nostrils being on the sides of its snout—far from the tip—and the form of the post-cranial skeleton), but thought it was capable of swimming, like most land vertebrates. They speculated that the elongated skull, long neck, and strong humerus of Baryonyx indicated that the animal was a facultative quadruped, unique among theropods. In their 1997 article they found no skeletal support for this, but maintained that the forelimbs would have been strong enough for a quadrupedal posture and it would probably have caught aquatic prey while crouching—or on all fours—near (or in) water. A 2014 re-description of Spinosaurus by the German-Moroccan palaeontologist Nizar Ibrahim and colleagues based on new remains suggested that it was a quadruped, based on its anterior centre of body mass. The authors found quadrupedality unlikely for Baryonyx, since the better-known legs of the closely related Suchomimus did not support this posture. Various theories have been proposed for the tall neural spines (or "sails") of spinosaurids, such as use in thermoregulation, fat-storage in a hump, or display, and in 2015, the German biophysicist Jan Gimsa and colleagues suggested that this feature could also have aided aquatic movement by improving manoeuvrability when submerged, and acted as fulcrum for powerful movements of the neck and tail (similar to those of sailfish or thresher sharks). In 2017, the British palaeontologist David E. Hone and Holtz hypothesized that the head crests of spinosaurids were probably used for sexual or threat display. The authors also pointed out that (like other theropods) there was no reason to believe that the forelimbs of Baryonyx were able to pronate (crossing the radius and ulna bones of the lower arm to turn the hand), and thereby make it able to rest or walk on its palms. Resting on or using the forelimbs for locomotion may have been possible (as indicated by tracks of a resting theropod), but if this was the norm, the forelimbs would probably have showed adaptations for this. Hone and Holtz furthermore suggested that the forelimbs of spinosaurids do not seem optimal for trapping prey, but instead appear similar to the forelimbs of digging animals. They suggested that the ability to dig would have been useful when excavating nests, digging for water, or to reach some kinds of prey. Hone and Holtz also believed that spinosaurids would have waded and dipped in water rather than submerging themselves, due to their sparsity of aquatic