Journal of Mammalian Evolution

, Volume 12, Issue 1, pp 195-207

First online:

Anatomy of the Cranial Endocast of the Bottlenose Dolphin, Tursiops truncatus, Based on HRXCT

  • Matthew W. ColbertAffiliated withJackson School of Geosciences, The University of Texas at AustinGeological Science Department Email author 
  • , Rachel RacicotAffiliated withJackson School of Geosciences, The University of Texas at AustinBiology Department, San Diego State University
  • , Timothy RoweAffiliated withJackson School of Geosciences, The University of Texas at AustinTexas Memorial Museum, The University of Texas at Austin

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Endocranial surfaces, volumes, and interconnectivities of extant and fossil odontocetes potentially offer information on the general architecture of the brain and on the structure of the specialized cetacean circulatory system. Although conventional methods for acquiring such data have generally involved invasive preparation of the specimen, particularly in the case of fossils, new tomographic technologies afford nondestructive access to these internal morphologies. In this study we used high-resolution X-ray computed tomography (HRXCT) to scan a skull of the extant Tursiops truncatus (Cetacea: Odontoceti). We processed the data to reveal the cranial endocast and details of internal skeletal architecture (data at Major features that can be discerned include aspects of the specimen's hypertrophied retia mirabilia, the major canals and openings of the cranial cavity, and the relationship of the brain and endocranial circulatory structures to the surrounding skeleton. CT data also provide information on the shape of the brain that may be lost in conventional anatomical preparations, and readily provide volumetric and linear measurements of the endocast and its individual segments. These results demonstrate the utility of HRXCT for interpreting the internal cranial anatomy of both extant and fossil cetaceans.


Tursiops endocast computed tomography