زمین شناس

The Conodonta: Morphology, Taxonomy, Paleoecology, and Evolutionary History of a Long-Extinct Animal Phylum (Oxford Monographs on Geology and Geophy)
By Walter C. Sweet

• Publisher:   Oxford University Press, USA
• Number Of Pages:   224
• Publication Date:   1988-10-13
• ISBN-10 / ASIN:   0195043529
• ISBN-13 / EAN:   9780195043525

Product Description:

This succinct treatise presents an up-to-date assessment on the nature and evolutionary development of a phylum of extinct marine invertebrates. Conodonts are represented by a diverse array of tiny tooth-like fossils, and are widely used in stratigraphical correlation. They are also vital in the search for petroleum because the colors of fossils brought up in drill cores indicate potential oil reservoirs. Dr. Sweet, a leading researcher in the field, presents a novel view of the evolutionary history of the Conodonta besides examining their morphology, taxonomy, and paleoecology.

PREFACE

Conodonts are common fossils. Almost anyone who deals on a regular basis with Paleozoic and Triassic marine rocks has probably seen a few of them. Through the last 30 years conodonts have come to be of exceptional value in biostratigraphy, and they now have pride of place as index fossils in many parts of the geologic column. But conodonts are extinct and are unknown to most neontologists. The sketchiness of information about them in most texts on invertebrate paleontology may result either from the fact that they are microfossils that have only lately come to be important as stratigraphic tools, or from the fact that nothing quite like them exists today, so their zoologic relations are uncertain.
In this monograph, I provide a summary of information about a group with which I have worked all my adult life. Charts that name conodont-based biozones and show stratigraphic range of selected conodont species are included as Appendix B. However, I have purposely avoided a recap of conodont biostratigraphy because it is constantly changing and current views are readily available in various other places. Instead, I focus here on the conodonts as a group of extinct animals, about which it is important to know as much as possible before assessing their distribution biostratigraphically.
Of course, one takes considerable risk in attempting such a summary, particularly of a group of animals known only from its fossil record, because most of what I think I know about conodonts as animals is either conjecture or a highly personal interpretation of a still-imperfect fossil record. So, with the caveat that what follows is only one way of viewing an important group, I offer my account of the Conodonta.
For their "witting" or unwitting contributions to what I believe I know about the fascinating group of extinct animals described on the following pages, I am grateful to a long list of my students and faculty colleagues at The Ohio State University, especially Stig M. Bergstrom, and to members of the Pander Society, an international group of exceptionally good-natured "conodontologists" that has met frequently and informally through the last 20 years to share information about conodonts, argue conclusions, and correct the misapprehensions of its senior members.
Karen Tyler, faculty illustrator at The Ohio State University, drafted nearly all the figures from my very crude copy and assisted with labeling others. Dr. Jerzy Dzik, of the Polish Academy of Sciences, Warszawa, provided about half the stippled drawings of conodonts that grace various figures in Chapter 5. The artistry of these two good friends is plainly evident in their work and is warmly acknowledged.
I am also grateful to Sue Shipley and David Little, of The Ohio State University, for their help in completing various parts of the manuscript and illustrations, and to Mark Kleffner, who graciously compiled information on the ranges of Silurian conodonts and assembled the Silurian chart in Appendix B. The Department of Geology and Mineralology generously assumed much of the expense of drafting and photography.



