The fossilized feces were left in the braincase of a fish millions of years ago by soft worms.

Researchers have found hundreds of tiny fossilized turds in a million-year-old fish skull. Not only is it a pretty remarkable discovery, it’s also the first time a skull filled with poop has been found.

coprolites

Under the right conditions, feces can fossilize. When that happens, they are also known as coprolites. The newly discovered coprolites were left behind by scavengers—probably worms—between 8 and 18 million years ago. After the stargazer fish died, worms living on the ocean floor ate their way through the skull. While the worms then feasted on the fish, they filled in the empty spaces with small feces.

Worms feeding on the brains of a dead fish left hundreds of tiny turds in the skull (seen here). Image: Calvert Marine Museum

The scientific name given to these micro-coprolites is Coprulus oblongus (which translates to ‘elongated fecal granules’). The turds are only a few millimeters in size and vary in color from gray to brown-black. Because such fossilized poops are frequently found in confined spaces or in areas thought to be inaccessible to invertebrates, they are attributed to small, soft worms that could squeeze themselves through tight spaces somewhat more easily.

Crocodile

By the way, if you’re eating, it’s best to put your sandwich down. Because in addition to this remarkable scene, the same research team also found some larger coprolites, about the same age. These have been pooped by a vertebrate, possibly an ancient crocodile. The researchers found that deep tunnels ran through these fossilized feces — which are about 18 centimeters long. The team suspects that these tunnels were excavated by poop-eating animals.

Fossilized crocodile poo with tunnels dug out by unknown poo-eating creatures. Image: Calvert Marine Museum

Which animals like to eat crocodile poop? The researchers still owe us the answer. They do, however, assume that the unknown animals feasted on the faeces by recycling the nutrients present in the faeces.

Takes place

Researchers found the two finds on impressive cliffs in the US state of Maryland, called Calvert Cliffs. Located in southern Maryland, the cliffs contain numerous fossils revealing life that once existed in the sea during the Miocene era. The coprolites are preserved in sediments that were deposited at the bottom of the Atlantic Ocean over millions of years as it covered southern Maryland.

While studying fossilized poop may not sound like a fun activity, it is well worth the effort. Just last year, for example, researchers found a previously unknown beetle in the 230-million-year-old faeces of a close relative of the Triassic dinosaurs. Studying millions of years old, fossilized turds is therefore a good alternative to amber fossils. The oldest insects that scientists have discovered in amber are about 140 million years old. In that respect, coprolites are a lot more interesting. Because thanks to thorough analyzes of such excrement, researchers can now look even further into the past.