In the ocean deep when dinosaurs were young, a squid attacked a fish and promptly died with its tentacles still wrapped around its would-be dinner. Now, paleontologists excavating the mud-rock bed left from Jurassic Dorset have found the unique fossil of this submarine struggle almost 200 million years after the event.
Actually, the fossil had been found in southern England in the 19th century, but has been kept in the collections of the British Geological Survey in Nottingham, explain the authors of a new paper published Wednesday in the Proceedings of the Geologists’ Association. Now a new analysis has gone as far as to actually putatively identify the host and prey.
The squid appears to be a Clarkeiteuthis montefiorei, and the supper a herring-like fish called Dorsetichthys bechei, embraced in the squid’s tentacles and clamped in its jaws.
The struggle, locking them for eternity in each other’s company, seems to have happened in the Sinemurian period (a stage in the early Jurassic), between 190 and 199 million years ago, say the researchers from England’s University of Plymouth, the University of Kansas and Dorset-based company The Forge Fossils.
The unfortunate Dorsetichthys was a small bony fish that lived in the early Jurassic waters and has long gone extinct.
Usually fossils of marine creatures of yore are created by sediment falling on and protecting a dead life-form before microbes can completely destroy it; or it dies and sinks into mud (thus being protected from the microbes) that then hardens; or it wasn’t dead but sank into the mud or sediment anyway, and so on. These two were found in mudstone. The “teeth” seen in the fossil are hooks that had once been part of the squid’s arms and were used to latch onto prey.
In the case of fossil squids, what we usually see are lines of hooks that were buried in the tentacles (arms), which are what are preserved, Prof. Malcolm Hart, professor emeritus in Plymouth and the study’s lead author, explains told Haaretz: “Occasionally we see ‘carbon films’ that show the shape of the arms,” he adds.
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“Modern squid, and many fossils, have these small hooks in their arms that are made of chitin. They were presumably used for grasping prey,” he elaborates. “They are in paired lines in many of these older specimens. In some cases, there is one type – but we know some species that have more than one type of hook present.”
But couldn’t the fossil contain a proto-herring that fell onto a dead squid, or vice versa? Why think that evil fate interrupted a predation event? Because of the position of the tentacles vis-à-vis the herring: It suggests this was “not a fortuitous quirk of fossilization, but that it is recording an actual paleobiological event,” according to the University of Plymouth.
It seems that the squid managed to crush the fish’s head, before it too died – which could shed light on the reason for their simultaneous demise: Maybe it bit off more than it could chew and choked, or the fish got stuck in its maw, the paleontologists imply. Another possibility is that after catching the fish, the squid fled for the depths in order to avoid an even bigger predator and suffocated in the oxygen-poor water.
How can we tell the herring head was crushed by a bite, not the pressure of fossilization? “Because the bones in the head are broken across with very sharp edges more akin to a bite than gentle compression. We have modeled compaction elsewhere and know what it produces,” Hart says.
“Since the 19th century,” he adds, “the Blue Lias and Charmouth Mudstone formations of the Dorset coast have provided large numbers of important body fossils that inform our knowledge of coleoid palaeontology. In many of these mudstones, specimens of paleobiological significance have been found, especially those with the arms and hooks with which the living animals caught their prey.
"This, however, is a most unusual if not extraordinary fossil as predation events are only very occasionally found in the geological record. It points to a particularly violent attack which ultimately appears to have caused the death, and subsequent preservation, of both animals,” Hart says.
To be fair, all prey might think the attack by a predator is violent. But few such savageries lead to the death of the predator, who got caught in its brutality for all time in the fossil record.
Dinosaurs began to evolve around 230 million years ago; the earliest mammals, small rat-like creatures, began to develop shortly afterward. Fish predated them by almost 300 million years, with the earliest fish lineage dating to about 520 million years ago. Metaspriggina didn’t look like what we think of as fish, but it was.
And that is about the time that the earliest cephalopod mollusks – which would become octopi, cuttlefish and squids – began to evolve too. The earliest cephalopods half a billion years ago seem to have been shelled.
Said squid and meal date as said to about 200 million years ago.
While fish are not known for their advanced cognitive powers, with all due respect to the “Jaws” and “Sharknado” film franchises, octopi are considered to be among the most neurologically advanced of all invertebrates. They are not only tasty but clever, though that hasn’t made them gregarious – cephalopods can’t stand one another and some may well indulge in cannibalism.
On the upside, though, there are whole video libraries on YouTube devoted to octopi escaping from their aquaria to commit mischief, after which they may even slither back into their own enclosures and play innocent. But we know better.