Not all giant meat-eating dinosaurs were the terrifying, bone-crushing predators we imagine.
A new study published in the journal Current Biology has found that while many theropods – the group of bipedal carnivorous dinosaurs that includes Tyrannosaurus rex, Spinosaurus and Allosaurus – evolved massive bodies, only some developed the skull strength needed for high-powered bites.
Using 3D scans and computer modelling, researchers analysed the skull biomechanics of 18 theropod species.
They discovered that while T. rex had a skull optimised for delivering enormous bite forces – capable of breaking through bone – other giants had comparatively weaker jaws and relied on different hunting strategies.
“Tyrannosaurids like T. rex had skulls that were optimised for high bite forces at the cost of higher skull stress,” said lead author Dr Andrew Rowe of the University of Bristol, UK. But in some other giants, like Giganotosaurus, we calculated stress patterns suggesting a relatively lighter bite. It drove home how evolution can produce multiple 'solutions' to life as a large, carnivorous biped.”
Rather than following a single evolutionary route to apex status, giant carnivores evolved a variety of skull shapes and feeding styles. Some, like T. rex, bit down like a crocodile. Others, such as Allosaurus or Spinosaurus, used slashing or ripping techniques more comparable to modern Komodo dragons or big cats.
“Tyrannosaurs did something different,” Steve Brusatte, a professor and palaeontologist at the University of Edinburgh who was not involved in the study, told BBC Science Focus. “They supersized their heads and developed enormous bite forces, enough to break the bones of their prey. This was a risky and high-stress lifestyle, quite literally, as it put huge stress on its skull bones and muscles.”
The findings also challenge the assumption that bigger dinosaurs had stronger bites. Some smaller species actually placed more stress on their skulls due to increased muscle volume. This suggests that size alone wasn’t the main factor in bite power.
The diversity in bite strength and skull design suggests that dinosaur ecosystems were more specialised than previously assumed, with multiple ways to dominate the prehistoric food chain.
“There wasn’t one ‘best’ skull design for being a predatory giant; several designs functioned perfectly well,” Rowe said. “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.”
Read more:
- 7 dinosaurs we’ve all been getting completely wrong
- The T.rex was a massive coward – and we have the footage to prove it
- What if the dinosaurs had survived?
About our expert
Steve Brusatte is a professor and palaeontologist at the University of Edinburgh and the author of the book The Rise And Reign Of The Mammals (£20, Picador), a 325-million-year odyssey of mammalian evolution and the people who study mammal fossils.