At human scale, 25 years seems time enough to relate academic and scientific experiences. The particular experiences presented in this book are based, first of all, on the earliest works and research at Las Hoyas led by Prof. José Luis Sanz. This book honors him as a tribute to those early years of Las Hoyas, where, while admiring the beauty of its fossils, we all learned the huge diversity of Nature and, at the same time, how to handle a number of enthusiastic students, manage the collection, and ask for funds year after year. The best of what we have all learnt from Prof. Sanz is the importance of a work that is properly done, and this sort of obsession will hound us forever.

Much or little was made in these 25 years, depending on how one looks at it. Either way, this synthesis volume aims to convey the story of our experience in the study of Las Hoyas. The present book is aimed to both specialists and informed aficionados. It incorporates many international researchers who have largely contributed to the understanding of the palaeobiology and taphonomy of this locality. The volume is organized into four major parts. Part I is devoted to the Las Hoyas environment by providing the geological framework to understand how the interpretation of this fossil Lagerstätte has changed from a deep lake at first to the current hypo­thesis of a shallow aquatic environment made of a mosaic of pools, filled by microbial mats, in a wetland-like landscape. Part II unfolds the palaeobiology of the different groups of plants and animals recorded at Las Hoyas by providing an updated revision of their taxonomic diversity. The information provided for each group is presented in a homogeneous manner by developing a summarized description of the specimens, their life styles and ecomorphology, phylogenetic context, preservation, and relevance of the Las Hoyas record within a worldwide or European frame. The processes involved in the fossil preservation are explored in Part III. This part includes not only the study of the preservation of the fossils themselves, but also some chapters devoted to experimental taphonomy and the role of microbial mats in preservation. Part IV incorporates our experience in the fieldwork in establishing how palaeoecological restorations need of a previous taphonomic study. The final chapter presents restorations by some brilliant young artists of the landscape and organisms living in the Las Hoyas Wetland during the Early Cretaceous in the framework of their trophic network. An Addendum incorporates taxa discovered or described during the elaboration of the present volume, and a final Appendix presents an updated taxonomic classification of the biota from Las Hoyas.

We wish to emphasize the idea that Las Hoyas is a laboratory of Natural History where new questions are continuously emerging: How was the site generated? What conditions were present, resulting on such abundance and exceptional preservation? What were the modes of life of those extinct organisms? What relevance has it all from an evolutionary point of view? Knowledge of the past does not always involve explaining the future, but sets the way in which it originated and shaped the present. Fossils will always be the key to unveil the History of Life on Earth.

