A clutch of crushed eggs and embryonic material from the Late Jurassic period, belonging to a large theropod dinosaur, have been discovered in the Lourinha Formation in Portugal. The find, reported in the journal Scientific Reports this week, represents the first eggshells and embryos ascribed to the group of dinosaurs known as megalosauroids, and could fill an important phylogenetic gap between two distantly related groups of theropods.
The discovery of fossilized dinosaur eggs and embryos together is rare, and non-avian dinosaurs with associated eggshells and embryos are represented only by the sauropod Massospondylus and a group of derived theropods called coelurosaurs. Ricardo Araujo and colleagues describe a large number of clustered eggshell fragments and embryonic bones and teeth, which they ascribe to the Torvosaurus, a large theropod that measured up to nine metres and weighed about two tonnes.
The authors conclude that these specimens represent the only unequivocal evidence of basal theropod embryos discovered to date, furthering our understanding of dinosaur eggshell structure and form, and bridging a phylogenetic gap among the theropods.