Earliest laurasian sauropod eggshells

摘要: Megaloolithid eggshells, known from many Cretaceous deposits since 19th century, are now recognized as remnants of sauropod dinosaurs. Our paper reports the discovery megaloolithid egg remains Middle Jurassic (Bajocian) Quercy area (southwestern France). The new ootaxon differs related oospecies in having un− usually thin shells. Even Megaloolithus aureliensis, thinnest France is three times thicker than eggshells. cladistic analysis ootaxa reveals a peculiar point contradiction with phylogenetic results based on skeletal remains: Megaloolithidae belonged to dinosaurs, which appear be sister group hadrosaur eggs (Spheroolithidae oofamilly). This result could indicate significant amount homoplasy evolution eggshell structures, depending strongly incubation environment (particularly for some characters ornamentation, pore openings and canals), reproductive physiology oviduct function. Bajocian eggshells might represent earliest offshoot oofamily record Laurasia supercontinent.