Jurassic Fish Meet End Choking on Ancient Squid

Fossil Analysis Reveals Fatal Dining Habits

A long-extinct genus of ray-finned fish from the Jurassic period, known as Tharsis, apparently had a fatal flaw: an appetite for cephalopods bigger than they could handle, leading to frequent choking deaths.

Ancient Fish, Deadly Meal

A new analysis of fossilized Tharsis specimens reveals that these carnivorous marine animals often died with belemnites, an extinct group of squid-like cephalopods, stuck in their throats. According to paleontologists Martin Ebert and Martina Kölbl-Ebert from Ludwig Maximilian University of Munich, Germany, numerous Tharsis fish fossils discovered in the 152-million-year-old Solnhofen Plattenkalk formation show belemnites lodged fatally in their gullets.

Ebert and Kölbl-Ebert state in their paper that “A recent review of collection material … uncovered several specimens of Tharsis from the Late Jurassic Plattenkalk deposits of the Solnhofen Archipelago with belemnites wedged in mouth and gill apparatus.”

The researchers further explain that “In all cases, the rostrum [beak] reexits through the gill apparatus, whereas the broad phragmocone [internal shell] of the belemnite is firmly lodged in the mouth opening.”

Unlikely Diet, Fatal Mistake

Tharsis fish were micro-carnivores, typically feeding on small animals like larvae and zooplankton through suction feeding. Their fossils are relatively common. Belemnites, resembling squid with a long body and multiple arms, inhabited the open ocean, leaving behind fewer fossils. Interestingly, belemnite fossils from the Plattenkalk basins often feature internal shells overgrown with bivalves, suggesting they were dead and floating in the water column, colonized by other organisms. This is similar to modern whale falls, where whale carcasses on the ocean floor create ecosystems that can last for decades (Science, 2023).

Suffocation in the Jurassic Sea

Tharsis fish likely weren’t actively hunting belemnites on the seafloor. Instead, researchers propose that the floating, decaying cephalopods became a choking hazard. “Apparently, these micro-carnivore fish were in the habit of sucking remnants of decaying soft tissue or overgrowth such as algae or bacterial growth from floating objects, but when a streamlined floating belemnite rostrum accidentally was sucked into the mouth, they were no longer able to get rid of these deadly objects,” the paleontologists explain.

The paper concludes that “Even though the fish tried to pass the obstructive item through its gills, there was no way of getting rid of it, leading to death by suffocation.” In essence, their feeding habits proved to be a deadly evolutionary misstep.

The complete study is available in Scientific Reports.