Alma Mater Studiorum – Università di Bologna DOTTORATO DI RICERCA IN SCIENZE DELLA TERRA Ciclo XXV Settore Concorsuale di afferenza: 04/A2 Settore Scientifico disciplinare: Geo/01 Paleontological studies of Cretaceous vertebrate fossil beds in the Tataouine Basin (southern Tunisia) Presentata da: Dott.ssa Contessi Michela Coordinatore Dottorato Relatore Prof. Roberto Barbieri Prof.ssa M.Cristina Perri Correlatori: Dott. Marco Avanzini Dott. Federico Fanti Esame finale anno 2013 CONTENTS CONTENTS ABSTRACT RIASSUNTO GENERAL INTRODUCTION 1 Premise 1 Aim of the work 3 References 4 CHAPTER 1 - The “Continental Intercalaire” of Southern Tunisia: stratigraphy, paleontology and paleoecology. 7 Abstract 7 1.1. Introduction 7 1.2. Study area and stratigraphic nomenclature 9 1.3. Materials, methods and institutional abbreviations 11 1.4. Biostratigraphy and age 12 1.4.1. Douiret Formation 12 1.4.2. Aïn El Guettar and Zebbag formations 14 1.5. The Douiret Formation 14 1.5.1. Fossil vertebrate of the Douiret Formation, and their paleogeographic distributions 15 1.5.1.1. Fishes 17 1.5.1.2. Turtles 17 1.5.1.3. Crocodyliforms 19 1.5.1.4. Pterosaurs 19 1.5.1.5. Dinosaurs 20 1.6. The Aïn el Guettar Formation: Chenini Member 20 1.6.1. Fossil vertebrate of the Chenini Member 22 1.6.1.1. Fishes 22 1.7. The Aïn El Guettar Formation: Oum ed Diab Member 22 1.7.1. Fossil vertebrate of the Oum ed Diab member, and their paleogeographic distributions 23 1.7.1.1. Fishes 23 1.7.1.2. Crocodyliforms 25 1.7.1.3. Dinosaurs 27 1.7.1.3.1. Theropoda 27 1.7.1.3.2. Sauropoda 27 1.7.1.3.3. Ornithopoda 28 1.7.1.4. Microvertebrate assemblage 28 1.8. Discussion 30 1.9. Paleoecological interpretation 31 1.10. Timing of depositional events 33 1.11. Conclusions 34 Acknowledgments 37 References 38 CHAPTER 2 - Vertebrate tracksites in the Middle Jurassic – Upper Cretaceous of South Tunisia. 47 Abstract 47 2.1 Introduction 47 CONTENTS 2.2 Geological setting 48 2.3 Material and methods 50 2.4 Description of the tracksites 50 2.4.1 Beni Ghedir site 50 2.4.2 Chenini site 53 2.4.3 Ksar Ayaat site 55 2.4.4 Jebel Boulouha site 57 2.5 Discussion 59 2.6 Conclusions 61 Acknowledgments 64 References 65 CHAPTER 3 - First record of bird tracks in the late Cretaceous (Cenomanian) of Tunisia 71 Abstract 71 3.1 Introduction 71 3.2 Study area and geological setting 72 3.2.1 Sedimentology and facies analysis of the track-bearing layer 74 3.3 Methods 75 3.4 Ichnological description 76 3.5 Discussion 78 3.6 Paleoecological implications 81 3.7 Conclusions 81 Acknowledgments 82 References 83 CHAPTER 4 - First report of mammal-like tracks from the Cretaceous of North Africa (Tunisia) 89 Abstract 89 4.1 Introduction 89 4.2 Geological settings 91 4.2.1 Tracksite description 92 4.3 Material and methods 92 4.4 Systematic description 92 4.5 Discussion 94 4.5.1 Systematic discussion 94 4.5.2 Affinity of the trackmaker 95 4.6 Paleoecological implications 96 4.7 Conclusions 96 Acknowledgments 96 References 97 CHAPTER 5 – Cenomanian dinosaur tracks from Tunisia: new constraints on the paleobiogeography of the Mediterranean platforms during mid-Cretaceous 101 Abstract 101 5.1 Introduction 101 5.2 Geological settings 103 5.3 Material and methods 103 5.4 Systematic paleontology 104 5.5 Systematic discussion 104 5.6. Cretaceous dinosaurs tracks from the Mediterranean carbonate platforms 107 CONTENTS 5.6.1 Ichnofaunal correlations 108 5.6.2 Paleobiogeographical considerations 110 5.7 Conclusions 110 Acknowledgments 111 References 112 GENERAL CONCLUSIONS 117 ACKNOWLEDGMENTS 119 CURRICULUM VITAE 121 ABSTRACT Cretaceous fossil vertebrate remains from Northern Africa are known in the literature from the beginning of 1900’s, when several Lower Cretaceous beds with fragmented material of fish, turtles, crocodiles and non-avian dinosaurs were discovered. In particular, the ‘Continental Intercalaire’ deposits of the Tataouine basin of southern Tunisia preserve one of the most diverse Lower Cretaceous vertebrate fauna from Africa. This alternation of Late Jurassic – Late Cretaceous shallow-marine, littoral and non-marine deposits extends from Algeria to Egypt and provides important data for the comprehension of Mesozoic faunas end ecosystems. This research project focuses on a detailed revision of the stratigraphic distribution of mid-Cretaceous fossil beds in the Tataouine Basin, and include the description of four, newly discovered vertebrate tracksites. A detailed, basin-scale revision of the stratigraphic occurrence and lateral variability of fossil-bearing strata based on accurate sampling, description, and comparison of different faunal assemblages, indicates 1. a strong, lateral facies variability within the context of a low gradient, circalittoral to coastal-plain environment, and 2. multiple and