Abstract
Recently a fossil of one of the earliest jawed fishes was found with a fetal skeleton and the remains of a cord. It was from the Devonian period and takes the history of vertebrate placentation back to 380 million years ago. This and later fossil evidence for viviparity in marine reptiles and early mammals is reviewed. Of particular interest are the fossils of horses as they document that a reproductive strategy with a single precocial newborn was evolved early on. In one instance there is sufficient representation of soft tissue to imply that early horses had a diffuse placenta, much as had been predicted by phylogenetic analyses of placentation.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