CONTENTS

1. Inhoduction
1.1 History ofdiscovery and study
1.2 Achievements
1.3 Pending problems
Skeletal anatomy
2.1 Composition of conodont elements
2.2 Structure of skeletal elements
2.3 Shapes of element crowns
2.3.1 Coniform crowns
2.3.2 Ramiform crowns
2.3.3 Rastrate crowns
2.3.4 Pectiniformcrowns
2.4 Symmetry- and curvature-transition series
2.5 Skeletalapparatuses
2.6 Symmetry of elements, element pairs, and apparatuses
Whole-animal anatomy
3.1 The Scottish Carboniferous specimens
3.2 The Waukesha specimen
3.3 Histology of demineralized tissues
3.4 Summary
Taxonomy
4.1 Form taxonomy
4.2 Multielementtaxonomy
4.2.1 Multielementmethodology
4.3 Multielement classifications
4.4 A revised multielement classification
5. The major conodont groups
5.1 Introduction
5.2 Cavidonti and Conodonti
5.3 The Proconodontida (Cavidonti) and its families (Fig. 5.1)
5.4 The Belodellida and its families (Fig. 5.1)
5.5 OrderProtopanderodontida, new
5.5.1 Family Protopanderodontidae Lindstrtim, 1970
5.5.2 Family Clavohamulidae Lindstrdm, 1970
5.5.3 Family Acanthodontidae Lindstritm, 1970
5.5.4 Family Drepanoistodontidae Fihraeus and Nowlan, 1978
5.6 The Panderodontida
5.6.1 Family Panderodontidae Lindstrom, 1970
5.7 The Prioniodontida Dzik, 1976
5.7.1 Family Oistodontidae Lindström, 1970
5.7.2 Family Prioniodontidae Bassler, 1925
5.7.3 Family Balognathidae Hass, 1959
5.7.4 Family Icriodellidae, new
5.7.5 Family Distomodontidae Klapper, 1981
5.7.6 Family Icriodontidae Müller and Müller, 1957
5.7.7 Family Polyplacognathidae Bergström, 1981
5.7.8 Family Multioistodontidae Harris, 1964
5.7.9 Family Plectodinidae, new
5.7.10 Family Cyrtoniodontidae Hass, 1959
5.7.11 Family Rhipidognathidae Lindström, 1970
5.7.12 Family Periodontidae Lindström, 1970
5.8 The Prioniodinida, new
5.8.1 Family Chirognathidae Branson and Mehl, 1944
5.8.2 Family Prioniodinidae Bassler, 1925
5.8.3 Family Bactrognathidae Lindström, 1970
5.8.4 Family Ellisoniidae Clark, 1972
5.8.5 Family Gondolellidae Lindström, 1970
5.9 The Ozarkodinida Dzik, 1976
5.9.1 Family Spathognathodontidae Hass, 1959
5.9.2 Family Kockelellidae Klapper, 1981
5.9.3 Family Pterospathodontidae Cooper, 1977
5.9.4 Family Polygnathidae Bassler, 1925
5.9.5 Family Palmatolepidae, new
5.9.6 Family Elictognathidae Austin and Rhodes, 1981
5.9.7 Family Gnathodontidae, new
5.9.8 Lochriea and Vogelgnathus
5.9.9 Family Idiognathodontidae Harris and Hollingswort
5.9.10 Family Anchignathodontidae Clark, 1972
5.9.11 Family Sweetognathidae Ritter, 1986
5.9.12 Family Cavusgnathidae Austin and Rhodes, 1981
5.9.13 Family Mestognathidae Austin and Rhodes, 1981
5.10 Order Unknown
5.10.1 Family Coleodontidae Branson and Mehl, 1944
6. Evolutionary patterns
6.1 Introduction
6.2 Diversity patterns
6.2.1 Overall pattern
6.2.2 Long-term cycles
6.3 Second-order cycles
6.3.1 Cycles I and II
6.3.2 Middle and Late Ordovician Cycle III
6.3.3 Silurian cycles
6.3.4 Devonian and Carboniferous cycles
6.3.5 Permian and Triassic cycles
6.4 Extinction
6.5 Iterativeevolutionarypatterns
6.6 Evolutionary trends
6.6.1 Apparatuselaboration
6.6.2 Apparatusreduction
6.6.3 Elaboration of elements in P positions
6.7 Developmentasl lralegies
6.7.1 Recapitulation
6.7.2 Paedomorphosrs
6.8 Summary
7. Paleoecologya nd paleobiogeography
7.1 Introduction
7.2 Mode of life, or habit, of conodonts
7 .3 Ecologic models
1.3.1 Thedepth-stratificationmodel
1 .3.2 The lateral-segegation model
7 .4 Selected studies of conodont ecology
7.4.1 Ordovician paleoecologyo f Cincinnati Region
7.4.2 Mississippianp aleoecologyw, esternU nited States
7.4.3 Paleoecologyo f Pennsylvanianc onodonts
7.5 Ecologicgeneralizations
7 .5.1 Depth as a factor
7.5.2 Ternperuture as a factor
7.5.3 Nearshore and ofshore faunas
7.5.4 Phyletic changes in ecological distribution
7.6 Paleobiogeography
7.6.1 Late Cambrian and Ordovician paleobiogeography
7.6.2 Later Paleozoic and Triassic paleobiogeography
8, The phylum Conodonta
8.1 A personal bias
8.2 Summary of conodont characters
8.3 Conodonts as invertebrates
8.3.1 Arthropod and annelid connections
8.3.2 Molluscanconnections
8.3.3 Connections with other invertebrates
8.4 Conodonts as chordates
8.4.1 The opinions of Pander
8.4.2 Newberry, Hinde, Huxley and Myxine
8.4.3 Macfarlane and the nemertinean connection
8.4.4 The belief of Ulrich and Bassler
8.4.5 Discovery and interpretation of basal bony material
8.4.6 Composition and growth of elements
8.4.7 Interpretations of the Scottish Carboniferous specimens
8.4.8 The lingual apparatus of Myxine
8.4.9 Summary of features indicating chordate affinities 8.5 L'Envoi
Appendix A A summary classification of the Conodonta
Appendix B Stratigraphic range charts