You might imagine that the spinosaur mind was one-of-a-kind. Trampling through the British Isles as many as 125 million years ago, it makes sense to think that these dinosaurs had something special swirling around inside their heads. But a paper published in the Journal of Anatomy says otherwise.
According to the paper, a team of researchers recently reconstructed the basic brain structure of two spinosaur specimens based off the shape and size of their braincases. And despite the fact that these fossil individuals would’ve lived strange, semi-aquatic lives when they were alive, their brains weren’t all that different from those of their terrestrial peers, whose lifestyles weren’t so specialized.
A Specially Built Brain?
Long ago, when the British Isles were almost completely covered with lagoons and lakes, lived a taxon of theropod dinosaurs with short arms, long legs and looming, sail-like structures along their spines. Lurking in the shallows in search of their food, these so-called spinosaurs feasted on fish and lived very differently than the terrestrial theropods, like the tyrannosaurs.
For a while, paleontologists thought that an assortment of anomalies in the spinosaur body and brain allowed these theropods to sustain themselves along the shores. In addition to their long, crocodile-like snouts and their sharp, tapered teeth, specialists speculated that the spinosaurs had a host of adaptations in their heads that helped them interact with their surroundings in their special, semi-aquatic way.
Setting out to study these adaptations, a team turned to two 125-million-year-old spinosaur skeletons, which are among the oldest in the world to still possess preserved parts of the spinosaur braincase. Finding that these fossils were almost whole, the team could reconstruct the internal tissue of their brains, revealing a surprising absence of adaptation.
“It seems the brains and senses of these early spinosaurs retained many aspects in common with other large-bodied theropods,” says Chris Barker, a study author and paleontology researcher at the University of Southampton, according to a press release. “There is no evidence that their semi-aquatic lifestyles are reflected in the way their brains are organized.”
To start their study, the team took CT scans of the fossil individuals, which represent two separate types of spinosaur from two separate regions of the British Isles, including a Baryonyx specimen from Surrey and a Ceratosuchops specimen from the Isle of Wight. Building off of these scans, the team then recreated the tissues of their brains, including the tissues which were involved in balancing the spinosaurs’ bodies and sorting through their sensory inputs, including sights, smells and sounds.
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“Using cutting-edged technology, we basically obtained all the brain-related information we possibly could from these fossils,” says Darren Naish, another study author and paleontology researcher at the University of Southampton, according to a press release. “It’s exciting to get so much information on sensory abilities.”
Though these abilities are typically seen as the trick to the spinosaurs’ semi-aquatic subsistence, the team’s recreations revealed that the spinosaurs’ brains were not any more attuned to their senses than those of the traditional, land-loving theropod.
“Because the skulls of all spinosaurs are so specialized for fish-catching, it’s surprising to see such ‘non-specialized’ brains,” Naish adds according to the same press release. “But the results are still significant.”
Ultimately, the team says that the terrestrial ancestors of these semi-aquatic therapods could’ve picked up the proper sensory adaptations for catching and consuming fish well in advance of the appearance of the first spinosaur. This suggests that their acquisition of a special snout and set of teeth was all they needed to survive on the shores.
“This new research is just the latest in what amounts to a revolution in paleontology due to advances in CT-based imaging of fossils,” says Lawrence Witmer, another study author and professor of paleontology at Ohio University, in the release. “We’re now in a position to be able to assess the cognitive and sensory capabilities of extinct animals and explore how the brain evolved in behaviorally extreme dinosaurs like spinosaurs.”