Spinosaurus News ~

[Ngala]

@Pckts

According to Ibrahim et al. (2014):

"Reduction of the pelvic girdle and hindlimb and the concomitant enhancement of axial-powered locomotion are common among semiaquatic vertebrates. The flexibility of the tail and the form of the neural spines in Spinosaurus suggest tail-assisted swimming. Like extinct and extant semiaquatic reptiles, Spinosaurus used lateral undulation of the tail, in contrast to the vertical axial undulation adopted repeatedly by semiaquatic mammals.
The dorsal “sail” in Spinosaurus, the tallest axial structure documented among dinosaurs, has been argued to be a thermoregulatory surface, a muscle- or fat-lined hump , or a display structure. Stromer drew an analogy to the skin-covered neural spines of the crested chameleon, Trioceros cristatus (Fig. 4E). As in T. cristatus, the sail of Spinosaurus is centered over the trunk. The shape and positioning of the spine are also similar, and the base of the neural spine is expanded anteroposteriorly, with edges marked by ligament scars. In Trioceros, a tendon of multisegmental axial musculature attaches to the expanded base of the neural spine (Fig. 4E). The upper portion of the spine has sharp anterior and posterior edges, is marked by fine vertical striae, and is spaced away from adjacent spines, unlike the broader, contiguous, paddle-shaped dorsal spines of other spinosaurids. The striated surface, sharp edges, and dense, poorly vascularized internal bone of the spines suggest that they were wrapped snugly in skin and functioned as a display structure that would have remained visible while swimming."

*This image is copyright of its original author

Fig.4 (E): Dorsal vertebrae with tall neural spines and spinal tendons in a cleared and stained specimen of Trioceros (Chamaeleo) cristatus (FMNH 19886).
Abbreviations: ns, neural spine; sc, scapula; te, tendon of multisegment spinal muscle.
Photo credits: Ibrahim et al. (2014) Reply