A team of paleontologists has discovered what they believe is the world’s oldest animal sperm, frozen inside a tiny crustacean in a scrub of tree resin in Myanmar 100 million years ago.
The oldest known examples of fossilized animal sperm were previously only 17 million years old, according to the team of experts led by Wang He of the Chinese Academy of Sciences in Nanjing.
The sperm was found inside an ostracode, a crustacean species that has existed for 500 million years and can be found in many oceans today, the researchers said in an article published Wednesday in the prestigious Royal Society̵
They were found in the body of a female specimen, indicating that she must have been fertilized shortly before being trapped in the tree’s resin, experts said.
To make the find 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 equates to about 7.30 meters in a 1.70 meter human, so it takes a lot of energy to produce them,” Renate Matzke-Karasz of Ludwig Maximilian University Munich, co-author of the study, told AFP.
The ostracode was also a new species that scientists have called “Myanmarcypris hui”.
Quality more than quantity
Fossilized ostracod shells are common, but finding a specimen with “soft parts” is rare, experts said.
During the Cretaceous period (about 145-66 million years ago), the ostracods in question probably lived in the coastal waters of present-day Myanmar, where they were trapped in a clump of tree resin.
Most males in the animal world (including humans) generally produce tens of millions of tiny sperm, but for ostracods it’s about quality over quantity.
There are several conflicting theories about the evolutionary value of such giant spermatozoa.
“For example, experiments showed 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 life sperm. sperm, “Matzke-Karasz said.
This finding shows “that giant sperm reproduction is not an evolutionary extravaganza on the verge of extinction, but a serious long-term advantage for the survival of a species,” concluded Matzke-Karasz.