Artist’s conception of a pregnant Dinocephalosaurus. What’s more, unlike the vast majority of the other 245-million-year-old and pregnant reptiles, one expectant mother of the species Dinocephalosaurus perished and became a fossil. Crucially, the embryo bones were aligned so that its body, though somewhat curved, would have pointed in the same direction as the adult’s. As aquatic reptiles cannot lay and incubate their eggs underwater, species like sea turtles must emerge on shore to lay eggs. There are various hypotheses as to why living archosauromorphs, such as birds, only lay eggs; these include the “biomechanical demands of flight,” as Liu and his colleagues noted.

Source: Washington Post February 15, 2017 09:12 UTC