As a team of paleontologists led by Dr. Benjamin Bomfleur of the Swedish Museum of Natural History was sifting through rock samples from Antarctica, they made a rather unexpected and unusual find – a fossilized animal sperm believed to be the oldest ever discovered.
The discovery, which was reported in Wednesday’s edition of the journal Biology Letters, was made by Dr. Bomfleur’s colleague Stephen McLoughlin and is believed to have originated from a family of creatures that includes earthworms and leeches, according to BBC News.
While fossilized plant sperm is common, the researchers said that only a few other specimens of fossilized animal sperm have ever been discovered, and the newly discovered Clitellata sample is believed to be 10 million years older than the previous record-holder for oldest animal sperm.
Dr. Bomfleur told the BBC that this was a “remarkable discovery” because “sperms are very transient, very short-lived, with soft cellular structures.”
So how did this accidental discovery happen?
While on an expedition at Seymour Island in the Antarctic, paleobiologist Thomas Mörs found a fossilized cocoon that he though may have contained plant remnants, the Washington Post noted. He passed the cocoon on to Dr. Bomfleur and his colleagues, who began analyzing it in search of those plant remains when they discovered the fossilized sperm remains.
The museum team sent pictures of the specimen along to Marco Ferraguti, an expert in annelid sperm. (We have experts on that?) The specimen underwent radiometric dating and was found to be at least 50 million years old, and after being compared to Ferraguti’s enormous collection of sperm pictures, the sperm likely belonged to a “crayfish worm.”
Experts report that the sperm probably survived as long as it did because of the biology of the creature from which it originated. These ancient worms secrete cocoons approximately 2mm in size that protect egg and sperm cells while they reproduce. The cocoon is formed from a sticky mucus that grows harder and is capable of trapping biological material in its walls.
Don’t expect a worm version of Jurassic Park, however
Even though the sperm is well preserved, Dr. Bomfleur said not to expect it to be used to create a worm version of Jurassic Park. “It might appear as if it was preserved in perfect detail but in the end the structure itself is fossilized,” the paleontologist explained to BBC News.
“We have the outer shape and form of the sperm cells preserved. We might even have internal, anatomical make-up of the sperm cells still preserved, we are not sure about that yet – we need to scan those using x-ray,” he added. “But even if anatomy should still be preserved, the material that it is composed of is altered so it’s not the original, organic material that the past animal sperm is composed of.”
(Image credit: Swedish Museum of Natural History)
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