I the Taxonomy, Morphology and Distribution of Some

I THE TAXONOMY, MORPHOLOGY AND DISTRIBUTION OF SOME GENERA OF UPPER JURASSIC RHYNCHONELLIDS ALAN CHILDS, B.Sc.,F.G.S., Geology Department, Imperial College, London. 1966 2 ABSTRACT The major ~:art' of thiS study comprises a revision of the systematic palaeontology of the Up-)er Jurassic rhynchonellid faunas of north-western Europe. Thirty-five species belonging to the genera Monticlarella, Lacunosella, Rhynchonella, Thurmannella, Acanthothiris, Acanthorhynchia, Somalirhynchia, Septaliphoria and Torquirhynchia gen. nov. are described. By using serial sectioning and acetate peel techniques, the internal structures of all but the rarest species have been investigated and the majority of these are described and figured for the first time. Photomicrographs of acetate peels of the more interesting internal structures are figured and there is also a complete photographic record of the included species. New taxa include six species2 a subgenus and a genus. A study has been made of the variation shown by internal characters as exemplified by Ivanoviella alemanica. Observations on ecology and distribution are given with the specific descriptions. and separate sections are also included dealing with these asiDeots'at generic loyal. Evolutionary lineages are suggested for five of the sub- families considered. The techniques employed in this study are described and there is a brief synopsis .of previous research. The fullest possible synonymies are given for the species studied and a complete bibliography of works cited is appended. 3 TABLE OF CONTENTS ABSTRACT ACKNOWLEDGEMENTS, p. I INTRODUCTION p. 6. II ECOLOGY p. 14. III DISTRIBUTION p. 21. IV EVOLUTION p. 27. V MORPHOLOGY AND INTERNAL VARIATION p. 36. VI SYSTEMATIC ?ALIIEONTOLOGY p. 76. List of works to which reference is made .... • • p. 238. Plates p. 247. 4 ACKNOWLEDGEMENTS The writer would like to record his gratitude to the many people who have assisted him during the course of this study. He is particularly grateful to Dr.D.V. Ager who originally suggested the main topic for research and who has subsequently given much valuable advice and guidance. The writer is also indebted to those museums, universities and individuals who have loaned and donated material from their collections. These include Dr. Barthel, Bayerische Staatsammlung, Min*h; M.Delfaud, University of Bordeaux; Dr. Dreyfuss, University of Besanion; M.Snay, University of Lyon; Dr. Gidon, University of Chamb6ry; H.Panchaud and Dr. Gasche, Naturhistorisches Museum, Basel; M.Rioult, University of Caen; Dr. Schumann, University of Tilbingen; Prof. Tintant and M.Delance, University of Dijon and Dr.Zeiss, University of Erlangen. Special thanks are due to the representatives of the Societ6 Nationale des Petroles d'Aquitaine, particularly M.Capdecomme, and to M.Naubeurge for, assistance in the field in the Pyrenees and the area around Nancy respectively. With regard to loans of British material, the writer particularly wishes to thank Mr.E.F.Owen of the British Museum of Natural History; Mr.J.L. Edmonds, University Museum, Oxford; Mr.A.G. Brighton, Sedgewick Museum, Cambridge and Dr. R.D.Wilson of the Geological Survey, Edinburgh. Mr. J.A. Gee gave much advice and• assistance in photographic matters for which the author is very grateful. The author also wishes to acknowledge the usefUl discussions with his colleagues Dr.P. Copper and Pearson and he is also indebted to the latter for donating a large collection of Polish specimens. Grateful thanks are recorded to the author's wife for continual support and encouragement as well. as for 5 valuable assistance during fieldwork. Finally the writer wishes to tho..nk the Natural Environment Research Council. for the award of a Research Studentship allowing him to carry out this study. 6 INTRODUCTION Objects of Study The original intention of this study was to investigate the brachiopod faunas of the Middle and Upper Jurassic of the southern French Jura but this idea was soon abandoned in favour of restricting the study to the Upper Jurassic rhynchonellids while encompassing a much wider geographical area. It was thought that the wider geographical area gave more scope for ecological and distributional studies as well as providing a much better basis for systematic work. As it was then necessary to restrict the range of forms to be investigated, the morphologically more diverse rhynchonellids were chosen. In view of the large area and the period of time involved, it was decided impracticable to do other than contact geologists who had worked on various parts of the Upper Jurassic outcrop and follow their advice as to localities for collecting and in matters of local stratigraphy. During the summer of 1964, Normandy, a large part of the French and German Jura and part