By Anna-Marie Lever
Science and nature reporter, BBC News
Engineering techniques have shown an unusual British dinosaur Baryonyx walkeri fed on fish, despite it looking like a meat-eater.
Baryonyx: Part-dinosaur, part-crocodile
The dino's skull bent and stretched in the same way as the skull of today's fish-eating crocodiles, even though it had clear differences in structure.
The early Cretaceous dinosaur was found in Surrey and lived at a time when the area was warmer and had lagoons.
The research is published in the Journal of Vertebrate Palaeontology.
"While Baryonyx and fish-eating crocodiles have similar elongate jaws, conical teeth and a 'nose' with a bulbous tip of teeth, there are differences in their structure," lead author Dr Emily Rayfield, from the University of Bristol, UK, told the BBC News website.
She explained: "Baryonyx has a narrow, domed skull, whilst crocodiles have a flat or tubular snout."
However, through a combination of techniques, Dr Rayfield and her colleagues have shown that, "both skulls functioned the same way".
CT scans show Baryonyx's teeth (yellow) had very deep roots
The team used CT scans to look at the internal anatomy of the skull, and a technique called finite element analysis.
This uses digital modelling to reconstruct how stress and strain affect a structure when loaded, and is more commonly used in engineering and design fields, for example to discover how a car bonnet buckles during a crash.
Co-author Dr Angela Milner, from London's Natural History Museum, adds: "Although Baryonyx and [fish-eating crocodiles] have independently evolved to feed in a similar manner, through the quirks of their evolutionary history their skulls are shaped in a slightly different way in order to achieve the same function.
"This shows us that in some cases there is more than one evolutionary solution to the same problem."