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Oldest Known Male Fossil: 425 MYA

picture at



A fossil of a small sea creature extracted from a 425-million-year-old
British rock formation is the oldest unequivocally male fossil known,
researchers say.

The animal, a new member of a large species group called ostracode, was
buried under volcanic ash which mineralized and retained an image of its
soft body parts. That unique preservation enabled researchers to construct
a highly detailed three-dimensional picture of the animal after digging
the fossil from a rock bed in Herefordshire.

Details revealed include gills, eyes, limbs designed for swimming and the
oldest known male organ in the fossil record. It was this last that led
researchers to name the new species, Colymbosathon ecplecticos, which is
Greek for "amazing swimmer with large penis." 
Siveter and his team used a new technique that combined thin-film cutting
and data storage in a computer.

They removed the rock containing the fossil and then cut extremely thin
shavings through the remains. Each shaving was then photographed and
stored in a computer. Later, the researchers were able to electronically
reassemble the slices and create a three-dimensional image of the animal,
along with its soft parts.

That, Cronin said, has never been done before for such an ancient animal.

Modern relatives of C. ecplecticos are found in virtually every aquatic
environment on Earth, from deep oceans to shallow streams. They are
bivalves, but are more closely related to crabs and lobsters than to clams
or oysters. Most animals in this group graze on dead organic matter.

C. ecplecticos was about 0.20 inch at its widest dimension and its soft
body parts closely resemble those of its modern relatives. 

Cronin said this close similarity shows that the ostracode group of
animals has changed remarkably little over hundreds of millions of years,
even though most other species underwent significant evolutionary redesign
or disappeared altogether.

"This specimen shows what nobody has been able to show before - 425
million years of unbelievable stability in an organism," he said. "Most
things that lived in the Silurian are long extinct and don't have many
living relatives."