ECHINODERMATA - KU ScholarWorks - University of Kansas

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4 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS PLATE ILLUSTRATIONS FIGURE 1-18. Genera of the Order Fissiculata. 1-221. Schematic diagrams made from camera lucida 19-54. Genera of the Order Spiraculata. drawings, showing interpretations of morphological features of blastoids.
BLASTOID STUDIES 5 ABSTRACT In order to understand the taxonomy and phylogeny of blastoids it is necessary that all known species of blastoids be revised, with emphasis placed upon internal, anal, and oral features. In the present work only 44 genera are studied (12 new; 3 Permian, 41 Mississippian and older) because of a time limit. These are arranged alphabetically under the orders Fissiculata (exposed hydrospire slits) and Spiraculata (hidden hydrospire slits, with pores and spiracles) and no attempt is made to arrange them into natural families. Certain genera of the Fissiculata may have given rise to some of the Spiraculata independently in Europe and North America. The Mastoids of Timor, Europe, Russia, and North America have almost nothing in common. This probably reflects the need for more collecting in critical areas and the restudy of present material, but it could mean that blastoids were provincial. Genera are distinguished by a combination of characters: (1) spiracles, (2) anal deltoids and type of overlap along radiodeltoid sutures, (3) hydrospires, (4) lancet plate position, (5) pores, and (6) oral plates. In most genera the first three characters are the most important. If the Fissiculata are considered primitive, a primitive blastoid is one that is steeply conical, with 4 anal deltoids, slits exposed, radials overlapping deltoids, lancet covered by side plates, and lancet elongate, reaching almost to the oral opening. An advanced form is globular or winged or both, with 2 anal deltoids (or 1 as in Pentremites), hidden hydrospire slits that open into a spiracular slit or hydrospire canal, elongate deltoids overlapping radials, and lancet exposed, not adjacent to the oral opening or lancet short and wide. The origin of the Blastoidea is unknown. INTRODUCTION PURPOSE AND SCOPE The purpose of this work is to provide basic data for the forthcoming Treatise on Invertebrate Paleontology, and to show that the study of blastoids is in its infancy. At present there is no adequate comprehensive compilation of blastoid knowledge, and the present work is only a progress report toward that goal. The best available morphologic work is that of ETI IERIDGE & CARPENTER (1886), upon which most former treatises, textbooks, and research articles have been based. The book lacks photographs and has drawings that show only one anal deltoid in all blastoids that were studied. Also it is impossible to determine the nature of overlap along the radiodeltoid suture, the variability of internal features, the nature of the pores in the deltoid plate, the nature of the side plates, and relative covering of the lancet plate. Thus, there is need for a restudy of the Blastoidea, with emphasis on morphology, resulting in a revision of the basic principles underlying the classification of genera. The scope of this paper is to present a short description of one or more species of each genus of pre- Pennsylvanian blastoids, with attention to features previously overlooked. The type species was studied where available, but where not available, other species had to be studied. The paper is not complete, since only three Permian genera were studied. It is hoped that others will continue with similar investigations. PREVIOUS STUDIES The earliest positive references to blastoids are contained in publications by S. L. MITCHILL (1808) and J. PARKINSON (1808), both of which refer to an "Asterite" or "asterial fossil" from Kentucky, and illustrate the blastoid now called Pentremites godoni. In 1819, J. L. M. DEFRANCE named this fossil encrina Godonii, thus becoming the first to use a binomial zoological designation for a blastoid species. Until 1825, however, no one knew how to classify this echinoderm, for it obviously differed greatly from such groups as the starfishes, echinoids, and crinoids. It was THOMAS SAY, in 1825, who proposed the "family" Blastoidea, to include fossils of this nature, as distinct from other echinoderms. In 1851, the first morphologic study of the blastoids was published by C. F. ROEMER, who in this work reported the discovery of marginal pores along the ambulacra and mentioned that the folds beneath the ambulacra continue upward into openings near the mouth. In 1869, these folds were called hyprospires by E. BILLINGS. New genera and species were discovered in Europe and North America, and need arose for organizing accumulated knowledge both of the morphological features and taxonomy of these fossils. In 1886, R. ETHERIDGE & P. H. CARPENTER published a comprehensive study of the blastoids, similar to but much more exhaustive than the earlier work by ROEMER. Their paper, based on 7 years of intensive study of
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