Contributors (authors) 6-7
Acknowledgements 8
Preface: a bit of history (Francisco José Poyato-Ariza and Ángela D. Buscalioni) 9-12
I Introduction
I.1 Relevance of Las Hoyas as a Mesozoic Lagerstätte (Ángela D. Buscalioni and Francisco José Poyato-Ariza) 13
I.2 Environmental reconstruction: a historical review (Marian Fregenal-Martínez and Nieves Meléndez) 14-28
II Fossil Record
II.1 Las Hoyas in the Tree of Life (Francisco José Poyato-Ariza, Hugo Martín-Abad and Guillermo Navalón-Fernández) 29-30
II.2 Palynomorphs (Montserrat de la Fuente and Reinhard Zetter) 31-42
II.3 Plants and their landscapes (Carles Martín-Closas, Bernard Gomez and Véronique Daviero-Gomez) 43-56
II.4 Mollusca (Graciela Delvene and Martin Clive Munt) 57-63
II.5 Arachnida (Paul A. Selden) 64-67
II.6 Diplopoda (Paul A. Selden and William A. Shear) 68-69
II.7 Insecta (Xavier Delclòs and Carmen Soriano) 70-88
II.8 Ostracoda (Julio Rodríguez-Lázaro) 89-93
II.9 Spelaeogriphacea (Damiá Jaume, Eva Pinardo-Moya and Geoff A. Boxshall) 94-97
II.10 Decapoda (Alessandro Garassino) 98-102
II.11 Chondrichthyes (Rodrigo Soler-Gijón, Francisco José Poyato-Ariza, John G. Maisey and Jennifer A. Lane) 103-113
II.12 Osteichthyan fishes (Francisco José Poyato-Ariza and Hugo Martín-Abad) 114-132
II.13 Albanerpetontidae (Susan E. Evans) 133-137
II.14 Urodela (Susan E. Evans) 138-142
II.15 Salientia (Ana María Báez) 143-150
II.16 Chelonia (Adán Pérez-García, Marcelo S. de la Fuente and Francisco Ortega) 151-155
II.17 Squamata (Susan E. Evans and Arnau Bolet) 156-161
II.18 Crocodylomorpha (Angela D. Buscalioni and Beatriz Chamero) 162-169
II.19 Pterosauria (Romain Vullo and Jesús Marugán-Lobón) 170-174
II.20a Dinosauria (Ornithischia) (Mercedes Llandres Serrano, Romain Vullo and Francisco Ortega) 175-176
II.20b Dinosauria (non-avian Saurischia) (Fernando Escaso, Francisco Ortega and José Luis Sanz) 177-182
II.21 Aves (José Luis Sanz, Beatriz Chamero, Luis M. Chiappe, Jesús Marugán-Lobón, Jingmai K. O’Connor, Francisco Ortega and Fernando Escaso) 183-189
II.22 Feathers (Jesús Marugán-Lobón and Romain Vullo) 190-194
II.23 Ichnoassemblage (trace fossils) (Jordi M. de Gibert, José J. Moratalla, M. Gabriela Mángano and Luis A. Buatois) 195-201
III Taphonomy
III.1 Biostratinomic factors involved in fish preservation (Hugo Martín-Abad and Francisco José Poyato-Ariza) 202-210
III.2 Anuran biostratinomy (Álvaro López-García, Hugo Martín-Abad and Óscar Cambra-Moo) 211-215
III.3 Molecular preservation (Derek E. G. Briggs, Neal S. Gupta and Óscar Cambra-Moo) 216-219
III.4 Microbial mats and preservation (María del Carmen Guerrero, Ana Isabel López-Archilla and Miguel Iniesto) 220-228
III.5 Exceptional preservation (Francisco José Poyato-Ariza and Ángela D. Buscalioni) 229-231
IV Palaeoecology
IV.1From Taphonomy to Palaeoecology (Angela D. Buscalioni and Francisco José Poyato-Ariza) 232-237
IV.2The wetland of Las Hoyas (Ángela D. Buscalioni, Francisco José Poyato-Ariza, Jesús Marugán-Lobón, Marian Fregenal-Martínez, Óscar Sanisidro, Guillermo Navalón and Carlos de Miguel) 238-253
Addendum 1: New taxa and some latest findings (compiled by the editors) 254-257
Addendum 2: Spinolestes (compiled by the editors) 256
Appendix: Systematic list 258-259
Added in proof 260-261

Dr. Ana María BÁEZ
Paleontología Evolutiva de Vertebrados, Departamento de Ciencias Geológicas,
Universidad de Buenos Aires, Buenos Aires, Argentina

Dr. Arnau BOLET
Institut Català de Paleontología, Universitat Autònoma de Barcelona, Spain

Dr. Geoff A. BOXSHALL
Department of Palaeontology, The Natural History Museum, London, UK

Dr. Derek E. G. BRIGGS
Department of Geology and Geophysics, and Peabody Museum of Natural History,
Yale University, New Haven, Connecticut, USA

Dr. Luis A. BUATOIS
Department of Geological Sciences, University of Saskatchewan, Saskatoon, Canada

Dr. Ángela D. BUSCALIONI
Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Spain

Dr. Óscar CAMBRA MOO
Laboratorio de Poblaciones del Pasado (LAPP), Departamento de Biología,
Universidad Autónoma de Madrid, Spain

Dr. Beatriz CHAMERO
Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Spain

Dr. Luis M. CHIAPPE
The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA

Dr. Véronique DAVIERO-GOMEZ
CNRS-UMR 5276 and Université Lyon 1 (Claude Bernard), Campus de La Doua, Villeurbanne, France

Dr. Xavier DELCLÒS
Departament de Dinàmica de la Terra i de l’Oceà, Facultat de Ciències de la Terra,
Universitat de Barcelona, Spain

Dr. Graciela DELVENE
Museo Geominero, Instituto Geológico y Minero de España, Madrid, Spain

Dr. Fernando ESCASO
Grupo de Biología, Facultad de Ciencias, Universidad Nacional de Educación a Distancia, Madrid, Spain

Dr. Susan E. EVANS
Research Department of Cell and Developmental Biology, University College, London, UK

Dr. Marian FREGENAL MARTÍNEZ
Departamento de Estratigrafía. Facultad de Ciencias Geológicas & Instituto de Geociencias (UCM-CSIC),
Universidad Complutense de Madrid, Spain

Dr. Marcelo S. de la FUENTE
Departamento de Paleontología, Museo de Historia Natural de San Rafael, San Rafael, Mendoza, Argentina

Montserrat de la FUENTE
Seksjon for Naturhistorie, Vitenskapsmuseet, Norges Teknisk-Naturvitenskapelige Universitet (NTNU). Trondheim, Norge

Dr. Alessandro GARASSINO
Department of Invertebrate Paleontology, Natural History Museum, Milano, Italy

Dr. Jordi M. de GIBERT†
Departament d’Estratigrafia, Paleontologia i Geociències Marines, Universitat de Barcelona, Spain

Dr. Bernard GOMEZ
CNRS-UMR 5276 and Université Lyon 1 (Claude Bernard), Campus de La Doua, Villeurbanne, France

Dr. Neal S. GUPTA
CEdR/academic, Roslindale, Boston, MA, USA.

