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Newly-Found Fossil Hailed as World’s Earliest Recorded Male

By James Gorman

The New York Times -- A 425-million-year-old fossil found in Herefordshire, England, may be the oldest record of an animal that is unarguably male. Scientists report Friday in the journal Science that the tiny crustacean, only two-tenths of an inch long, had an unmistakable penis.

In their paper, the scientists name the creature Colymbosathon ecplecticos, which they say means swimmer with a large penis.

David J. Siveter, a geologist at the University of Leicester, said that although this was his literal translation of the Greek, it may, like so many other references to virility in males, be a bit of an exaggeration.

Colymbosathon, he said, was not remarkable among its group of crustaceans, the ostracodes. Some have copulatory organs one-third the length of their bodies, he said, and some produce sperm 10 times the length of their bodies. Colymbosathon is more modest; its penis was less than a fifth of its body length.

Siveter’s colleagues, who contributed to the research, were Derek E.G. Briggs of Yale and Mark D. Sutton and Derek J. Siveter, both of Oxford. The Siveters are twins.

There are many fossils, some earlier, that paleontologists judge to be male by overall size or other characteristics. But fossils may be a bit like the ultrasound images that prospective parents inspect so carefully -- only the presence of a penis is considered definitive.

Ostracode shells are common fossils and used in studies of ancient climate and of the pace of evolution. They are also used in oil exploration to help determine the age of drilled cores. And modern ostracodes are everywhere. They are common in oceans, shallow seas, rivers and lakes.

What is more remarkable than the sex of the fossil, Siveter said, is that it pushes back the presence of ostracodes 200 million years. Some fossils were presumed to be ostracodes, but with no soft body parts it was hard to know for sure, and such fossils are exceedingly rare.

The new fossil, of calcite found in volcanic ash, has modern descendants that are almost exactly the same, down to two hairs on the end of its swimming appendages.

It also offers a striking example of evolution almost standing still. “This,” Siveter said, “is an animal whose basic ground plan hasn’t changed in 425 million years.” It has evolved hardly at all.

A geologist at the U.S. Geological Survey in Reston, Va., Thomas M. Cronin, who uses ostracodes in a variety of research, said that it was “unbelievable to see the similarity with the living forms.”

Cronin also praised the detail with which the fossil was reconstructed. Siveter and colleagues ground the fossil down 20 microns (one one-thousandth of an inch) at a time, taking a digital photograph at each step. The photographs were combined in a computer to create a precise, three-dimensional, virtual reconstruction.