David L. Meyer

Adaptive radiation of the comatulid crinoids

Modern crinoids are dominated by the comatulids (unstalked forms) which range from the intertidal to abyssal depths. Modern stalked crinoids are restricted to depths greater than about 100 m. In the geologic past some stalked crinoids lived at depths of a few tens of meters or less in reef and bank environments. The primary vehicles postulated for the post-Triassic radiation of comatulids are lack of permanent fixation to the substratum and the capacity for mobility. Development of complex muscular articulations has enabled crawling or swimming which serve in habitat selection and avoidance of stress and predators. These and other adaptations may have bestowed on comatulids a higher survival capacity in shallow-water environments compared to stalked crinoids. Modern stalked crinoids lack mobility and complex behavioral adaptations seen in comatulids. Possibly, stalked crinoids in shallow water were unable to cope with the radiation of abundant, predaceous bony fishes in the late Mesozoic and became restricted to greater depths while the more adaptable comatulids gained ascendancy in shallow water.

The Detection and Importance of Subtle Biofacies within a Single Lithofacies: The Upper Ordovician Kope Formation of the Cincinnati, Ohio Region

Abstract Environmental controls on the distribution of fossils most commonly are found by recognizing that certain distinctive fossil assemblages are associated with particular lithofacies. Lack of change in lithofacies commonly is used as indicating a lack of significant environmental effects on the stratigraphic distribution of fossils. The results presented here challenge that view. The Upper Ordovician Kope Formation of the Cincinnati, Ohio, area has long been considered a single unit, both lithostratigraphically and in terms of depositional environment. Gradient analysis of over 1000 fossil assemblages reveals subtle environmental control on the distribution of fossils, in the absence of obvious lithologic change. This gradient analysis is used to construct an ecological model of the Kope fauna, with values of preferred depth, depth tolerance, and peak abundance estimated for the most common fossils. This method, conducted within a single lithofacies, offers the potential for reconstructing sequence architecture because faunas can be more sensitive recorders of environment than lithofacies. In addition, the presence of subtle facies control as in the Kope raises the prospect that environmental controls on paleobiologic and biostratigraphic patterns may be more pervasive than generally acknowledged.

Evolutionary implications of predation on Recent comatulid crinoids from the Great Barrier Reef

-Diving investigations of Recent comatulid crinoids at Lizard Island, Great Barrier Reef, indicate that, contrary to long-held notions, crinoids are subject to predation, principally by fishes of several families. Predation usually occurs as sublethal damage to the visceral mass and arms, from which the crinoids usually recover by regeneration. Aspects of the life habits, morphology, biochemistry, and physiology of comatulids are postulated to be adaptations that enable comatulid crinoids to resist predation. Comatulid versatility in coping with predation may account in large measure for their evolutionary success in the face of the late Mesozoic teleost radiation. Frequency of damage and repair in fossil crinoids can be used as a measure of predation pressure in order to assess the impact of predation during the Phanerozoic evolution of crinoids. Paleozoic stalked crinoids made a heavy investment in skeletal armor, while in contrast, comatulids reduced the calyx and became mobile. The relationship between these phyletic trends and predation pressure can now be critically examined. David L. Meyer. Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221 Accepted: February 14, 1985

Biotic Interactions among Recent and among Fossil Crinoids

Most previous reports on the biotic interactions of crinoids have treated either the living or the fossil forms exclusively. Major treatments of the biotic interactions of living crinoids are those of Clark (1921), Hyman (1955), Fell (1966), and Breimer (1978). Interactions of extinct crinoids have been summarized by N. G. Lane (1978). In the present review, we have compiled evidence for biotic interactions of both living and fossil crinoids in order to elucidate the role of biotic interactions in crinoid evolution. In Sections 2 through 6, we consider direct interactions of crinoids with other organisms and other crinoids. In Section 7, Habitat Modification, we consider ways by which crinoids modify their environment which will affect other organisms. The evolutionary history of biotic interactions of crinoids provides evidence that predation and competition have played significant roles in crinoid evolution.

