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Images: World's Oldest Petrified Sperm

Modern Ostracod

Modern ostracod on black background

(Image credit: Renate Matzke-Karasz)

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

Ancient Sperm

ancient sperm in tiny crustacean

(Image credit: Renate Matzke-Karasz)

Nanotomography of an ancient female Newnhamia (Newnhamia mckenziana), showing numerous giant sperm preserved inside the seminal receptacles.

Male Ostracod

ostracod three dimensions

(Image credit: Renate Matzke-Karasz)

A 3D reconstruction of Heterocypris collaris, a male ostracod dating back 16 million years.

Slice of Ostracod

spiral canals in a female ostracod

(Image credit: Renate Matzke-Karasz)

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.

Sperm Cross-Section

sperm stored in ancient ostracod

(Image credit: Renate Matzke-Karasz)

,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.

Seminal vesicle

sperm in the ostracod vesicle

(Image credit: Renate Matzke-Karasz)

A cross-section of the seminal vesicle of the male Heterocypris collaris, with the nucleus of each sperm visible.

Modern Giant Sperm

modern giant sperm

(Image credit: Renate Matzke-Karasz)

A modern analogue: Sperm from today's Australian salt lake ostracod, Mytilocypris mytiloides.

Giant Sperm

modern giant sperm bundle

(Image credit: Renate Matzke-Karasz)

A coiled bundle of giant sperm cells from the male’s seminal vesicle of the modern Australian salt lake ostracod, Mytilocypris mytiloides

Modern Eucypris

eucypris ostracod

(Image credit: Renate Matzke-Karasz)

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.

Ancient Ostracod

ostracod imagery

(Image credit: Renate Matzke-Karasz)

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

soft tissue fossil of ostracod

(Image credit: Renate Matzke-Karasz)

An external view of a 16 million-year-old ostracod with soft tissue preserved.