A recent discovery off the coast of Japan has turned what was known about the evolution of marine life in ancient times upside down. A team of paleontologists from Hokkaido University has managed to unearth fossil clues that had been hidden for millions of years, shedding light on the fundamental role that squid played in the oceans during the CretaceousThe research, published in the journal Science, uses innovative techniques and provides compelling data on the abundance and diversity of these animals, now considered the true rulers of the seas long before we imagined.
Until recently, it was believed that Squid only reached their peak after the disappearance of the dinosaurs. However, the results of this study demonstrate that these cephalopods were already marine protagonists long ago. about 100 million years, evolving and diversifying far ahead of what ancient records indicated.
Rocks with secrets: the discovery that changes everything
The starting point for this surprising discovery was a block of rock from the Upper Cretaceous, recovered from the Japanese coastal sediments. Thanks to a digital fossil mining technique —a procedure that involves sanding the rock layer by layer and scanning its interior in high resolution—, scientists discovered nearly 1.000 fossilized cephalopod beaks In perfect condition. These beaks, similar to small curved hooks, are the squid's most resistant part and offer the best window into their past.
Among all these fossils, the researchers recognized at least 263 copies of squid divided into about 40 species that were completely unknown until now. The size of some of these squids turned out to be so impressive that They even outnumbered fish and ammonites who lived with them, thus changing the idea of ​​who was the true king of the Mesozoic oceans.
The use of abrasion tomography has been key to this achievement. Thanks to it, every detail of the remains has been digitized and reconstructed in 3D without losing information, greatly improving the precision of paleontological studies. This method allows for the analysis of fragile microfossils, which are practically impossible to study with conventional cutting or dissection techniques.
Squids in marine evolutionary history
The conclusions of the study go far beyond the simple description of new species. quantity and size of the squid identified indicates that these animals had already achieved significant diversification and dominated food chains long before expected. According to the authors, These squid were not only abundant, but also the main marine predators in the ancient Japanese oceans, relegating the famous contemporary ammonites and bony fish to the background.
The research has also allowed the detection of the presence of two main groups of current squid: those from coastal waters (Myopsida) and those from the open sea (Oegopsida). This implies that the radiation and diversification of these animals began much earlier than previously accepted, thus rewriting the evolutionary history of cephalopods.
One explanation for why these squids have gone unnoticed for so long lies in their soft bodies, which rarely fossilize. However, their mouth beaks—hard structures—represent a valuable exception, allowing us to reconstruct their diversity and ecological role in ancient times. Until this discovery, only one ancient squid beak had been clearly identified., so the new discovery represents a significant advance in knowledge about these invertebrates.