Dr. Maria del Carmen GUERRERO
Departamento de Ecología, Laboratorio de Ecología Microbiana, Universidad Autónoma de Madrid, Spain

Dr. Miguel INIESTO
Departamento de Ecología, Laboratorio de Ecología Microbiana, Universidad Autónoma de Madrid, Spain

Dr. Damià JAUME
Instituto Mediterráneo de Estudios Avanzados, CSIC, Universitat de les Illes Balears, Esporles, Illes Balears, Spain

Dr. Jennifer A. LANE
Bayerische Staatssammlung für Paläontologie und Geologie, Munich, Germany

Mercedes LLANDRÉS SERRANO
Museo de las Ciencias de Castilla-La Mancha, Cuenca, Spain

Dr. Ana Isabel LÓPEZ ARCHILLA
Departamento de Ecología, Laboratorio de Ecología Microbiana, Universidad Autónoma de Madrid, Spain

Álvaro LÓPEZ GARCÍA
Departamento de Biología, Universidad Autónoma de Madrid, Spain

Dr. John G. MAISEY
Department of Vertebrate Paleontology, American Museum of Natural History, New York, USA

Dr. M. Gabriela MÁNGANO
Department of Geological Sciences, University of Saskatchewan, Saskatoon, Canada

Dr. Hugo MARTÍN ABAD
Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Spain

Dr. Carles MARTÍN CLOSAS
Department d’Estratigrafia, Paleontologia i Geociències Marines, Facultat de Geologia, Universitat de Barcelona, Spain

Dr. Jesús MARUGÁN LOBÓN
Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Spain

Dr. Nieves MELÉNDEZ
Departamento de Estratigrafía. Facultad de Ciencias Geológicas & Instituto de Geociencias (UCM-CSIC),
Universidad Complutense de Madrid, Spain

Carlos de MIGUEL
Departamento de Biología, Universidad Autónoma de Madrid, Spain

Dr. José J. MORATALLA
Museo Geominero, Instituto Geológico y Minero de España, CSIC, Madrid, Spain

Dr. Martin Clive MUNT
Department of Palaeontology, The Natural History Museum, London, UK

Guillermo NAVALÓN FERNÁNDEZ
Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Spain

Dr. Jingmai K. O’CONNOR
Key Laboratory of Evolutionary Systematics of Vertebrates,
Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, People’s Republic of China

Dr. Francisco ORTEGA
Grupo de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional de Educación a Distancia, Madrid, Spain

Dr. Adán PÉREZ GARCÍA
Grupo de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional de Educación a Distancia, Madrid, Spain

Eva PINARDO MOYA
Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Spain

Dr. Francisco José POYATO ARIZA
Departamento de Biología, Universidad Autónoma de Madrid, Spain

Dr. Julio RODRÍGUEZ LÁZARO
Departamento de Estratigrafía y Paleontología, Facultad de Ciencia y Tecnología, Universidad del País Vasco, Bilbao, Spain

Dr. Óscar SANISIDRO
Departamento de Paleobiología, Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain

Dr. José Luis SANZ
Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Spain

Dr. Paul A. SELDEN
Paleontological Institute and Department of Geology, University of Kansas, Lawrence, Kansas, USA &
The Natural History Museum, London, UK

Dr. William A. SHEAR
Department of Biology, Hampden-Sydney College, Hampden-Sydney, Virginia, USA

Dr. Rodrigo SOLER GIJÓN
Museum für Naturkunde, Humboldt University, Berlin, Germany & Departamento de Paleontología,
Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, Spain

Dr. Carmen SORIANO
ESRF (European Synchrotron Radiation Facility), Grenoble, France

Dr. Romain VULLO
Laboratoire de Paléontologie, Géosciences, UMR CNRS 6118, Université de Rennes 1, Rennes, France

Dr. Reinhard ZETTER
Abteilung Paläobotanik, Institut für Paläontologie, Universität Wien, Vienna, Austria