HE fossilized remains of two pregnant fish indicate that sex as we know
it - fertilization of eggs inside a female - took place as much as 30
million years earlier than previously thought, researchers said
yesterday.
Scientists from Australia and Britain studying 380
million-year-old fossils of the armored placoderm fish, or Incisoscutum
richiei, said they were initially confused when they realized that the
two fish were carrying embryos.
They originally thought the fish laid their eggs before fertilization.
"Once
we found embryos in this group, we knew they had internal
fertilization. But how the hell are they doing it," said John Long, the
head of sciences at the Museum Victoria in Melbourne, who wrote a paper
on the discovery that appeared in yesterday's issue of the journal
Nature.
"The clasper is an intermittent erectile organ that is inserted
inside the female to transfer sperm," said co-author Dr John Long, a
palaeontologist at Museum Victoria in Australia.
In one type of placoderm called the ptyctodonts, this organ is covered in bone and hooked.