The way that spinosaurus hunt has been the subject of debate for many decades. Some believe they could swim, while others argue that it waded like a heron.

Now, paleontologists have taken a new approach in uncovering the decades-long mystery by examining fossils of close relatives of the dinosaur and other animals and comparing them to see how differences in bone density relate to their foraging behavior.

(Photo : Junko Kimura/Getty Images)
A Spinosaurus model is installed at Makuhari Messe on July 13, 2009 in Chiba, Japan.

The Largest Predatory Dinosaur's Hunting Habit

According to Science Daily, spinosaurus was the largest predatory dinosaur that ever lived. It was over two meters longer than the biggest Tyrannosaurus rex. Paleontologists analyzed the density of spinosaurid bones and compared them to other animals today, such as penguins, hippopotamus, and alligators, to find out how they hunt for food,

The team found that spinosaurus and its close relative Baryonyx from the Cretaceous period had dense bones that would have allowed them to submerge themselves underwater to look for food. Previous studies showed that spinosaurus had some kind of affinity with water given their elongated jaws and cone-shaped teeth that resemble fish-eating predators and the fish scales that were found inside the Baryonyx fossil.

Dr. Nizar Ibrahim, a paleontologist from the University of Portsmouth and an explorer for National Geographic, unearthed different parts of spinosaurus fossils in the Sahara Desert. He said that the bones had "water-loving dinosaur" written all over them. Dr. Ibrahim and his team believed that spinosaurus could swim and actively pursue prey underwater. However, other scientists disagreed.

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The Link Between Bone Density and Aquatic Foraging Behavior

Some scientists believed that spinosaurus waded in the water like a giant heron. Study lead author Dr. Matteo Fabbri from Chicago's Field Museum and an international team of researchers put together a dataset of the femur and rib bone cross-sections from 250 species of both extinct and living animals, either land or water dwellers, Phys.org reported.

They wanted a diverse group of animals in which they collected bones from big and small animals that weigh from just a few grams to dinosaurs with tons of pounds. These animals represent a clear link between bone density and aquatic foraging behavior since those that submerge to find food have bones that are almost completely solid throughout, whereas those with hollow centers are land-dwellers.

Fabbri said that the best explanation they could offer is the correlation between bone density and sub-aqueous foraging, which means that animals that can fully submerge themselves have dense bones.

The closely related species of Spinosaurus, the Suchomimus, has hollower bones that only allow it to wade on water and not swim. However, it still lived by the water and ate fish, as evident in its crocodile-like snout and conical teeth.

Moreover, MailOnline reported that not all animals with dense bones could submerge themselves underwater. For instance, giant-long neck sauropods, elephants, and rhinos all have dense bones, but that does not mean they were swimming. Fabbri explains that very heavy animals have very dense limbs because their heavy weight puts so much stress on the limbs.

The team published the full findings of their study, titled "Subaqueous Foraging Among Carnivorous Dinosaurs," in the journal Nature.

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