ASPECTS OF THE MICROVERTEBRATE FAUNA OF THE EARLY CRETACEOUS (BARREMIAN) WESSEX FORMATION OF THE ISLE OF WIGHT, SOUTHERN ENGLAND By STEVEN CHARLES SWEETMAN M.A. (Oxon.) 1980 F.G.S. A thesis submitted in partial fulfilment of the requirements for the award of the degree of Doctor of Philosophy of the University of Portsmouth School of Earth and Environmental Sciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth, PO1 3QL, U.K. April, 2007 0 Disclaimer Whilst registered for this degree, I have not registered for any other award. No part of this work has been submitted for any other academic award. 1 Acknowledgements At inception of this project there was a significant risk that the Wessex Formation would not yield a microvertebrate fauna. I would, therefore, like to express special thanks to Dave Martill (University of Portsmouth) for his initial support and for securing the research scholarship which made this study possible. I would also like to thank him for his supervision, generous support, encouragement and advice thereafter. Special thanks also to Susan Evans (UCL) for her enthusiastic help and advice on all matters relating to microvertebrates in general, and lizards in particular, and to Jerry Hooker (NHM) for everything relating to mammals; also to Brian Gasson for his support in the field and for the generous donation of many exceptional specimens from his private collection. The broad scope of this study has engendered the help, support and advice of many others and I am grateful to all. At the University of Portsmouth, I would like to thank Mike Barker for his support and advice; Bob Loveridge and Derek Weights for technical assistance; Darren Naish for many helpful discussions and access to his library; Jim Hendry for advice on matters relating to sedimentology; David Giles for advice on slope stability; Julian Mitchell and Sam Heads for help with cladistic analyses; Carmen Solana for help with translations; Mark Witton for discussions on pterosaurs; Mike Taylor for discussions on sauropods; and Roger Pulley and Tai Wilson for administrative assistance. Elsewhere, I would like to thank Paul Ensom and (in the order of the taxa with which they are particularly concerned) Alison Longbottom and Charlie Underwood; Jim Gardner and Andrew Milner; Paul Barrett, Sandra Chapman, Angela Milner, Lorna Steel and Paul Upchurch. Sasha Averianov, Percy Butler, Bill Clemens, Pam Gill, Zofia Kielan- Jaworowska and Zhe-Xi Luo. For general advice and stimulating discussions I would like to thank Mike Benton, Eric Buffetaut, Tom Kemp, Jean-Michael Mazin, and Joane Pouech. David Batten is thanked for providing editorial guidance, and the constructive criticism of anonymous 2 referees is gratefully acknowledged. Dave Brockhurst is thanked for collection of samples and access to his collection of mainland Wealden Group fossils. On the Isle of Wight, thanks to the Isle of Wight County Museum Service for their help and advice and in particular to Mike Bishop, to Steve Hutt for help in the field and with the collections, and to Martin Munt and (before his departure) Dan Pemberton for help with curatorial matters. Geoff and Barbara Phillips have generously provided facilities and access to exposures on their land. The National Trust and English Nature are also thanked for permission to collect samples. Nick Chase, Mick Green and Martin Simpson are thanked for their generous donation of specimens, access to their private collections and for assistance in the field. Keith Simmons is thanked for access to his private collection and Tom and John Winch are thanked for access to theirs and for assistance with the collection of samples from Yaverland. Thanks also to Denver Fowler for his help in the field and access to specimens. Last but by no means least, very special thanks to my wife Pru for her extreme forbearance, especially while this thesis was being written, and while the kitchen sink was being used to cleanse residues! 3 Contents Page Disclaimer 1 Acknowledgements 2 Contents 4 List of Figures and Tables 13 Aims and Objectives 26 Abstract 27 Chapter 1 Introduction to the Wessex Formation of the Isle of Wight 30 Historical Background 31 Geological and palaeoenvironmental setting 35 Macropalaeontological setting and microvertebrate fossil 38 distribution Overbank and pond/lake deposits 38 Point bar deposits and conglomerates 41 Crevasse splay and associated deposits 41 Plant debris beds 42 Introduction 42 Thickness and three dimensional geometry of the plant 43 debris beds Bed boundaries 45 Distribution within the Wessex Formation 45 Relationships between lithology and palaeontology 46 Plant debris 47 Intraformational and extrabasinal clasts 50 Concretions 51 Residue obtained after sieving 52 Genesis of the plant