The Use of Faunal Gradient Analysis for Intraregional Correlation and Assessment of Changes in Sea‐Floor Topography in the Type Cincinnatian

In paleobiology and stratigraphy, there is a growing need to develop high‐resolution chronostratigraphic frameworks at regional scales, which would permit unprecedented assessments of spatiotemporal variation in preserved biotas. Here, we present an intraregional correlation for the Kope and lower Fairview Formations of the type Cincinnatian, on the basis of detrended correspondence analysis (DCA) of faunal census data; we believe that the method also holds promise as a tool of correlation in other fossiliferous venues. The data were collected directly in the field at closely spaced stratigraphic intervals but with relatively coarse taxonomic and quantitative data resolution. This approach is independent of lithologic assessments and does not require the delineation of sequence stratigraphic architecture in the study area. Faunal curves were constructed for each locality on the basis of stratigraphic changes in sample scores for DCA axis 1; the curves were smoothed to reveal a long‐term signal of paleoenvironmental change recognizable at all localities. Several inflections on the curves provided lines of correlation from locality to locality. Moreover, comparisons of sample scores among three of the localities suggested notable changes through time in the relative paleoenvironmental attributes of locations arrayed across the Cincinnatian paleoramp, indicating that the sea floor was spatiotemporally dynamic.

Cycle Anatomy and Variability in the Storm‐Dominated Type Cincinnatian (Upper Ordovician): Coming to Grips With Cycle Delineation and Genesis

Although parasequence and sequence are scale‐independent terms, they are frequently applied only to specific scales of cycles. For example, meter‐scale cycles are commonly assumed to be parasequences or PACs. In the Upper Ordovi‐cian Kope and Fairview Formations of northern Kentucky, we examined a succession of 50 meter‐scale cycles that have been variously interpreted as deepening‐upward, shallowing‐upward, or showing no relationship with water depth. Our analysis shows that these cycles, characterized by shifts in storm‐bed proximality, are highly variable in their thickness and internal construction. Most cycles are best considered high‐frequency sequences, because deepening‐upward intervals are common, and many cycles contain evidence of abrupt basinward shifts in facies as expected at sequence boundaries. A minority fit the parasequence model of shallowing‐upward cycles bounded by flooding surfaces. Larger, 20 m scale cycles are defined by systematic thickening and thinning trends of meter‐scale cycles. However, meter‐scale cycles do not display any systematic trends in cycle anatomy as a function of position within the 20 m cycles or position within the Kope and Fairview Formations. The high cycle variability and the lack of systematic stratigraphic organization with respect to longer‐term cyclicity reflect either the irregularity of relative sea‐level changes, the poor recording of sea‐level changes in this deep‐water setting, or the generation of these cycles by climate‐induced cyclicity in storm intensity. These three mechanisms would generate similar patterns at the outcrop scale, so it is not possible at the present to distinguish between them.

Comparative taphonomy of echinoderms in carbonate facies; Fort Payne Formation (Lower Mississippian) of Kentucky and Tennessee

Taphonomic analysis of more than 3000 specimens of crinoids and blastoids from 14 localities from south-central Kentucky and north-central Tennessee reveals differences in preservational style among five carbonate and associated clastic facies. Collections from each locality were sorted on the basis of a 9-point taphonomic scale ranging from fully articulated specimens with arms and column to isolated plates. Degree of skeletal articulation is used as a relative measure of burial rate and autochthony. Preservational style of a pelmatozoan assemblage is the product of both depositional processes and differential taphonomic behavior of different morphotypes. The taphonomic profile for an assemblage is strongly influenced by the preservational style of its dominant pelmatozoan taxa. Taking this taxonomic and morphologic bias into account, both autochthonous and allochthonous pelmatozoan-rich facies are recognized in the Fort Payne Formation. Carbonate facies judged to be chiefly autochthonous are 1) crinoidal packstone buildups showing a full range of preservation including articulated specimens, and 2) wackestone buildups dominated by complete calyxes lacking arms and column. Green shales associated with carbonate buildups are dominated by disarticulated specimens but include complete calyxes and arm segments, suggesting slow background deposition punctuated by periodic rapid influxes. Allochthonous carbonates include 1) sheetlike packstones dominated by complete and partial calyxes, and 2) channelform packstones dominated by disarticulated skeletal debris with occasional fully articulated crinoids. Fort Payne carbonate facies in north-central Tennessee are exclusively allochthonous, sheetlike packstones, whereas both allochthonous and autochthonous facies occur in Kentucky proximal to the Borden Front. The taphonomic character and distribution of pelmatozoan-rich facies in the Fort Payne in Kentucky and Tennessee are consistent with a progradational, basin-filling depositional model.

