Walter L. Manger

Preliminary account of Late Devonian palynomorph assemblages from the Bedford Shale and Berea Sandstone Formations of central Ohio, U.S.A.

Diverse assemblages of well preserved miospores and microplankton have been obtained from a series of samples collected across the boundary between the Bedford Shale and Berea Sandstone Formations in central Ohio. The miospores indicate a Late Devonian (pre-Carboniferous Tournaisian)* age for each of the samples. The microplankton support this age determination. A number of microplankton species not previously recorded from North America are present.

Mississippian (Lower Carboniferous) miospores from the Cuyahoga and Logan formations of northeastern Ohio, USA

Well-preserved Lower Mississippian (Dinantian) miospore assemblages have been recovered from the upper Cuyahoga Formation (type Wooster Member) and overlying lower Logan Formation (Byer Member) at two localities in Wayne County, northeastern Ohio, USA. All six samples were productive and yielded assemblages that represent the middle Tournaisian Spelaeotriletes pretiosus–Raistrickia clavata (PC) Miospore Biozone of Western Europe including a new species of trilete, acamerate miospore, Mooreisporites streelii, described from the Wooster Shale. Significant numbers of latest Devonian and earlier Carboniferous miospores are reworked into all assemblages. The palynological evidence is consistent with a late Kinderhookian age for most of the Cuyahoga Formation, including its well known ammonoid fauna. However, the position of the boundary between the Kinderhookian and Osagean Series remains uncertain.

The Morrowan-Atokan (Pennsylvanian) boundary problem

Recognition of the Morrowan-Atokan Series boundary of the Pennsylvanian Subsystem in North America is complicated by the presence of unconformities succeeded by poorly fossiliferous lithologies at that level in both type regions. Abandonment of the name Atokan in favor of the alternatively used name Derryan would not resolve the problem. The appearance of the fusiform fusulinid Profusulinella has been taken to mark the base of the Atokan Series since its proposal, yet there is no evidence to support that conclusion. A competing definition based on the appearance of the primitive fusulinids Pseudostqffella and Eoschubertella seems to define better a boundary that is consistent with what is known of the Morrowan and Atokan type regions and of other faunal groups. A boundary stratotype is needed to fully resolve the problem.

Pathologic Gigantism in Middle Carboniferous Cephalopods, Southern Midcontinent, United States

Giant genera and species occur in virtually every phylum of the Kingdom Animalia. For the most part, their existence has been viewed as an illustration of Cope’s Rule: the tendency toward phylogenetic size increase among groups of organisms. Giant Mesozoic ammonites are frequently cited examples of this trend, and the giants are typically treated as discrete taxonomic entities. In contrast, pathologic gigantism is a rare condition that results in abnormal growth of an individual beyond the normal size limits of its species, and does not reflect Cope’s Rule. That condition is little known among invertebrates, although pathologic gigantism has been reported in prosobranch and pulmonate gastropods, where it is associated with infestation by larval trematodes that caused parasitic castration.

Possible Cephalopod Reproductive Mass Mortality Reflected by Middle Carboniferous Assemblages, Arkansas, Southern United States

Middle Carboniferous cephalopod assemblages across northern Arkansas are dominated by a small number of ammonoid species that occur in unusual abundances. Individuals of a particular species exhibit strikingly similar size, yet both small and large species are represented. Assemblages occur in either high energy deposits of conglomeratic sandstone or oolite, or low energy concretionary, dark shales, but in neither case do they seem to have undergone post-mortem sorting. Ammonitellas and protoconchs are notably absent in the matrix preserving the ammonoids in both settings. These assemblages may represent sexually mature adults that experienced mass mortality following reproduction (semelparity) in a manner similar to that found in some modern squids.

ONTOGENY AND HETEROCHRONY IN THE MIDDLE CARBONIFEROUS AMMONOID ARKANITES RELICTUS (QUINN, McCALEB, AND WEBB) FROM NORTHERN ARKANSAS

Abstract 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.

