1 The evolutionary relationship between beak shape, mechanical advantage, 2 and feeding ecology in modern birds 3 4 5 Guillermo Navalón1,2,*, Jen A. Bright3,4, Jesús Marugán-Lobón2,5 & Emily J. Rayfield1 6 1. School of Earth Sciences, University of Bristol, Life Sciences Building, Bristol, UK 7 2. Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Madrid, Spain. 8 3. School of Geosciences, University of South Florida, Tampa, FL 33620, USA. 9 4. Centre for Virtualization and Applied Spatial Technologies, University of South Florida, Tampa, FL 33620, USA 10 5. Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA. 11 *Corresponding author. Email:
[email protected]. 12 13 14 Author’s contributions: GN, JAB, JML and EJR designed the project. GN conducted the analyses. 15 GN, JAB, JML and EJR co-wrote the manuscript. 16 17 Acknowledgements 18 The authors are grateful to Melissa Tallman for important insights on shape analysis. We are 19 grateful to Gavin H. Thomas and Mark N. Puttick for advice on phylogenetic comparative 20 methods. We want to thank Luis Porras, Matteo Fabbri and Francisco J. Serrano for 21 enlightening discussion on the implications of our results. We are grateful to Miriam L. 22 Zelditch and three anonymous reviewers for their valuable comments that further improved the 23 quality of this research. GN is supported by a PG Scholarship/Studentship from The Alumni 24 Foundation, University of Bristol, UK. JML is supported by the Spanish MINECO, Project 25 CGL-2013-42643. EJR and JAB were supported by BBSRC grant BB/I011668/1.