EOCENE CRINOIDS FROM SEYMOUR ISLAND, ANTARCTIC PENINSULA: PALEOBIOGEOGRAPHIC AND PALEOECOLOGIC IMPLICATIONS

ABSTRACr-On the basis of recent collections from the Upper Eocene La Meseta Formation of Seymour Island, Antarctic Peninsula, the morphology, systematic position, taphonomy, and paleoecology of the isocrinid Metacrinus fossilis are investigated. A new species, Notocrinus rasmusseni, is described as the first comatulid crinoid known from the Antarctic fossil record. The systematic assignment of M. fossilis is maintained. Basal abrasion of calyxes and absence of long attached columns suggest that M. fossilis might have lost most of the column in adult stages and lived directly on the substratum, supported by some arms and a few cirri, similar to comatulids. About 10 percent of M. fossilis individuals show brachial regeneration, in contrast to regeneration frequencies of 7090 percent among moder Japanese isocrinids. The anomalous occurrence of isocrinids in shallow-water facies of the La Meseta is attributed to a combination of reduced predation pressure, the presumed stalkless mode of life, and a favorable temperature regime in Antarctic surface waters prior to the onset of cooling at the close of the Eocene.

Population paleoecology and comparative taphonomy of two edrioasteroid (echinodermata) pavements: Upper ordovician of kentucky and Ohio

Two strophomenid brachiopod shell pavements bearing abundant edrioasteroid epizoans occur stratigraphically within the top 4.5 m of the Corryville Formation (Upper Ordovician, Maysvillian) in Boone County, Kentucky, and Hamilton County, Ohio. Both assemblages are dominated by Isorophus cincinnatiensis and contain Carneyella pilea and Streptaster vorticellatus as lesser constituents. Pedicle exterior valves of Rafinesquina “alternata”; are the preferred substratum for all species at both sites, but the Kentucky population occurs mainly on unabraded, articulated shells and the Ohio population occupies abraded, disarticulated shells. The Kentucky population includes a greater size range of Isorophus (at least three cohorts) than the Ohio population (at least two cohorts), suggesting a greater time span of colonization for the Kentucky site. Host shells from Kentucky have anterior‐posterior axes strongly aligned NE‐SW whereas the Ohio shells are unoriented. Isorophus in Kentucky show a preference for the ante...

CRINOID DISTRIBUTION AND FEEDING MORPHOLOGY THROUGH A DEPOSITIONAL SEQUENCE: KOPE AND FAIRVIEW FORMATIONS, UPPER ORDOVICIAN, CINCINNATI ARCH REGION

Abstract Crinoid columnals are major faunal components of interbedded shales and carbonates of the Upper Ordovician Kope to Fairview formations (Edenian-Maysvillian) of the Cincinnati Arch region. Six species can be identified on the basis of distinctive morphological characters of the columnals. Crinoid distribution was plotted from point-counted carbonate samples taken through a 68-m thick composite section of the Kope to Fairview formations in Campbell County, Kentucky. This section spans a shallowing-upward, third-order depositional sequence (C1), part of C2, and the Edenian-Maysvillian Stage boundary. The slender cladid crinoid Merocrinus occurs in the lowermost Kope below the base of this section. The slender disparids Cincinnaticrinus and Ectenocrinus occur throughout the section but are most abundant in the lower 25 m where the shale percentage is 60–90 percent. The larger, more robust disparid Iocrinus appears within the carbonate-rich Grand Avenue member of the Kope at 40–50 m, and the large, plated camerate Glyptocrinus first appears just above the Grand Avenue and becomes the dominant crinoid above the C1–C2 sequence boundary that lies just above the Kope-Fairview contact. The largest and most robust crinoid in this sequence, Anomalocrinus, occurs at the top of the Grand Avenue Member. Siliciclastic ratio and biofacies composition indicate that the occurrence of larger, more robust crinoid taxa is correlated with shallowing depth. Crinoid trophic niche differentiation is also correlated with decreasing depth and the concomitant increase in water movement caused by waves and currents. The deeper water disparids have a nonpinnulate filtration fan with low branch density and wider ambulacral grooves. The shallower water camerate Glyptocrinus has a pinnulate filtration fan with high branch density and narrower ambulacral grooves. These relationships are consistent with the predictions of aerosol filtration theory.