Dinosaur-Era Fish Choked on Oversized Ammonite That Led To Its Fatal Death, Fossil Discovery Reveals

Scientists found a fossil of a fish from the dinosaur era that likely died after consuming an oversized ammonite shell, a type of extinct marine mollusk. It could have choked or suffered a stomach tear.

This marks the first instance of a fossilized fish found with a preserved large ammonite in its body. The fossil, originally excavated in 1977 in Germany, has been revisited to piece together the probable cause of the fish's demise.

Tuna-Like Fish Mistakenly Ate a Prey Too Big For It

The fossil, initially unearthed near Stuttgart, had been carefully stored away in a museum drawer. However, researchers have recently revisited this ancient discovery, delving into its details to reconstruct the circumstances of the prehistoric fish's demise.

Samuel Cooper, one of the researchers involved, emphasized that groundbreaking revelations in paleontology can sometimes emerge from unexpected places.

He highlighted in the study, titled "Death by ammonite: fatal ingestion of an ammonoid shell by an Early Jurassic bony fish" published in the journal Geological Magazine, that unexpected findings may be found by exploring museum collections and not just through traditional field expeditions.

The ancient fish is estimated to have lived approximately 180 million years ago, during the Jurassic period, when the region of southwest Germany was submerged in a warm and shallow sea teeming with enormous marine creatures, such as ichthyosaurs and plesiosaurs. This context provides insight into the environment that this particular fish inhabited during its time.

The tuna-like ancient fish called Pachycormus macropterus is one of the smaller marine organisms during the Jurassic era that spans only about 3 feet (0.9 metyyers) in length.

According to paleontologists, these Pachycormus fish typically opted for softer fare like squids as their diet, as noted by Cooper. Yet, at a certain juncture, one fish made an unconventional dietary choice.

Evidently, the fossil exhibits a distinct impression of a spiral ammonite shell, measuring around 4 inches (10 cm) in width, lodged against the fish's spine. Given the size of the fish, such a shell is most likely far too sizable to be ingested comfortably.

Cooper said it was like swallowing a plate-sized food. He proposes that the fish might have mistaken the shell for a more consumable piece of food, or it could have inadvertently swallowed the shell while eating around it.

First Documented Fatal Death a Pachychormid Fish

The researchers highlight that the ammonite was too big for the fish's digestive capabilities. They propose that the fish might have either misjudged the shell's nature or that it accidentally became lodged in its mouth for reasons unknown.

Once trapped, the fish likely couldn't expel the shell and was compelled to swallow it. As a result, the shell obstructed its passage to the intestine, inducing either blockage or internal bleeding, swiftly leading to the fish's demise within a matter of hours.

After its death, the fish seemingly sank to the ocean floor, where it was submerged in mud and eventually became interred. With the passage of time, it was preserved alongside its stomach contents, notably the well-preserved ammonite shell. This exceptional preservation provided tangible evidence for scientists to unearth millions of years later, shedding light on this prehistoric episode.

This remarkable discovery signifies the first documented instance of a fatal last meal found in an extinct pachycormid fish. Furthermore, the researchers posit that it implies ammonites might have constituted a more regular part of the diet of bony fish during the Jurassic era than previously assumed.

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