A team of paleontologists has discovered what they believe to be the oldest animal semen in the world, frozen inside a tiny crustacean in a drop of wood resin in Myanmar 100 million years ago.
According to a group of experts led by Wang He of the Chinese Academy of Sciences in Nanjing, the oldest known example of fossilized animal semen was only 17 million years old.
Sperm was found inside the ostracod, a species of crustacean that has existed for 500 million years and can be found in many oceans today.
They were found in the body of a female specimen, indicating that she was apparently fertilized shortly before she got into the resin of the tree, experts said.
To make the find even more special, semen was also described as a “giant”; whose size was 4.6 times the size of a male’s body.
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“This is equivalent to about 7.30 meters in a 1.70-meter person, so it takes a lot of energy to produce them,” said Renate Macke-Karash of the Ludwig Maximilian University in Munich, co-author of the study.
The ostracod was also a new species that scientists called “Myanmarcypris hui”.
Quality over quantity
Fossilized shells of ostracods are common, but finding a specimen with “soft parts” is rare, experts say.
During the Cretaceous period (about 145-66 million years ago), the ostracods in question lived, apparently, in the coastal waters of modern Myanmar, where they hit a point of wood resin.
Most males (including humans) tend to produce tens of millions of tiny sperm, but for ostracods it’s all about quality, not quantity.
There are several conflicting theories about the evolutionary value of such giant sperm.
“For example, experiments have shown that in one group, a high degree of competition between males can lead to a longer sperm life, while in another group, a low degree of competition also led to a longer sperm life,” said Matske-Karash.
This discovery shows “that reproduction by giant sperm is not an evolutionary extravagance on the verge of extinction, but a serious long-term advantage for the survival of the species,” concluded Matske-Karash.