title: Evidence of Egg Diversity in Squamate Evolution from Cretaceous Anguimorph Embryos.
abstract: Lizards are remarkable amongst amniotes, for they display a unique mosaic of reproduction modes ranging from egg-laying to live-bearing. Within this patchwork, geckoes are believed to represent the only group to ever have produced fully calcified rigid-shelled eggs, contrasting with the ubiquitous parchment shelled-eggs observed in other lineages. However, this hypothesis relies only on observations of modern taxa and fossilised gecko-like eggshells which have never been found in association with any embryonic or parental remains. We report here the first attested fossil eggs of lizards from the Early Cretaceous of Thailand, combining hard eggshells with exquisitely preserved embryos of anguimoph (e.g. Komodo dragons, mosasaurs). These fossils shed light on an apparently rare reproduction strategy of squamates, demonstrate that the evolution of rigid-shelled eggs are not an exclusive specialization of geckoes, and suggest a high plasticity in the reproductive organs mineralizing eggshells.
authors.affiliation: European Synchrotron Radiation Facility, 71 rue des Martyrs, 38043, Grenoble, France; Evolutionary Studies Institute, University of the Witwatersrand, Wits 2050, Johannesburg, South Africa.
authors.forename: Vincent
authors.initials: V
authors.lastname: Fernandez
authors.affiliation: CNRS (Centre National de la Recherche Scientifique) UMR (Unité Mixte de Recherche) 8538, Laboratoire de Géologie de l'Ecole Normale Supérieure, 24, Rue Lhomond, 75231, Paris, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Buffetaut
authors.affiliation: Palaeontological Research and Education Centre, Mahasarakham University, Khamrieng Sub-district, Kantharawichai District, Maha Sarakham Province, 44150, Thailand.
authors.forename: Varavudh
authors.initials: V
authors.lastname: Suteethorn
authors.affiliation: Sorbonne Universités-CR2P - MNHN, CNRS, UPMC-Paris6, Muséum national d'Histoire Naturelle, 57 rue Buffon, CP 38, 75005, Paris, France.
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Rage
authors.affiliation: European Synchrotron Radiation Facility, 71 rue des Martyrs, 38043, Grenoble, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Tafforeau
authors.affiliation: Subdepartment of Development and Evolution, Department of Organismal Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18A, 752 36, Uppsala, Sweden; Department of Biomathematics, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Praha, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Kundrát
mesh_terms: D000818:Animals; D044822:Biodiversity; D001842:Bone and Bones / Q000000981:diagnostic imaging; D055669:Ecological and Environmental Phenomena; D004528:Egg Shell; D004625:Embryo, Nonmammalian; D019143:Evolution, Molecular; D008116:Lizards / Q000196:embryology* / Q000502:physiology; D010063:Ovum / Q000000981:diagnostic imaging / Q000502:physiology; D011859:Radiography; D012098:Reproduction