diachronous fossil beds which include elasmobranchs, actinopterygians, sarcopterygians, turtles, crocodyliforms, pterosaurs, and non-avian dinosaurs remains. In the Tataouine region, macro- and microvertebrate remains are recovered from three distinct stratigraphic intervals: the lower Douiret Formation (Barremian), the Chenini (rare) and Oum ed Diab members of the Aïn El Guettar Formation (Albian). The Douiret Formation is characterized by mainly siliciclastic deposits in coastal environments (foreshore to coastal sabkha facies): fossils recovered from this interval are essentially representative of freshwater taxa. In addition, the Chenini sandstones, known in the literature as the richest fossil-bearing unit in southern Tunisia, are barren of fossils: fossil beds are instead referred to the overlying, Oum ed Diab Member. Four vertebrate tracksites have been discovered in the study area: the Middle Jurassic Beni Ghedir site, the late Albian Chenini site, the Cenomanian Ksar Ayaat locality and the upper Cenomanian Boulouha site. Depositional settings of each tracksite have been defined on stratigraphic and sedimentologic data, and tracks are ascribed to different ichnocoenoses in relation to their paleoenvironments. In order to have a more objective representation of the vertebrate tracks, digitalisation techniques, such as laser scanning, has been used to generate three-dimensional models of the tracks. Callovian beds exposed at the Beni Ghedir site preserve approximately 130 tridactyl footprints distributed over an area of 200 square meters, and represent the oldest evidence of a dinosaur fauna in Tunisia. The Chenini tracksite includes poorly preserved crocodilian tracks and the dinosaur ichnospecies Apulosauripus federicianus, whereas footprints assigned to a pleurodiran turtle are exposed at the Ksar Ayaat locality. The J. Boulouha tracksite presents almost 100 well-preserved tridactyl tracks referred to small-sized theropods, fossil bird tracks - ichnogenus Koreanaorins – and tracks referred to a mammalian trackmaker: these discoveries represent the first report of fossil bird and mammal from the Cretaceous of continental Africa and Tunisia respectively. The occurrence, in Tunisia, of the ichnospecies A. federicianus, originally described from the Santonian of the Apulian platform, provide additional data on the controversial framework of vertebrate faunal distribution in the mid- Cretaceous Mediterranean carbonate platforms context. In particular, data collected from the Tunisian tracksites have been compared with those of Italy and Croatia, showing important analogies in overall morphology and paleoenvironmental setting of dinosaur ichnoassociations. Data presented here suggest that similar vertebrate faunas might have inhabited “extreme” environments, such as arid carbonatic platform, supporting the hypothesized subaerial connection between the northern African margin and the Mediterranean platforms during the mid-Cretaceous. RIASSUNTO Sin dall`inizio del secolo scorso, quando i primi fossili di pesci, coccodrilli, tartarughe e dinosauri furono scoperti in nord Africa, diversi studi si sono susseguiti descrivendo i depositi giurassico-cretacei, a prevalenza continentale, che si estendono dal Marocco all’Egitto, noti successivamente in letteratura col nome di “Continental intercalaire”. In particolare, nel Bacino di Tataouine nel Sud tunisino affiora l’intera successione del “Continental intercalaire”, facendo di questa regione una località ideale per la comprensione delle faune e degli ecosistemi mesozoici. Questo progetto di ricerca si propone di fornire la prima dettagliata revisione stratigrafica dei siti fossiliferi cretacei del Bacino di Tataouine e di descrivere quattro nuovi siti a impronte fossili di vertebrati recentemente scoperti. Il campionamento, la descrizione e revisione stratigrafica dei livelli fossiliferi del Bacino di Tataouine indica una forte variazione laterale delle facies, all’interno di un contesto circa-litorale o di piana costiera. I resti di macro- e microvertebrati comprendono elasmobranchi, attinopterigi, sarcopterigi, tartarughe, croccodiliformi, pterosauri e dinosauri non-aviani e provengono da tre distinti intervalli stratigrafici: la base della Formazione di Douiret, il Membro di Chenini (rari) e quello di Oum ed Diab della Formazione Aïn el Guettar. La Formazione di Douiret è caratterizzata da depositi silicoclastici di ambiente costiero, simile alle attuali sabke, in cui l`associazione faunistica presenta una prevalenza di taxa d’acqua dolce. Le sabbie fluviali del Membro di Chenini, a cui in precedenza venivano attribuiti gli intervalli fossiliferi, sono qui considerate sterili, i resti di vertebrati sono invece interpretati come conglomerati transgressivi, marker