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.

Etymology
The species was named Materpiscis attenboroughi in honour of David Attenborough who first drew attention to the significance of the Gogo fish sites in his 1979 series Life on Earth.

Discovery
The holotype was found in the Kimberley area of northern Western Australia by Lindsay Hatcher during the 2005 expedition to the Gogo led by John Long of Museum Victoria. Fossils from the Gogo Formation are preserved in limestone nodules, so dilute acetic acid is used to dissolve the surrounding limestone and reveal the fossil.