This giant sail-backed dinosaur's hunting style is creating a furore among palaeontologists

The giant sail-backed dinosaur, Spinosaurus, might've hunted in the shallow waters like a heron, not in deep waters, as previous studies suggested.

Spinosaurus aegyptiacuswas one of the largest predators ever to walk on Earth during the Cretaceous, the final period in the time of dinosaurs.

According to the study published inPLOS ONE,this species from what is now Africa was about seven tonnes,more than a bull African elephant. Nathan Myhrvold, one of the study's authors, told Newsweek, "It's a very unique looking dinosaur because it has a huge 'sail' on its back."

Palaeontologists generally agree that the Spinosaurus was a fish eater. However, there has been a debate about how the dinosaur species lived and hunted its prey.

Some studies suggest that these dinosaurs waded or swam in the shallow waters near the shore to catch their prey. However, according to some studies, the Spinosaurus was an aquatic pursuit predator that searched for its prey by diving deep into the waters.

The authors of the new study conducted a new analysis where they re-analysed the density of the dinosaur's bones to determine its life habits in water. They discussed an earlier study that supported the hypothesis that the Spinosaurus dived into deep water to catch its prey.

The discussed study, authored by a different team led by Matteo Fabbri of the Field Museum of Natural History, was published in the journalNaturein 2020. In the new study, the authors said that the 2020 study might have significant flaws.

"We showed that the data set they used for the method was not appropriate—a lot of statistical methods only work if the data has particular characteristics. The data in Fabbri et al did not have the necessary characteristics," Myhrvold said.

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Myhrvold and his team added that this hypothesis cannot be feasible at the biological level. They mentioned that the Spinosaurus and many other dinosaurs had air sacs in the bones of their spine, which provided so much buoyancy that they could not dive.

"So the density of thigh and rib bones doesn't tell you whether a dinosaur could dive," Myhrvold said.

While the new study does not settle the debate, Myhrold said their objective was to prove that the Spinosaurus did not hunt underwater. Their findings suggest that the dinosaur was not a swimming or diving predator that chased fish.

"We find no evidence from bone density to suggest that Spinosaurus was anything other than what we have judged from many other lines of evidence in previous research—a semiaquatic, fish-eating predator that haunted shorelines and shallow water ambushing prey of all sizes," Paul Sereno, another author of the PLOS ONE study with the University of Chicago, said.

"It may have waited in shallow water to ambush fish the way a heron does," Myhrvold said.

In response, Fabbri said, "We don't think their data support their conclusions." He added, "Myrvhold et al. suggest that high bone density is present only in the legs, but this is incorrect: we recovered high density in the spines of the sail and tail, in the ribs, and even in the bones forming the hand."

(With inputs from agencies)