A team of paleontologists have discovered what they believe to be the world’s oldest animal sperm, frozen in a small crustacean in a drop of tree resin in Myanmar 100 million years ago.
The earliest known examples of fossilized animal sperm were only 17 million years old before, according to the team of experts led by Wang He from the Chinese Academy of Sciences in Nanjing.
The sperm were found in an ostracode, a type of crustacean that has been around for 500 million years and is found in many oceans today, researchers said in an article published Wednesday in the prestigious journal Proceedings of the Royal Society.
They were found in the body of a female specimen, indicating that she must have been fertilized shortly before being trapped in the resin of the tree, experts said.
To make the discovery even more special, the sperm have also been described as “giants,” measuring up to 4.6 times the size of the male’s body.
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“This is equivalent to about 7.30 meters in a human of 1.70 meters, so it takes a lot of energy to produce them,” Renate Matzke-Karasz of the Ludwig Maximilian University in Munich told AFP, co -author of the study.
Ostracod was also a new species that scientists named “Myanmarcypris hui”.
Quality rather than quantity
Fossilized ostracod shells are common, but finding a specimen with “soft parts” is rare, experts said.
During the Cretaceous Period (around 145 to 66 million years ago), the ostracods in question probably lived in the coastal waters of present-day Myanmar, where they got trapped in a drop of tree resin.
Most males in the animal world (including humans) typically produce tens of millions of tiny sperm, but for ostracods, it’s all about quality rather than quantity.
There are several conflicting theories about the evolutionary value of these giant sperms.
“For example, experiments have shown that in one group a high degree of competition between males can lead to a longer sperm lifespan, while in another group a low degree of competition also leads to a higher long sperm lifespan, ”said Matzke-Karasz.
This finding shows “that reproduction with giant sperm is not an evolutionary extravaganza on the verge of extinction, but a serious long-term benefit for the survival of a species,” concluded Matzke-Karasz.