Calceocrinids are unique crinoids with the crown movably hinged to a recumbent stem. The crown was raised for feeding by closing the hinge and bending the proximal stem. While resting, the crown lay parallel to the stem with the hinge opened. Allometric equations for four species reflect a combination of ontogeny, adult body size, phylogeny, habitat, and functional morphology. The hinge of most adult calceocrinids is extended into ear-like projections which made the crown more stable on the seafloor. For the hinge moment versus the effective weight of the crown, positive allometry characterized taxa that lived in agitated environments, whereas isometry was adequate for quiet-water species. The adult body size provides a secondary effect on the data for crinoids from the same type of environment. Here, the initial intercepts are transposed so that larger animals functioned like smaller ones. The equations are independent of phylogenetic position. All species exhibit positive allometry of the length and number of plates in the arms. The food-gathering capacity of a crinoid is estimated by the number of food-catching tube-feet multiplied by the width of the food grooves, whereas the soft parts that must be fed are proportional to the crown volume. The ratio of food-gathering capacity to crown volume is either fixed or decreases slightly in larger crinoids. Statistical tests reveal that all species follow a single developmental pattern for these two parameters. However, some of the evolutionary changes in the arms permitted calceocrinids to retain an adequate food-gathering capacity into larger adult body sizes.

Food gathering of some adult Upper Ordovician crinoids was modeled by means of filtration theory. The arm-branching patterns of the 13 species examined range from nonpinnulate isotomous arms to uniserial and biserial arms with numerous pinnules. Most taxa are roughly equivalent with respect to ambient current velocities and the nutrient contents needed from seawater. Two species with extensively branched arms have markedly higher nutritional requirements at any one ambient current velocity. The results are somewhat correlated with environment in the form of differential current velocities, water flow patterns, and food abundance and composition. The data are generally compatible with filtration theory and the environmental distributions of many Ordovician and other Paleozoic crinoids, and they reveal that Upper Ordovician crinoids had at least partially developed the ecological patterns seen in later Paleozoic crinoids. Various morphological, physiological, and behavioral changes can be employed by crinoids to alter their nutritional balance. The size distributions of food particles that are caught by the crinoids are modeled. These food particle distributions for the Ordovician fossils resemble those of modern crinoids. Relative to the population of food items, the distributions of particles that are trapped are shifted towards larger items because the crinoid filtration nets are more efficient at catching larger particles. Crinoids with relatively open filtration nets and large food-catching tube feet are generalized and feed on a wide range of food particles of a relatively large mean size. The more specialized taxa with extensively branched arms bearing small and closely packed food-catching tube feet are restricted to a more narrow range of smaller food particles.

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M. 1988 01 15: Seriation of an original data matrix as applied to paleoecology. Lethaia, Vol. 21, pp. 79-93. Oslo. ISSN 0024-1164.Seriation of an original data matrix provides the paleoecologist with a simple and powerful tool for data manipulation. The data matrix lists the presences and absences of taxa in samples. The strategy is to generate a unidimensional sequence by rearranging the taxa and samples so that the presences are blocked along the matrix diagonal. The method is illustrated with two case studies from the Middle Devonian Hamilton Group of New York. The first represents a regressive interval and the seriation sequence summarizes the changes in fauna and samples which can be explained by falling sea level. The second example embraces a much wider range of variation. Seriation mainly recovers a first-order pattern related to depth and correlated variables. This seriation does not reveal parameters such as the nature of the substrate, turbidity, habitat stability and distance offshore. These data cannot be reduced to one dimension. In all cases, seriation yields results similar to those of cluster analysis and the first axis of multivariate ordinations frequently used by ecologists and paleoecologists. 0 Seriation, paleoecology, Deuonian, Hamilton Group, multiuariate analysir.