You may think you have seen all of them if you have seen one. Most of the extinct cephalopods have coiled shells.
The species of ammonite is called Nipponites mirabilis. In place of the classic coiled-snake shell design, it replaced it with a convoluted shell that was not obvious from the beginning.
The piece of rope looks like someone threw it out the window.
The first time you look at it, it is a mess. You start to notice that there is a regularity there.
The forces acting on the shells of many mollusks were revealed by a mathematical model developed by Dr. Moulton and colleagues. The research was published in November.
The model suggests that the mollusk has a mismatch between its soft body and its hard shell, which causes asymmetric shell. The model explains how other snails develop their shells.
The mathematician who was not involved with the research said it was a beautiful result. The simplest model that can possibly produce all three forms is this one.
The paper is the latest collaboration between Dr. Moulton, Goriely, and Chirat. Three scientists are trying to understand the physics of seashell formation. They have published on the shells of sea snails and oysters.
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The N. mirabilis is from Japan.
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Chirat et al., PNAS 2021.
The team visited Dr. Chirat in Paris and spent an afternoon admiring the shells and ammonites within the Grand Gallery of Evolution.
Dr. Goriely said that like children inside Willie Wonka's factory.
The knots of the Japanese were not clear.
Dr. Chirat said over the phone from his office that he was obsessed with nichonites.
The shell of a mollusk is made using their mantle. The calcium carbonate is produced in the mantle. The researchers wanted to model the mollusk's soft body and shell as it hardened.
The ammonites left little traces of their squishy insides in the fossil record. The ammonites were symmetrical, like their living squid cousins, if you drew a line down the middle. The researchers assumed that ammonites were symmetrical.
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The National Museum of Nature and Science, Japan has a collection of Eubostrychoceras.
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Chirat et al., PNAS 2021.
How could a body have an asymmetric shell? There is a mismatch between the way the shell is growing and the way the body is growing. The whole premise of the model is that.
If the body grows faster than the shell, it will be too big for its shell house and will cause mechanical stress that will cause the body to twist inside. Imagine a long, hard tube stuffed with two soft pool noodles that are longer than the tube, as an analogy. The noodles twist inside the tube to relieve stress. The soft body twists as it rotates the edge of the mantle secreting the shell.
If the conditions are right, these abnormal shapes can emerge.
The weird shells of other unconventional ammonites were created by tweaking the level of mismatch and rigidity in the model.
Didymoceras is straight, a paper clip, and an upside-down ice cream cone coil.
The image is.
The N. mirabilis is from Japan.
The image is.
Chirat et al., PNAS 2021.
She said that there are other questions left unanswered by the model, including the biological costs, benefits and trade-offs of having such an asymmetric shell.
Recent research suggests that the wild shell of the Nipponites helped the ammonite in its search for prey. Kenneth De Baets, a paleologist at Friedrich-Alexander-Universitt Erlangen-Nrnberg in Germany, who was not involved with the new study, said he is curious to see how the model holds up as paleontologists uncover more soft ammonite tissue.
The animals have been dismissed as mistakes. It is a perfectly executed plan, a spiral coil of balance.
The new model shows that Didymoceras and Nipponites are more like ordinary ammonites than they appear.
She said that the idea that an animal could make a shell like this without moving heaven and Earth is credence. It wouldn't require a strange evolutionary leap.
