Oneota Conodonts

Recently discovered Conodonts in the Oneota formation of Iowa are illustrated and their stratigraphic significance is discussed

Conodont Zonation of the Early Upper Devonian in Eastern Iowa

The type section of the Sweetland Creek Shale in Muscatine County has yielded a sequence of five distinct conodont faunas which correspond almost exactly to a zonation of the Upper Devonian Frasnian Stage by Ziegler (1962 b) in the Rhineland. In addition, the nearby Campbell\u27s Run section has produced the lower three faunas. The Sweetland Creek is equivalent in part to the Independence Formation, and is regarded as representing the southeastern extension of that unit in its true stratigraphic position above the Cedar Valley Formation

Type Kinderhook Ammonoids

Lower Mississippian rocks in the type area of North America have produced only a few scattered ammonoid cephalopods. Those specimens from southeastern Iowa and northwestern Missouri lie within the general vicinity of the designated type locality, near Kinderhook, Illinois. In this area, age relationships for strata near the Devonian-Mississippian boundary have been established largely through studies of their conodont faunas. However, some of the ammonoids from within the Kinderhook and adjacent beds are critical for long-range correlation. Although most of these ammonoid occurrences have been recorded, minor changes in correlation can be suggested by reexamination of the specimens, together with a review of the physical stratigraphy and the associated conodont faunal data. The Kinderhookian Wassonville Member of the Hampton Formation in southeastern Iowa and the Chouteau Limestone of Missouri fall within the lower Pericyclus-Stufe of the upper Tournaisian Stage as these units are designated for the early Lower Carboniferous of Western Europe. The index genus is present, but relatively rare in North America; associated ammonoids include Gattendorfia, Prodromites and Imitoceras. All of these genera are known from the type Kinderhook area. The same genera, plus Muensteroceras and Beyrichoceras appear to characterize the overlying Osagean beds. The directly underlying Upper Devonian also contains Imitoceras, but Cymaclymenia and Cyrtoclymenia in addition

Permian Ammonoids from Southernmost Mexico

Representatives of the ammonoid genera Perrinites and Peritrochia are described from south of Chiocomuselo, Chiapas. It is concluded that the containing beds belong in the Leonard series

Permian Ammonoids from Greenland

Danish expeditions under the leadership of Lauge Koch have collected several ammonoids from the Martinia beds of Clavering Island, northeastern Greenland. The genus Cyclolobus, which is well represented, indicates that the fauna is younger than any other Paleozoic ammonoids known from the Western Hemisphere. The containing beds are assigned to the uppermost Permian and correlated with the upper Products limestone of the Salt Range in India

Faunal studies of the type Chesteran, Upper Mississippian of southwestern Illinois

48 p., 7 pl., 4 fig.http://paleo.ku.edu/contributions.htm

Stenolobulites n. gen., Early Permian ancestor of predominantly Late Permian Paragastrioceratid subfamily Pseudogastrioceratinae

20 p., 10 fig.http://paleo.ku.edu/contributions.htm

Historic Pennsylvanian Ammonoids From Iowa

The Pennsylvanian goniatite species Wiedeyoceras sanctijohanis (Wiedey) was described in 1929 on the basis of two specimens from Greene County, Iowa, collected by O. H. St. John about 1865. An additional lot of specimens representing this species has been secured from a locality only about four miles northwest of the original site. The new material serves to give a better understanding of this fossil and a basis for comparison with comparable specimens from Missouri and elsewhere

Permian Ammonoid Zones

Ammonoids are among the best of index fossils and are particularly useful for intercontinental correlations. Five major ammonoid zones are recognized in the Permian, all of which are of world-wide significance. In Texas and northern Mexico the Permian is particularly well developed and is abundantly fossiliferous, and the section in this area serves well as a standard for the rest of the world

A Laboratory Investigation of Supersonic Clumpy Flows: Experimental Design and Theoretical Analysis

We present a design for high energy density laboratory experiments studying the interaction of hypersonic shocks with a large number of inhomogeneities. These ``clumpy'' flows are relevant to a wide variety of astrophysical environments including the evolution of molecular clouds, outflows from young stars, Planetary Nebulae and Active Galactic Nuclei. The experiment consists of a strong shock (driven by a pulsed power machine or a high intensity laser) impinging on a region of randomly placed plastic rods. We discuss the goals of the specific design and how they are met by specific choices of target components. An adaptive mesh refinement hydrodynamic code is used to analyze the design and establish a predictive baseline for the experiments. The simulations confirm the effectiveness of the design in terms of articulating the differences between shocks propagating through smooth and clumpy environments. In particular, we find significant differences between the shock propagation speeds in a clumpy medium compared to a smooth one with the same average density. The simulation results are of general interest for foams in both inertial confinement fusion and laboratory astrophysics studies. Our results highlight the danger of using average properties of inhomogeneous astrophysical environments when comparing timescales for critical processes such as shock crossing and gravitational collapse times.Comment: 7 pages, 6 figures. Submitted to the Astrophysical Journal. For additional information, including simulation animations and the pdf and ps files of the paper with embedded high-quality images, see http://pas.rochester.edu/~wm