Not all giant theropods had a strong bite, and skull evolution played a major part in that.
A new study in Current Biology analyzes the skulls of 18 large prehistoric predators, including the Tyrannosaurus rex, the spinosaurs, and allosaurs, and found that just because they were similar in size, it did not mean they all had strong bites.
“Carnivorous dinosaurs took very different paths as they evolved into giants in terms of feeding biomechanics and possible behaviors,” said Andrew Rowe of the University of Bristol, U.K., in a press release.
“Tyrannosaurs evolved skulls built for strength and crushing bites, while other lineages had comparatively weaker but more specialized 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.”
Evolution of Theropod Skulls
Massive theropods, such as T. rex and Spinosaurus, are popular among dinosaur enthusiasts, especially when depicted on the silver screen in films like Jurassic Park. Rowe and study co-author Emily Rayfield are also fans of these giant, bipedal dinosaurs. Through their study, they aimed to determine how being bipedal may have influenced the evolution of theropod skulls and their feeding techniques.
Though they might battle it out on the big screen, most of these giant theropods lived in different parts of the world and during different periods, and thus likely never interacted. And while they are similar in size, these predators also have vastly different skull shapes. Because of this, the study team wanted to know if the different skull shapes also meant different skull functions.
Read More: Massive, Dead Dinosaurs May Have Made Scavenging Irresistible
Scanning Theropod Skulls
For this study, the research team analyzed the body size and skull biomechanics of the dinosaurs. They used a CT scan (computed tomography) and other 3D technologies to measure bite strength, quantify the feeding performance, and analyze the skull mechanics.
According to the study, the research team assumed they would notice differences between all the skulls, but they were surprised to find a clear biomechanical divergence.
“Tyrannosaurids like T. rex had skulls that were optimized for high bite forces at the cost of higher skull stress,” Rowe said in the press release. “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.”
Larger Doesn’t Mean Stronger
The study results further revealed that skull stress didn’t necessarily increase with size. Some smaller theropods had a stronger bite force than larger theropods due to increased muscle volume. Bigger skulls didn’t mean stronger bites. For instance, though Spinosaurus and Allosaurus were larger theropods, the study results found that they wouldn’t have had a strong bite force; instead, they would have likely ripped and torn flesh.
“I tend to compare Allosaurus to a modern Komodo dragon in terms of feeding style,” Rowe said in a press release. “Large tyrannosaur skulls were instead optimized 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 specialization.”
Read More: Fossilized Teeth Offer Clues to Dinosaurs’ Favorite Foods About 150 Million Years Ago
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A graduate of UW-Whitewater, Monica Cull wrote for several organizations, including one that focused on bees and the natural world, before coming to Discover Magazine. Her current work also appears on her travel blog and Common State Magazine. Her love of science came from watching PBS shows as a kid with her mom and spending too much time binging Doctor Who.
