If anxious people have nightmares about being naked in public, an anxious ammonite may have dreamed of swimming around without his shell, exposing his soft body to the elements and predators.
For one unfortunate ammonite in the late Jurassic, it was not a dream, but a harsh reality. The animal died completely indistinctly outside its shell, and was thus buried. According to a study recently published in the Swiss Journal of Paleontology, the death of the ammonite made it an extraordinary fossil – one of the few reports of soft tissue in an animal that is usually immortalized as a shell.
“We know millions and millions of ammonites have been preserved from their shells, so something extraordinary had to happen here,” said Thomas Clements, a paleobiologist at the University of Birmingham in England who was not involved in the research. “It’s like finding -” said Dr. Clements, coming back. “Well, I do not even know what it’s like to find, it’s so weird.”
René Hoffmann, an ammonitologist at the Ruhr University Bochum in Germany, who reviewed the study, calls the fossil a ‘paleontological jackpot you only have once in your lifetime.’
To the untrained eye, the fossil looks more like an impressionist painting than an ammonite: a pink, bean-shaped smear surrounded by bumps, veins and ovals. It was discovered in the Solnhofen-Eichstätt region in southern Germany, which at the time of the ammonite about 150 million years ago was an archipelago with submerged, oxygen-depleted lagoons. According to Christian Klug, a paleontologist at the University of Zurich in Switzerland and the first author of the article, soft, dead creatures sank unscathed into the mud by predators or bacteria.
When Dr. Klug saw the fossil for the first time, he knew that it represented the soft parts of an ammonite, but exactly what soft parts he did not know. He left it alone for months until Helmut Tischlinger, a fossil collector and author on paper, sent him photographs of the fossil taken with ultraviolet light, revealing the minute increases and mineral stains in the fossil. has.
Dr. Klug successively reconstructed the anatomy of the being, from the most visible organs to the most obscure. First, he identifies the aptychus, a sudden lower jaw that indicates the fossil is an ammonite. Behind the jaws, he found the chitinous layer of the esophagus, and then a lump that represented a digestive tract with a cololite-fecal substance (he used another word) “that is still in the small intestine,” dr. Klug explained.
“Soft body reconstruction makes the most sense,” said Margaret Yacobucci, a paleobiologist at Bowling Green State University in Ohio who was not involved in the research.
Solving the other mystery of the fossil – how the ammonite was separated from the shell – was much more difficult. The soft parts were so intact that it looked like it was still rolled up. The authors suggest different alternatives in the ammonite’s life, each possible but uncertain. One suggests that the soft parts of a dead ammonite slipped out when the tissue connecting its body to its conch began to decay.
Another extensive explanation suggests that a predator breaks the shell of the ammonite from behind and sucks out its body to drop the naked ammonite. “The best explanation is that some squid-like organism pulls out the soft parts and could not pick them up,” said Dr. Klug said.
Dr. Clements finds the clumsy predator theory as ‘incredible’ if it is unlikely; presumably a combed ammonite body will do more visible damage. But he has no good alternative. The interpretation of a fossil always leads to some doubt, and Dr Clements predicts that the unarmed ammonite will be analyzed again in the future with robust chemical analyzes.
Oddly enough, the fossilized ammonite misses its arms, leaving one of the outstanding mysteries of ammonite anatomy unsolved. “Did they have very thin, fine arms, like modern nautiluses, or some strong arms, like modern koleoids?” Ask dr. Yacobucci. “If I had access to a time machine, the very first thing I would do was drive back to the Jurassic to see what kind of weapons had ammonoids.”
If an octopus-like predator did free the ammonite from its shell, it might have eaten the unknown amount of weapons of the creature as a consolation prize, feeding both ancient antlers and the scientists who studied them.
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