T.rex’s massive skull was built for crushing but a new study has found the skulls of other giant carnivorous dinosaurs, such as Spinosaurus and Allosaurus, were instead designed for slashing and tearing…
T.rex and other meat-eating dinosaurs belong to a group known as Theropoda. This group includes three distinct lineages that independently reached gargantuan proportions: Megalosauroidea, Allosauroidea, and Tyrannosauroidea.
While these dinosaurs were all giant, bloodthirsty superpredators that used jaws lined with dozens of razor-sharp teeth to kill and dismember their prey, the exact murder methods they used were very different, say authors of a new study published earlier this month in Current Biology.
“Carnivorous dinosaurs took very different paths as they evolved into giants, in terms of feeding biomechanics and possible behaviours,” said the study’s lead author Andre Rowe of the University of Bristol, UK, in an associated press release.
“Tyrannosaurs evolved skulls built for strength and crushing bites, while other lineages had comparatively weaker but more specialised skulls, suggesting a diversity of feeding strategies even at massive sizes. In other words, there wasn’t one ‘best’ skull design for being a predatory giant; several designs functioned perfectly well.”
It has long been known that, despite being similar sizes, not all giant theropods had the same shaped skull. For example, a T.rex’s is relatively short but deep and full of dagger-shaped teeth, while a Spinosaurus’ is long, slender and full of needle-like teeth.
Nevertheless, both T.rex and Spinosaurus have giant skulls and, until recently, scientists generally thought that a giant skull translated to a powerful bite.
This new study has revealed this isn’t exactly the case, at least in two lineages of giant theropods: Megalosauroidea and Allosauroidea.
Using a combination of CT scans and 3D finite element analysis (a technique used for analysing stress in bones and other materials), Rowe and co-author Emily Rayfield found the skulls of megalosauroids (e.g. Spinosaurus) and allosauroids (e.g. Allosaurus) experienced less stress when biting than the skulls of tyrannosaurids.
This suggests they didn’t rely on brute force when it came to biting and instead adopted less-force-intensive strategies, such as slashing at their prey before ‘delicately’ stripping them of their flesh. T.rex and other tyrannosaurids weren’t so deft and instead used their powerful skulls to deliver bone-crushing bites.
“I tend to compare Allosaurus to a modern Komodo dragon in terms of feeding style,” said Rowe. “Large tyrannosaur skulls were instead optimised like modern crocodiles with high bite forces that crushed prey. This biomechanical diversity suggests that dinosaur ecosystems supported a wider range of giant carnivore ecologies than we often assume, with less competition and more specialisation.”
Rowe and Rayfield hypothesise tyrannosaurids evolved such powerful bites in order to subdue the increasingly large and mobile prey they lived alongside during the Late Cretaceous (100 to 66 million years ago). They also suspect tyrannosaurids may have been pushed into this strategy as a result of ecological displacement by coexisting predators, such as smaller meat-eating dinosaurs and giant crocodyliforms.
The fact that tyrannosaurids, megalosauroids, and allosauroids all rose to ecological dominance in their respective environments despite contrasting feeding strategies ultimately suggests there were many, equally successful ways to be a giant, meat-eating dinosaur.
Some, such as tyrannosaurids, pursued a high-risk, high-reward strategy that put their skulls under immense stress, while others, such as megalosauroids and allosauroids, practiced more delicate strategies that require a lot more finesse.
This study is published in the journal Current Biology and was conducted by the University of Bristol’s Andre Rowe and Emily Rayfield.