The species, which scientists named Diplomoceras maximum, lived approximately 68 million years ago in the waters near modern Antarctica.
D.maximum was a large, squid-like creature - its shell was more than 1.5 meters in height. It was an ammonite and part of a now extinct group of tentacled cephalopods. D. maximum became extinct at the same time as the dinosaurs, presumably for the same reason - due to the collision of the Earth with an asteroid, which formed the Chicxulub impact crater.
What particularly distinguished Diplomoceras wasthe unique shape of its shell. The top is curved both backwards and forwards, resembling a paperclip. In this new work, scientists have discovered something else remarkable about the ancient creature: its lifespan.
A sketched reconstruction of a typical Antarctic marine environment from the Cretaceous period, including the ammonite Diplomoceras in the form of a paper clip. Credit: James Mckay (jamesmckay.info).
A couple of researchers examined the shell of the specimen,which was previously discovered by other researchers. As part of their work, they investigated its chemical composition. Scientists have discovered repeating isotope signatures. The researchers speculate that the signatures were formed from methane that enters the water every year from the seabed. Methane left a trail annually covering the D. maximum shell. By adding up the number of methane ridges on the shell, the researchers were able to calculate its age. They found that D. maximum survived to about 200 years.
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