The quantification of morphology through time is a vital tool in elucidating macroevolutionary patterns. Studies of disparity require intense effort but can provide insights beyond those gained using other methodologies. Over the last several decades, studies of disparity have proliferated, often using echinoderms as a model organism. Echinoderms have been used to study the methodology of disparity analyses and potential biases as well as documenting the morphological patterns observed in clades through time. Combining morphological studies with phylogenetic analyses or other disparate data sets allows for the testing of detailed and far-reaching evolutionary hypotheses.
Computational fluid dynamics (CFD), which involves using computers to simulate fluid flow, is emerging as a powerful approach for elucidating the palaeobiology of ancient organisms. Here, Imran A. Rahman describes its applications for studying fossil echinoderms. When properly configured, CFD simulations can be used to test functional hypotheses in extinct species, informing on aspects such as feeding and stability. They also show great promise for addressing ecological questions related to the interaction between organisms and their environment. CFD has the potential to become an important tool in echinoderm palaeobiology over the coming years.
The dominant faunal elements in shallow Paleozoic oceans, echinoderms are important to understanding these marine ecosystems. Echinoderms (which include such animals as sea stars, crinoids or sea lilies, sea urchins, sand dollars, and sea cucumbers) have left a rich and, for science, extremely useful fossil record. For various reasons, they provide the ideal source for answers to the questions that will help us develop a more complete understanding of global environmental and biodiversity changes. This volume highlights the modern study of fossil echinoderms and is organized into five parts: echinoderm paleoecology, functional morphology, and paleoecology; evolutionary paleoecology; morphology for refined phylogenetic studies; innovative applications of data encoded in echinoderms; and information on new crinoid data sets.
Adaptive speciation occurs when biological interactions induce disruptive selection and the evolution of assortative mating, thus triggering the splitting of lineages. Internationally recognized authorities explain exciting developments in modeling speciation, including celebrated examples of rapid speciation by natural selection. The text is geared toward students and researchers in biology, physics, and mathematics.
The Early Palaeozoic was a critical interval in the evolution of marine life on our planet. Through a window of some 120 million years, the Cambrian Explosion, Great Ordovician Biodiversification Event, End Ordovician Extinction and the subsequent Silurian Recovery established a steep trajectory of increasing marine biodiversity that started in the Late Proterozoic and continued into the Devonian. Biogeography is a key property of virtually all organisms; their distributional ranges, mapped out on a mosaic of changing palaeogeography, have played important roles in modulating the diversity and evolution of marine life. This Memoir first introduces the content, some of the concepts involved in describing and interpreting palaeobiogeography, and the changing Early Palaeozoic geography is illustrated through a series of time slices. The subsequent 26 chapters, compiled by some 130 authors from over 20 countries, describe and analyse distributional and in many cases diversity data for all the major biotic groups plotted on current palaeogeographic maps. Nearly a quarter of a century after the publication of the ‘Green Book’ (Geological Society, London, Memoir12, edited by McKerrow and Scotese), improved stratigraphic and taxonomic data together with more accurate, digitized palaeogeographic maps, have confirmed the central role of palaeobiogeography in understanding the evolution of Early Palaeozoic ecosystems and their biotas.
THE CLASSIFICATION OF ANIMALS is Still Very much a field in which discovery and revision are continuing, even after two hundred years of study. The importance of classification in biology increases every year, because the experimental and practical fields find increasing need for accurate identification of animals and for understanding of comparative relationships. At least one outstanding biologist has opposed pubUcation of this new classification on the ground that it would be accepted as final, the classification, and would tend to make students think that all higher classification is finished. The intention of the compiler is just the opposite. Just as this classification is different in detail from all previous ones, so will future editions be still different, as we learn more about the comparative features of animals. It is anticipated that every new edition will spur students of the individual groups to propose improvements. It is therefore planned to issue corrected editions whenever appropriate. The very appearance of these subsequent editions will emphasize the growth of understanding of animal groups. Only one ostensibly complete classification of animals, living and fossil, has been published in recent years. That classification, by A. S. Pearse of Duke University, is a good one, based on the views of many specialists. Certain mechanical faults make it less usable than it should be, and the need for revision gave the original impetus to preparation of the present classification. Because Pearse did not usually indicate the source of his arrangements, he is not here cited as an authority. Nevertheless, the two classifications are basically very similar. No other single classification has been found that agrees so closely with the conclusions of the present study. It should be emphasized that, within certain limits, this classification is not a simple compilation of the views of specific workers. In nearly all details, choices have been made between conflicting schemes of various authors, not on the basis of the reputation of those authors but on my judgment of the soundness of their supporting arguments or on my analysis of the data they present. In none of the larger groups has the work of any single author been accepted without modification. Several considerations have influenced the decisions embodied in this classification. First, a false picture is given by a simplified classification, because the existing diversity is one of the principal features of the animal kingdom. Therefore, no groups should be combined merely for the sake of simplicity. Second, although the previous item would seem to require coverage of the groupings at all possible levels, to show the extreme range of division and subdivision, this is not in fact possible. Not only are there many conflicting groupings at certain levels, such as of phyla or orders, but there is no practical way to show these groupings in a general classification. It is a compromise that is believed to be effective to subdivide the phyla only into classes, subclasses, and orders. Other possible groupings, such as subphyla and superorders are referred to in the notes. Third, two groups which are so distinct at any level that they cannot be described in common terms must be separated at that level. (For example, Pterobranchia and Enteropneusta; see the Notes on the Taxa.) Fourth, groups which cannot be distinguished at any particular level by the type of characters used for their neighbors must be combined at that level. (For example, the sometime classes of Nematoda...
This work weaves important strands of the paleontological literature into a coherent worldview that emphasizes the importance of understanding the geological record.
This book provides a comprehensive synthesis of the range of biological information that can be retrieved from the fossilised skeletons of echinoids. The first half consists of a detailed explanation of the functional significance of skeletal structures and the inferences to be drawn from them about the living animals. This is followed by a discussion of the important evolutionary changes that have taken place and why they may have occurred. Finally, there is a section on how echinoids relate to other echinoderm groups.
