The largest predatory dinosaur of all time, the spinosaurus, was an aquatic animal capable of hunting underwater: the proof is in its bones, which are among the densest and most compact in the entire animal kingdom and probably served as ballast. to facilitate immersion.
This can be seen from the comparison with the bones of 250 fossil and living animal species, carried out by an international team of paleontologists including the Italians Matteo Fabbri of the Field Museum of Chicago, Cristiano Dal Sasso of the Museum of Natural History in Milan, Simone Maganuco and Marco Auditore collaborators of the same museum, and Gabriele Bindellini of the University of Milan.
The results are published today in "Nature".
The study took place in the laboratories and collections of naturalistic museums around the world, dissecting and observing under the microscope the bones of reptiles, mammals and birds, both fossil and current, as well as those of the well-known spinosaurus discovered in the Sahara (already in the center of several publications in Science and Nature) and those of two of its "cousins", the spinosaurids Baryonyx and Suchomimus. The results showed that the denser the bone tissue, the more adapted the animal is to live and feed in water. there are flying reptiles (pterosaurs) and birds, which have hollow and very light bones to fly, while at the other extreme there are spinosaurs along with many marine reptiles, cetaceans and hippos, which have almost full bones, with a medullary cavity very narrow or even absent.
That the spinosaurus was a skilled swimmer "we had already understood by observing the bones found in the Sahara, but now we have confirmation from the comparison with hundreds of extinct and living animals", underlines Dal Sasso. This new figure "integrates a set of characteristics that now leave little doubt about Spinosaurus' aquatic lifestyle, such as the small hind legs with webbed feet and the tail that was in effect a fin," adds Auditore.
The study of bone density reveals differences within the spinosaurid family, "suggesting that Spinosaurus and Baryonyx hunted their prey mainly in water - points out Matteo Fabbri, first author of the study - while Suchomimus was more on land", perhaps hunting his prey. without diving, a bit like herons do.
