Oldest Mesosaur Embryos Hint at Early Live Birth in Reptiles
Researchers report 280-million-year-old mesosaur embryos from Brazil and Uruguay, providing the oldest direct evidence that these ancient aquatic reptiles could give birth to live young, pushing the origin of viviparity back about 60 million years; findings also indicate potential parental care, with some fossils suggesting a mixed strategy where at least one egg was found at an advanced stage of development.