Researchers digitally reconstructed the two oldest spinosaurus brains

Lived in what now is North Africa during the Cenomanian to upper Turonian stages of the Late Cretaceous period, about 99 to 93.5 million years ago, spinosaurus is an unusual group of theropod dinosaurs, equipped with long, crocodile-like jaws and conical teeth. 

The University of Southampton and Ohio University researchers have reconstructed two British spinosaurus' brains and inner ears to understand how they interacted with their surroundings. 

Researchers scanned fossils of Baryonyx from Surrey and Ceratosuchops from the Isle of Wight. According to the University of Southampton, these two are the oldest spinosaurus for which braincase material is known. Across 125 million years ago, the enormous beasts would have been strolling around the Earth. Both specimens' braincases are in good shape, and the scientists used digital reconstruction to recreate the inside soft tissues that had long since decayed away.

The olfactory bulbs, which process scents, weren't well developed, and the ear was likely tuned to low-frequency sounds, according to the experts. The brain regions responsible for maintaining balance and a fixed gaze on prey may have been less developed than in later, more specialized spinosaurus.

“Despite their unusual ecology, it seems the brains and senses of this early spinosaurus retained many aspects in common with other large-bodied theropods – there is no evidence that their semi-aquatic lifestyles are reflected in the way their brains are organized,” said the University of Southampton Ph.D. student Chris Barker, who led the study.

It only needed to evolve

One interpretation of this data is that theropod ancestors of spinosaurus already had brains and sensory adaptations suitable for occasional fish catching and that spinosaurus only needed to evolve an atypical snout and teeth to become specialized for a semi-aquatic existence.

“Because the skulls of all spinosaurus are so specialized for fish-catching, it’s surprising to see such ‘non-specialized’ brains,” said contributing author Dr. Darren Naish. “But the results are still significant. It’s exciting to get so much information on sensory abilities – on hearing, sense of smell, balance, and so on – from British dinosaurs. Using cutting-edge technology, we basically obtained all the brain-related information we possibly could from these fossils,” Dr. Naish said.

The study was published in the Journal of Anatomy.