Australian scientists unveiled on Thursday the fossilized remains of the oldest vertebrate mother ever discovered, a 375-million-year-old placoderm fish with embryo and umbilical cord attached.
The fossil, found in the Gogo area of northwest Australia, is proof that an ancient species had advanced reproductive biology, comparable to that of modern sharks and rays, said John Long, head of sciences at Museum Victoria in Melbourne.
"It dawned on me after studying the specimen that this was the earliest evidence of vertebrates having sex by copulation," Long said.
The placoderms, often referred to as "the dinosaurs of the seas," were the rulers of the world's lakes and seas for almost 70 million years. Most species of the armored fish were quite small, but some were longer than 20 feet.