Scientists have discovered the world's oldest petrified sperm, dating to the early Miocene epoch, between about 23 million and 16 million years ago. The relatively giant sperm belonged to a tiny crustacean called a seed shrimp or ostracod. Here, a modern ostracod (Newnhamia). These tiny crustaceans create sperm longer than their own bodies. [Read the full story on the petrified sperm
Nanotomography of an ancient female Newnhamia (Newnhamia mckenziana), showing numerous giant sperm preserved inside the seminal receptacles.
A 3D reconstruction of Heterocypris collaris, a male ostracod dating back 16 million years.
Slice of Ostracod
A virtual slice of a female Newnhamia mckenziana from about 16 million years ago. The arrows point to spiral canals, which are large pathways for a male's giant sperm to travel to reach the female's sperm receptacles.
,A cross section of a male Heterocypris collaris, showing Zenker organs, which act as sperm pumps, as well as sperm stored in the seminal vesicle and ducts.
A cross-section of the seminal vesicle of the male Heterocypris collaris, with the nucleus of each sperm visible.
Modern Giant Sperm
A modern analogue: Sperm from today's Australian salt lake ostracod, Mytilocypris mytiloides.
A coiled bundle of giant sperm cells from the male’s seminal vesicle of the modern Australian salt lake ostracod, Mytilocypris mytiloides
The modern freshwater ostracod Eucypris virens also uses giant sperm cells for reproduction, although it is not a record holder with sperm being around 1.2 times as long as the male’s body.
A 16 million-year-old ostracod imaged with a light microscope, scanning electron microscope and with synchrotron microtomography. Blue lines highlight Zenker organs.
Soft Tissue Fossil
An external view of a 16 million-year-old ostracod with soft tissue preserved.