Ancient Squid 'Beak' Fossils Found on Cretaceous Rocks Reveal They Dominated the Oceans In The Dinosaur Era

A collection of fossils has pushed back the evolutionary legacy of squids by more than 50 million years on Earth. These fossilized beaks emerged from the Cretaceous rocks in Japan, according to Cosmos Magazine. The remains were extensive, covering around 40 species from 23 genera and 5 families. The examination indicated that the squids dominated in dinosaur seas. This assertion was made based on the sheer number and size of these specimens. The discovery paints a new picture of the state of affairs in the waters of the dinosaur age. Findings regarding these fossils have been published in the journal Science. 

Past Knowledge About Squids

Cephalopods are a group that comprises squids, octopuses, and many other marine beings that supposedly emerged 500 million years ago. Since most beings in the group are soft-bodied, they don't fossilize well. It has caused issues for experts trying to trace the evolutionary trajectory of this group. Before the analysis of remains in Cretaceous rocks from Japan, the oldest known squid fossils were around 45 million years old, which caused researchers to speculate that squids evolved and succeeded in marine habitats after the extinction event that occurred 66 million years ago. This event spelled the end for dinosaurs and kick-started the dominance of squids. 

Challenging Past Assertions

The new study indicates that the squids dominated the marine habitats for much longer than researchers previously believed, according to Earth. The findings came by using a new method of analysis, in which the 100 million-year-old Cretaceous rocks were fully digitized in 3D rather than broken. In the digital images, the experts detected around 1,000 fossilized beaks belonging to ancient cephalopods. Amongst the 1,000 beaks, 263 belonged to squids, and around 40 seemed to be of an unknown species.

The features of squid beaks rejected the assertion that squids only rapidly evolved after the extinction event, 66 million years ago. The squid specimens detected in the rocks had diversified into many forms. It meant they evolved during the Age of Dinosaurs and not after its end. "These findings change everything we thought we knew about marine ecosystems in the past," said Associate Professor Yasuhiro Iba of the Department of Earth and Planetary Sciences at Hokkaido University. "Squids were probably the pioneers of fast and intelligent swimmers that dominate the modern ocean."

It implied that squids dominated marine habitats 100 million years ago. As far as their position in the marine ecosystem is concerned, researchers believe they were at the top of the food chain and acted as the main predators. This belief came from their numbers, diversification, and size.  They were surprised to find more fossils of squids in the rocks than beings like ammonites and bony fish. "In both number and size, these ancient squids clearly prevailed over the seas," said Dr. Shin Ikegami of the Department of Earth and Planetary Sciences at Hokkaido University, the study's first author. The size of squid specimens uncovered in the rocks was as large as bony fishes and more massive than the ammonites. It showcases that the squids were the most abundant swimmers in the marine habitats of the Age of Dinosaurs. 

Interconnection of Squids and Marine Ecosystem

Squids are one of the most active invertebrates living in the modern marine ecosystem. Their existence in both coastal and deep-sea environments gives them a crucial place in these modern habitats. In a way, squids have firsthand witnessed marine ecosystems transforming and developing over centuries. Being able to trace the history of squids, therefore, could give an idea about the development of marine ecosystems. Some squid specimens, like Myopsida and Oegopsida, detected in Cretaceous rocks, exist to this date. It means researchers have specimens to compare the present and past counterparts. These differences can also shed light on the state of ancient marine ecosystems, which, after the squid revelation, look very different to researchers.