SEXUAL intercourse was far more common in early vertebrates than anyone imagined. So suggests a new study of ancient shark-like creatures called placoderms.
Last year, John Long of Museum Victoria in Melbourne, Australia, and colleagues found an embryo complete with umbilical cord inside a placoderm fossil from the Gogo formation in Kimberley, Western Australia. This “mother fish” pushed back evidence of internal fertilisation and live birth by 200 million years to 380 million years ago. But how placoderms managed to mate, considering some orders could grow to be 6 metres long and all…
