Life of the Oceans - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 157

gathering dust in a cupboard for years. The next curator of geology,
Roy Clements, stumbled across them one afternoon and suspected
there might be something more to these nodules than met the eye. He
passed them to his colleague David Siveter, a scientist who specializes
in the study of a group of small arthropods called ostracods. David
immediately looked at the nodules through a microscope. He then
looked up at Roy with some excitement. 'It's got legs,' he said.
There turned out to be legs, and heads, and bodies, and tails
a-plenty in those nodules, and hairs on the legs too. By painstakingly
cutting the nodules into thin slices, recording the pattern seen in each
slice, and then restoring the whole animal in three dimensions as a
virtual fossil, David Siveter and his colleagues—identical twin brother
Derek at Oxford, Derek Briggs at Yale, and Mark Sutton in London—
were able to begin the job of documenting the Herefordshire fauna.
They went back to the quarry where Bob King had made the first dis-
covery and traced the nodules to a layer of volcanic ash that fell on the
seabed some 425 million years ago. It was this ash that had entombed
the Herefordshire animals and frozen them in time, like an ancient
Pompeii of the Silurian seabed.
Within the Herefordshire deposit there are fossil relatives of mod-
ern horseshoe crabs, hairy worms, delicate crustaceans, striking
starfish, and sensational sea spiders, all preserved in three dimen-
sions. There are even brachiopods, with their fleshy holdfasts intact,
and also those small arthropods called ostracods beloved by David
Siveter. These animals have been known as fossils for two centuries,
although only from their hard skeleton—the carapace of calcium
carbonate that survives after the death of the animal. But in the
Herefordshire Lagerstätte these fossils also show exquisitely pre-
served swimming appendages and—to the delight of the media—
their impressive reproductive organs: ostracods may be small, but
males possess the largest penis and sperm relative to their size of any