debris beds 53 4 Possible derivation of microfossils in the Wessex 57 Formation Chapter 2 Methods and Materials 60 Bulk screening 60 Sample collection 60 Construction of the bulk screening machine 61 Construction of the sieve 63 Bulk processing: - lithological limitations 64 Secondary processing 65 Recovery of microvertebrate remains 66 Scanning electron microscopy, photography, measurements 66 and phylogenetic analyses Limitations of research 67 Curation of specimens and samples 68 Institutional abbreviations 68 Chapter 3 Fishes of the Wessex Formation 69 Chondrichthyes 69 A manuscript published in the journal Palaeontology: - 70 A neoselachian shark from the non-marine Wessex Formation (Wealden Group: Early Cretaceous, Barremian) of the Isle of Wight, southern England. (Appendix a.) Osteichthyes 71 Chapter 4 Lepidosauria 76 Introduction 76 The utility of lizard tooth morphology in determining diversity in 77 a fragmentary microvertebrate assemblage The Wessex Formation lepidosaurian fauna 80 5 Rhynchocephalia 80 Squamata 80 Scincomorpha 81 Type 1 81 Type 2 83 Affinities 86 Type 3 86 Type 4 89 Type 5 90 Type 6 91 Type 7 92 Type 8 94 Type 9 95 Type 10 97 Type 11 99 Premaxillae of indeterminate tooth type 100 Anguimorpha 103 Concluding remarks 105 Chapter 5 Archosauria 106 Crocodylia 107 Indeterminate Atoposauridae 108 Crocodylia insertae sedis 109 Indeterminate bones and scutes 110 Pterosauria 111 IWCMS.2002.25-27 113 Discussion 113 IWCMS.2002.28 115 Affinities 116 Indeterminate Pterosauria 117 IWCMS.2002.29 117 6 Affinities 119 IWCMS.2002.30 119 Concluding remarks 120 Dinosauria 121 Introduction 121 Ornithischia 121 Ornithischia incertae sedis 122 IWCMS.2002.15-16 122 IWCMS.2002.17-20 123 IWCMS.2002.17 124 IWCMS.2002.18 125 IWCMS.2002.19 125 IWCMS.2002.20 126 Affinities 127 SMNS 51685 ` 128 Dinosauria incertae sedis 129 IWCMS.2002.21 129 Saurischia 130 Sauropoda incertae sedis 130 Affinities 131 Theropoda 132 Introduction 132 Theropoda incertae sedis 133 c.f. Richardoestesia sp. 133 Indeterminate Theropoda 135 Baryonychidae 137 Troodontidae 139 Dromaeosauridae 140 A manuscript published in the journal Cretaceous research: - 140 The first record of velociraptorine dinosaurs (Saurischia, Theropoda) from the Wealden (Early Cretaceous, Barremian) of southern England. (Appendix b.) 7 Aves 141 Wessex Formation birds 142 IWCMS.2002.31 143 IWCMS.2002.32 143 IWCMS.2002.33 144 Conclusions 145 Chapter 6 Mammalia 146 Introduction 146 A review of Wealden mammal fossils reported during the 19th 146 and 20th centuries Wessex Formation mammals: introduction 155 Order Eutriconodonta, Family Gobiconodontidae 157 A manuscript published in the journal Palaeontology: - 157 A gobiconodontid (Mammalia, Eutriconodonta) from the Early Cretaceous (Barremian) Wessex Formation of the Isle of Wight, southern England. (Appendix c.) Subclass Allotheria, Order Multituberculata 157 The phylogeny and systematics of multituberculate mammals 157 Temporal and geographic distribution of the Plagiaulacida 159 Eobaatar sp. nov. 161 Systematic palaeontology 161 Holotype 161 Referred material 161 Horizons and localities 161 Diagnosis 161 Differential diagnosis 162 Description 162 BMNH M 45557 164 8 Discussion 167 m2 forming part of SMNS 51981 and its possible association 167 with BMNH M 45482 BMNH M 45483 168 Description 168 Affinities 169 I2 forming part of SMNS 51981 172 Trechnotheria, Family Spalacotheriidae 174 A manuscript accepted for publication in the journal 175 Palaeontology, in press: - A Spalacolestine spalacotheriid (Mammalia, Trechnotheria) from the Early Cretaceous (Barremian) of southern England and its bearing on spalacotheriid evolution. Abstract. 175 Introduction 176 Geology 177 Methods 180 Systematic palaeontology 181 Derivation of name 182 Diagnosis 182 Differential diagnosis 182 Holotype 183 Paratypes 183 Horizons and localities 183 Description 183 Mandible and anterior denititon 183 Remarks 188 Lower molariforms 189 BMNH M 45562 194 BMNH M 45563 195 Upper molariforms 196 BMNH M 45480 196 BMNH M 45481 198 9 Phylogenetic analysis 200 Diversity and evolution of the Spalacotheriidae 202 Systematic position of a specimen from Porto Pinheiro, 202 Portugal Origin of Spalacolestinae and evolution and diversity of 203 Spalacotheriidae Appendix: character definitions and states used in the 208 phylogenetic analysis Data matrix 215 Order Dryolestida, Family Dryolestidae 217 Systematic palaeontology 219 Type species 219 Holotype 219 Paratype 219 Referred material 219 Horizon and locality 219 Diagnosis 219 Description 220 Discussion 226 Premolariforms and a caniine 227 BMNH M 45634 227 Affinities 229 BMNH M 45484 231 Affinities 232 BMNH M 45635 233 Affinities 235 BMNH M 45636 236 Affinities 237 BMNH M 45560 237 Affinities 238 10 Chapter