of the Swiss Jura were visited. An attempt was made to collect at least some material of as many species as possible in order to observe the associated fauna and host lithologios. This material was supplemented by museum collections for the systematic descriptions and the author visited the universities of Caen, Lyon, Chambt;ry, Dijon, Besangon, Basel, Tubingen, Munbh and Erlangen for this purpose. Arrangements were made with several of the above institutions to borrow specimens for subsequent more detailed study. It was found that one of the major disadvantages of using museum collections was the biased view given of relative abundance as a result of the enthusiasm with which rarities are preserved. During this time the author received much advice and help from the staff of these universities. Subsequent shorter collecting trips were made to '7 Sutherland, Yorkshire, the Cotswolds and Dorset in order to obtain British material. During the summer of 1965 collections were made from the French Pyrenees and the northern rim of the Paris Basin. This latter field season also included an abortive attempt to collect from the area around Lisbon and also from the area around La Rochelle (Charente Maritme). Although most of the species described have been previously figured, this is the first attempt to give a comprehensive account of these faunas and to clarify their synonymies. It is interesting to note in this connection that the French literature abounds with Orbigny and Lamarck species, the German with those of Schlotheim, Oppel and quenstedt while many British authors rely on Sowerby and Davidson. By making a palaeontological study on a wider geographical basis than is usually attempted, it is hoped to reduce the number of species confined by national boundaries. It is considered that the other major justification for attempting to study a group over a relatively wide geographical area is that in considering evolutionary lineages this helps to eliminate any local distortion caused by migration and the general imperfection of the fossil record. Although essentially work has been confined to taxa within the Upper Jurassic, certain species and genera from lower stratigraphical levels have been investigated whore this was thought necessary. The type species of Acanthorhynchia, namely A.panacanthina, from the Bajocian has thus been included and similarly a study was made of Acanthothiris srDinosa in order to determine the justification for splitting the spinose forms into separate genera. Previous Research It is only proposed to mention here those authors who have made major contributions to the study of the Upper Jurassic rhynchonellids as full synonymies are included in the systematic 8 UPPER JURASSIC ZONES AND STAGES nodiger subditus UPPER VOLGIAN fulgens giganteus gorei albani pallasioides rotunda LOWER VOLG IAN pectinatus wheatIeyensis Subplanites spp. Gravesia spp. pseudomutabilis mutabilis KIMMERIDGIAN _ cymodoce baylei pseudocordata transversarium OXFORDIAN cordatum mariae Text,-fig. 1. The nomencinturo of the Upper Jurc,ssic zones =d otages used in this study. part of this work. Although no previous author has attempted to produce a comprehensive monograph of this group of rhynchonellids, there have been numerous descriptions and figures published over the last two hundred years. As there are relatively few rhynchonellids in the British Upper Jurassic rocks, most of the works referred to arc by continental authors. Linnaeus (1767) described only one of the species discussed below, namely Acanthothiria spinosa; this species was also the subject of the first figure to which reference is made, Knorr and Walch (1769). This appears to be the only recognisable eighteenth century description of a Middle or Upper Jurassic rhynchonellid. .Of the workers of the early part of the nineteenth century, the most important were Schlotheim .(1813, 1920), Zieten (1830-33) and, to a lesser extent, Lamarck (1819). The paucity of British Upper Jurassic material meant that the Sowerbys figured only species - Torquirhynchia inconstans - here described. Fischer de Waldheim's paper of 1809 must also be mentioned as this intro- duced the genus Rhynchonella. The major nineteenth century French work was undoubtedly d'Orbigny's (1850) "Prodrome", but this lost much of its potential value through lack of illustrations. From about 1850 until the beginning of the present century several eminent palaeontologists produced many of the monographs still regarded as standard works. These writers included Davidson, who described and figured all the then known British brachiopods, Eudes-Deslongchamps, who produced numerous well illustrated papers on the brachiopod faunas of Normandy and de Loriol and Haas who produced similar comprehensive works

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