of massive, platy black shale that disconformably overlies thinly interbedded argillaceous dololutites and black dolomitic shales of the Portwood Member of the New Albany Shale and is unconformably overlain by interbedded black and greenish gray shales of the Camp Run Member of the New Albany Shale (see Brett et al., 2004 for a sequence stratigraphic analysis of the Portwood and Trousdale members in central Kentucky). Ammonoids occur singly and in thin, 1–3 cm thick, pyritic chert lenses in the lower half of the Trousdale, 1.4–1.9 m above the top …

A new prodromitid ammonoid genus from the Hannibal Shale (Lower Mississippian) of Missouri

The woodbridge Clay Member of the Raritan Formation of New Jersey yields the oldest marine fauna known from the Upper Cretaceous of the United States Atlantic seaboard. This fauna is dominated by bivalves and gastropods (Richards, 1943; Stephenson, 1954), which have sufficient elements in common with the Cenomanian Woodbine Formation of Texas to suggest a Cenomanian age (Stephenson, 1954, p. 26), and this has been supported by data from megascopic plant remains and pollen (see review in Christopher, 1977; Doyle and Robbins, 1977, and references therein). The discovery, by N. F. Sohl, of two ammonite fragments in the Woodbridge Clay Member provides the first evidence for the assignment of the member within the Cenomanian Stage. The specimens came from sideritic concretions in the Woodbridge Member at the claypit of the Sayreville-Fisher Brick Company at Sayreville, Middlesex County, New Jersey (USGS Mesozoic locality 29584). General descriptions of the Raritan succession are given in Owens and Sohl (1969), Owens et al. (1977), and Owens (1983).

THE UPPER PENNSYLVANIAN (MISSOURIAN) AMMONOID PENNOCERAS FROM THE NORTH AMERICAN MIDCONTINENT

Until recently considered a rare Appalachian Basin endemic, Pennoceras Miller and Unklesbay, 1942 has emerged as one of the most widespread and locally abundant ammonoids in the lower Missourian of the Midcontinent (Boardman et al., 1994). Here we document the first Midcontinent record of the type species of Pennoceras , P. seamani Miller and Unklesbay, 1942, from the Hushpuckney Shale equivalent in southeastern Kansas. Additional, previously undescribed species of Pennoceras from the Exline Limestone and Mound City Shale equivalents in Oklahoma and southeastern Kansas are described as Pennoceras bennisoni new species and Pennoceras heckeli new species. Discovery of these ancestral species provides clarification on the derivation and early history of Pennoceras and provides a possible link to the Desmoinesian Wiedeyoceratidae. Dimensions D, H, W, and U represent conch diameter, corresponding whorl height and width, and umbilical diameter measured from seam to seam. Suture terminology is that of Ruzhencev (1960); V, L, U, I, and D represent the ventral lobe, lateral lobe, umbilical lobe, internal lateral lobe, and dorsal lobe. Sutural symbols hs, hl, and wl refer to height of secondary ventral saddle and height and width of entire ventral lobe, respectively. Repository abbreviations are: SUI, University of Iowa; CM, Carnegie Museum of Natural History. ### Type species Pennoceras seamani Miller and Unklesbay, 1942. ### Included species Pennoceras bennisoni n. sp.; Pennoceras heckeli n. sp. ### Emended diagnosis Conch small (30–35 mm at maturity), subglobose to globose (W/D 0.55–0.9) with depressed to equidimensional whorls (H/W 0.6–1.0) and closed umbilicus. Fine to coarse, straight transverse lamellae trace a low ventral salient. External suture comprises wide ventral lobe with low median saddle ( hs / hl about 0.4) and short, rounded or bluntly pointed ventral prongs; broadly rounded lateral saddle; symmetrical, narrowly rounded or bluntly pointed lateral lobe; and small, rounded umbilical lobe. Sutural formula: ( V1V1 ) …

MISSISSIPPIAN (EARLY OSAGEAN) CAVE RUN LAKE AMMONOID FAUNA, BORDEN FORMATION, NORTHEASTERN KENTUCKY

Abstract The Mississippian ammonoids Kazakhstania mangeri new species, Muensteroceras cf. oweni (Hall, 1860), and Masonoceras kentuckiense Work and Manger, 2002 occur near the base of the Nancy Member of the Borden Formation in northeastern Kentucky. Associated conodonts indicate an early Osagean [Fern Glen or lower Burlington (Dolbee Creek Member) equivalent] age corresponding to the lower Ivorian Stage of the Belgian upper Tournaisian succession.

MISSISSIPPIAN (LATE OSAGEAN) AMMONOIDS FROM THE NEW PROVIDENCE SHALE MEMBER OF THE BORDEN FORMATION, NORTH-CENTRAL KENTUCKY

Abstract The Mississippian ammonoids Polaricyclus conkini new species, P. ballardensis (Gordon, 1965), Winchelloceras knappi new species, and Cantabricanites? greenei (S. A. Miller, 1892) occur with Gnathodus texanus Zone conodonts near the base of the New Providence Shale Member of the Borden Formation in north-central Kentucky. Both ammonoids and conodonts indicate an early late Osagean (lower Keokuk equivalent) age corresponding to the middle or, more probably, the late Chadian (latest Tournaisian or early Viséan) portion of the Fascipericyclus–Ammonellipsites Zone.

Pennsylvanian (Atokan) Ammonoids from the Magoffin Member of the Four Corners Formation, Eastern Kentucky

Abstract The Pennsylvanian ammonoids Gastrioceras magoffinense n. sp., Maximites nassichuki n. sp., Dimorphoceratoides adamsi n. sp., Bisatoceras? sp., Phaneroceras chesnuti n. sp., and Christioceratidae gen. indet. occur in the Magoffin Member of the Four Corners Formation in eastern Kentucky. The interval represented by the Magoffin ammonoid fauna should be known as the Gastrioceras magoffinense Assemblage Zone. This overlies the well-known Diaboloceras neumeieri Zone, represented in the Kendrick Shale Member of the Hyden Formation in eastern Kentucky. The Gastrioceras magoffinense Zone correlates to the Diaboloceras varicostatum–Winslowoceras henbesti Zone in the Winslow Member of the Atoka Formation in northwestern Arkansas. Ammonoids and associated conodonts, including Declinognathodus marginodosus and its descendant D. donetzianus, indicate an early Atokan age corresponding to the basal Bolsovian (basal Westphalian C) Substage in western Europe and the Bashkirian–Moscovian Stage boundary interval in eastern Europe and the South Urals.

MASONOCERAS, A NEW KARAGANDOCERATID AMMONOID FROM THE LOWER MISSISSIPPIAN (LOWER OSAGEAN) OF KENTUCKY

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 Vohringer, 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 Weyers phylogenetic interpretation and makes formal description of this terminal karagandoceratid taxon (herein designated Masonoceras new genus) possible.