It’s the sperm of perspective, is what it is. Nature is showing off the very seed of history – the oldest animal sperm ever discovered:
The remains of long, thin cells preserved inside the 50-million-year-old fossilized cocoon of an unknown worm species represent the oldest animal sperm ever found, say researchers at the Swedish Museum of Natural History in Stockholm.
Benjamin Bomfleur and his colleagues spotted the sperm fragments when they used an electron microscope to examine the inner surface of the cocoon fossil, which had been collected by an Argentinian expedition on Seymour Island, which lies off the Antarctic Peninsula. Their findings are published today in Biology Letters.
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Bomfleur says that the discovery was a surprise — “we laughed”, he says, on seeing the microscope images — “but in retrospect, it makes sense that you would find them as common inclusions in fossil cocoons”. The cocoons are secreted by some worms, including earthworms and leeches, which deposit sperm and eggs inside. Each cocoon then hardens to form a protective case for the developing embryos.
The researchers do not know what kind of worm left the sperm. Scanning electron microscope images show helical structures resembling drill-bits and beaded tails, which are characteristic of sperm produced by crayfish worms, leech-like creatures that live on freshwater lobsters. But these animals are found only in the Northern Hemisphere, so it would be surprising if they had existed in Antarctica 50 million years ago, Bomfleur says. “It could be an extinct relative with similar types of sperm.”
Apparently there’s no DNA inside the frozen, fossilized cell… so no cloned crayfish worms.