A team led by University of Chicago Phenoscapers Nizar Ibrahim and Paul Sereno have published new findings about the remarkable semiaquatic predatory dinosaur Spinosaurus aegyptiacus in the latest issue of Science. It has been receiving some nice coverage at NPR and other news outlets.
From the abstract:
We describe adaptations for a semiaquatic lifestyle in the dinosaur Spinosaurus aegyptiacus. These adaptations include retraction of the fleshy nostrils to a position near the mid-region of the skull and an elongate neck and trunk that shift the center of body mass anterior to the knee joint. Unlike terrestrial theropods, the pelvic girdle is downsized, the hindlimbs are short, and all of the limb bones are solid without an open medullary cavity, for buoyancy control in water. The short, robust femur with hypertrophied flexor attachment and the low, flat-bottomed pedal claws are consistent with aquatic foot-propelled locomotion. Surface striations and bone microstructure suggest that the dorsal “sail” may have been enveloped in skin that functioned primarily for display on land and in water.
Citation: Ibrahim N, Sereno PC, Dal Sasso C, Maganuco S, Fabbri M, Martill DM, Zouhri S, Myhrvold N, Iurino DA (2014) Semiaquatic adaptations in a giant predatory dinosaur. Science. http://doi.org/10.1126/science.1258750.