Preterm birth
James Elgin Gill (born on 20 May 1987 in Ottawa, Ontario, Canada) was the earliest premature baby in the world, until that record was broken in 2014. He was 128 days premature (21 weeks and 5 days' gestation) and weighed . He survived.
Chaohusaurus
One specimen among those reported in 2014, AGM I-1, also contained the remains of two embryos and one neonate. "Chaohusaurus" thus birthed its young viviparously in the water, like later ichthyosaurs. However, from the orientation of both the embryos inside the maternal body and the neonate that had already been giving birth to, it was clear that the young exited the birth canal head-first. This differs from the method used by most extant marine viviparous Amniota, which expel the young tail-first to prevent them from suffocating. Many younger ichthyosaur specimens had earlier been found showing embryos in both positions, leaving it undecided which was the normal one. Motani "et alii" (2014) concluded that, because "Chaohusaurus" is a very basal form, this provided strong evidence that, at least originally, ichthyopterygian young were born with the head first. This early method might have later been changed because it resulted in a too high mortality. They also cited this as evidence for a terrestrial evolution of viviparity in the land-dwelling ancestors of ichthyosaurs. AGM I-1 in 2014 represented the oldest reptile viviparous birth known.