Washington, May 29 : Australian scientists have reported the discovery of remarkably well-preserved fossil of a fish with an umbilical cord, dating back to about 375 to 380 million years ago.
John Long, head of sciences at Museum Victoria in Melbourne, has revealed that the fossil shows an embryo connected to its mother fish by an umbilical cord.
He describes it as the earliest evidence of a vertebrate giving birth to live young, shifting back the date some 200 million years.
He also calls the fossil the earliest record of vertebrate sex, since live birth occurs upon the fertilisation of an egg by male sex cells.
"Having such advanced reproduction for a fish that primitive is amazing," National Geographic quoted him as saying.
John revealed that the fossil represents a long-extinct placoderm, which are believed to be the most primitive jawed vertebrates that even predated sharks.
Often called the "dinosaurs of the sea", placoderms were the ruling class of marine creatures for 70 million years in the middle of the Paleozoic period, until their extinction about 360 million years ago.
John has revealed that the newfound mother fish is 10 inches long.
Kate Trinajstic, a paleontologist at the University of Western Australia, has revealed that much of the fish's soft tissue has been preserved in a three-dimensional state, making the fossil "basically an exact replica of the living animal."
"The material was so well preserved that we were able to pick up subtle details," Trinajstic says.
She says that it was on the back of such details that the researchers could determine the prehistoric mother and baby were a new species of ptyctodont, a type of placoderm having plates around the head and neck rather than the extensive body armour of its relatives.
The scientists have dubbed the species Materpiscis attenboroughi, a combination of "mother fish" and renowned naturalist Sir David Attenborough's name.
This is so because Attenborough's 1979 TV series 'Life on Earth' was the first to cast light on the scientific value the Gogo area in the Kimberley region of Western Australia, the site of an ancient barrier reef that once teemed with marine life.
A research article describing the newly found fossil has bee published in the journal Nature.