Cover illustration. CTreconstruction of a Phocoena skull in anterior view; bone is rendered transparent and the pterygoid sinuses rendered in blue. High-resolution X-ray computed tomographic scans can be used to examine sinusoids within the vertebrate skull. In this issue of the Journal of Morphology Racicot and Berta employ CT imaging to study the pterygoid sinus morphology within extant porpoise species and one delphinid (pp. 49–62). The main goals of that study are: 1) detect intraspecific and interspecific variation among the studied species; 2) find the most parsimonious sequence of character acquisition; and 3) determine the potential functional roles of the preorbital lobes of the sinuses in sound reflection. The results of this study reinforce the importance of using nondestructive methods to quantify variation in endocranial anatomy and the value of CT data for recovering phylogenetically relevant information, as well as for analyzing the functional roles sinuses play in concert with the soft tissue head anatomy for biosonar.