U–Pb detrital zircon evidence of transcontinental sediment dispersal: provenance of Late Mississippian Wedington Sandstone member, NW Arkansas

ABSTRACT U–Pb ages of detrital zircons from the Wedington Sandstone member in northwest Arkansas provide evidence for Late Mississippian westward transcontinental sediment transport from the Appalachian foreland. The Late Mississippian Wedington Sandstone member of the Fayetteville Shale is a fine- to medium-grained quartzarenite. It separates the Fayetteville Shale into informal lower and upper intervals, and was deposited as a small constructive delta complex that prograded towards the south and southeast during the Late Mississippian. As a major influx of clastic sediments, the Wedington Sandstone member records the sediment source and dispersal in the mid-continent during the Late Mississippian. A total of 559 detrital zircon grains from six Wedington samples were recovered for U–Pb detrital zircon geochronological analysis. Results show that age distributions can be subdivided into six groups: ~350–500, ~900–1350, ~1360–1500, ~1600–1800, ~1800–2300, and > ~2500 Ma, and are characterized by a prominent peak for the age group of ~900–1350 Ma, a major peak at ~1600–1800 Ma, and a few other minor age clusters. Regional correlation and geological evidence from surrounding areas suggest that the transcontinental sediment dispersal started as early as the Late Mississippian. U–Pb detrital zircon age distribution suggests that the Wedington Sandstone member was likely derived from the Appalachian foreland with contributions from the Nemaha Ridge to the west where the Yavapai–Mazatzal sources were exposed during the Late Mississippian. Sediment was likely transported westward through or around the Illinois Basin, merged with mid-continent sediment, and then entered into its current location in northwest Arkansas. Transportation of this sediment from mixed sources continued along its course to the south, forming a delta on the Northern Arkansas Structural Platform.

A Deformed Marine Pisolite from the Plattsburg Limestone (Upper Pennsylvanian) of Southeastern Kansas

ABSTRACT The late Missourian Plattsburg Limestone in Wilson County, Kansas contains a well developed marine pisolite associated with a phylloid-algal mound complex. A striking feature shown by this pisolite is plastic deformation caused by compaction which preceded cementation. This deformation formed chains of pisoliths, connected by apophyses. at all angle to the bedding. Evidence suggests that the pisoliths resulted from several interrupted periods of accretion, and that various states of induration existed among and within the discrete bodies prior to lithification.

U–Pb detrital zircon geochronology and Hf isotopic composition of Permian clastic rocks, Zhen’an basin, South Qinling belt: implications for the Paleozoic tectonic evolution of the Qinling orogenic belt

ABSTRACT Detrital zircon U–Pb geochronology, and Hf isotope compositional data for Permian strata near Xikou, Zhen’an in the South Qinling belt help constrain the tectonic evolutionary history of the Qinling Orogenic Belt. Results show that detrital zircons recovered from three sandstone samples share similar age-probabilities, including four age groups comprising 2100–1760 Ma (55.8%), 2750–2300 Ma (16.1%), 1200–770 Ma (12.3%), and 512–256 Ma (10.1%). By comparison with potential source areas, we conclude that Permian detrital zircons mainly originated from the southern margin of the North China Block, and probably the North Qinling belt as well, while the northern margin of the Yangtze Block did not supply detrital sediment. This distribution implies the South Qinling belt lay adjacent to the North Qinling belt and the North China Block by the Permian, but was separated from the Yangtze Block by the Mianlue Ocean, and support the Late Triassic collision between the Yangtze and North China Blocks.

PC-Based Collections Management with GEOLABEL

GEOLABEL is a menu-driven program for collections management in paleontology, mineralogy, and petrology that can be used on any IBM or IBM compatible personal computer. It produces attractive, standardized labels from a database that is continuously updated as entries are keyed in. Catalogs of the database can be assembled and printed according to specimen number or name. Use of GEOLABEL promotes good collections management by eliminating the commonly cited problems in dealing with geological specimens.