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Dr. “It’s preserved exactly the same size, the same age, the same place, the same proportions, and just slightly differently,” Klug said.
Not involved in the research, Dr. Clements said the new paper relies heavily on visual analysis methods and that these questions can be resolved with chemical analysis. “With a full technique, we would definitely have more clues or a lot more answers,” he said, noting that these techniques can be expensive.
Dr. When Whalen first studied the fossil, he looked for the phragmocone, a chambered shell that helps most fossil cephalopods control their buoyancy. A of nautilus phragmocone is its spiral shell; a squid is his cutting bone. Dr. The fossilized chambers of a phragmocone were divided by very distinctive and often well-preserved mineralized layers, Whalen said.
Dr. Whalen said that the G. beargulchensis fossil found in the American Museum of Natural History preserves these different layers. The authors argue that since this fossil and S. bideni were preserved in the same place and environment, the lines of both must have been preserved. However, S. bideni had no trace of these stripes, suggesting that the creature never had an internal chambered shell.
Dr. Whalen also expected to see evidence of a primitive rostrum, a mineralized counterweight to enable early cephalopods to swim horizontally. However, Dr. The S. bideni fossil did not have the rostrum, suggesting it was “never there,” Whalen said.
Instead, the researchers’ analysis found that the inner shell of S. bideni was a gladius, a triangular shell-like relic found in squids and vampire squids. Dr. “This is really not something anyone would expect to see in an animal this old,” Whalen said. “We knew we were looking for an early vampiropod.”
Dr. Klug disputed this conclusion, arguing that the shell was instead a deformed phragmocone and body chamber of the known cephalopod G. beargulchensis.
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