Wikipedia
Materpiscis
Materpiscis ( Latin for mother fish) is a genus of ptyctodontid placoderm (a class of extinct, superficially shark-like armored fishes) from the Late Devonian located at the Gogo Formation of Western Australia. Known from only one specimen, it is unique in having an unborn embryo present inside Materpiscis, and with remarkable preservation of a mineralised placental feeding structure ( umbilical cord). This makes Materpiscis the oldest known vertebrate to show viviparity, or giving birth to live young.