Scientists have discovered fossils of ammonites – huge cephalopods that lived millions of years ago – on both sides of the ocean and studied them.

A new study has shown that about 80 million years ago, human-sized sea creatures were able to swim across the Atlantic Ocean. We are talking about Parapuzosia seppenradensis, a species of cephalopods extinct about 66 million years ago. They are known as the largest ammonites known to science and lived at the end of the Cretaceous period. The first specimen of molluscs was found in Germany in 1895. Its diameter is 1.8 m, despite the fact that the living chamber is only partially preserved.

In a new study, scientists have filled in the gaps in the evolutionary history of massive cephalopods. They studied 154 samples of fossil ammonites 80 million years old, collected in England and Mexico, 40 km north of Piedras Negras. And, if on the territory of Europe, fossils of mollusks have already been found, but the discovery of their remains on the other side of the Atlantic surprised scientists.

Paleontologists have suggested how the giant ammonites appeared on both sides of the Atlantic. It is generally believed that these ancient molluscs are quite slow swimmers, like modern nautilus. But perhaps the ammonites were able to cover great distances faster and swim more efficiently due to their impressive size. Another theory is that the extinct cephalopods may have crossed the ocean in the initial stages of growth, they were simply carried away by ocean currents.

Fossil analysis also showed that P. seppenradensis probably descended from a smaller related species, Parapuzosia leptophylla. It is known that its diameter was only 1 m.