The Spinosaurus, one of the largest carnivorous dinosaurs ever unearthed, could hunt underwater, according to a new study published in Nature.
The study was a joint collaboration between the Field Museum of Natural History in Chicago, the University of Oxford, and the University of Cambridge which employed X-ray imaging of fossilised bones to assess bone density.
Spinosaurids were amphibious hunters, their diet consisted of meat and seafood, according to fossilised gut contents. Although it’s unclear whether they captured fish in the water like a crocodile or scouted from the shallows like a heron.
Spinosaurus weighed up to 7 tonnes and had a huge crest-like sail along its back, comparable to T. rex. Based on their long snouts and tail fins, researchers believe they may have been utilised for propulsion in water with some palaeontologists believing spinosaurids were specialised aquatic predators. The majority of dinosaurs walked on land, according to fossil footprints, therefore, proof of swimming is rare.
The researchers gathered femur and rib bone cross-sections from more than 200 living species, as well as those that hunt in the water like otters and others that scavenge on land like badgers, and used CT scanning – a type of 3D x-ray imaging.
These cross-sections were compared to those of a variety of dinosaurs, including three spinosaurids: Spinosaurus, Baryonyx, and Suchomimus.
The scans revealed that creatures that hunt for food underwater had bones that are virtually rock solid consistently, whereas land-dwellers’ bones exhibited cross-sections that resembled a doughnut with hollow centres.
Both the Spinosaurus and the Baryonyx had dense bones, indicating full submersion, although their close relative, Suchomimus, had hollower bones.
While it still thrived near water and ate fish which explains its crocodile-like snout and conical teeth, it wasn’t swimming to hunt, evident in its bone density.
