Follow the link below to a 3D model that was created by scanning the type specimen of Odobenocetops, which is housed in the Department of Paleobiology’s collections at NMNH, and cataloged as USNM 488252.
Link to Smithsonian paleontologist, Nicholas Pyenson's 3D scan of the skull of O. peruvianus:
http://www.3d.si.edu/tour/walrus-whale-odobenocetops
Link to Pyenson lab blogpost, detailing the scan of the Odobenocetops type specimen:
http://nmnh.typepad.com/pyenson_lab/2012/03/scanning-the-walrus-whale.html
Odobenocetops peruvianus was described by Christian de Muizon in 1993 and is early Pliocene in age (5.3 - 3.6 m.y.). It was discovered in southern Peru (de Muizon, 1993). The genus Odobenocetops is a bizarre one that is comprised of two species, O. peruvianus and O. leptodon (de Muizon, 1993). These two species are quite an extraordinary case of convergent evolution and a truly bizarre form of cetacean (whales, dolphins and porpoises). While its post-cranial morphology looks like those of a typical odontocete (toothed whale), its skull and feeding habits seem to converge towards those of the modern walrus (Odobenus rosmarus) (de Muizon et al., 2002). This is rather amazing, considering that the walrus is a member of the Order Carnivora and is largely unrelated to whales.
O. peruvianus defies the evolutionary odontocete pattern, by having a rostrum (snout) that is sharply angled downwards and a nasal opening that is drifting back towards the tip of the snout (de Muizon & Daryl, 2002). It also has an arched palette that aids in suction feeding and large, asymmetrical tusks (de Muizon et al., 2002). It lived in coastal, shallow-water habitats and, like the modern walrus, fed on hard-shelled, benthic invertebrates (de Muizon, 1993; de Muizon et al., 1999; de Muizon et al., 2002).
Odobenocetops peruvianus possesses a cranial morphology that is quite aberrant among odontocetes (toothed whales) (de Muizon & Daryl, 2002). The species is unusual, because all other toothed-whale skulls have a suite of characteristics that define the Suborder Odontoceti (de Muizon, 1993; Perrin et al., 2009). These features include a large cranial vault that is paired with an elongated rostrum (snout), that is broad and paddle-like or narrow and beak-like (Perrin et al., 2009).
The morphologies exhibited by O. peruvianus include the loss of the typical elongated rostrum of cetaceans and the anterior (forward) migration of the bony nares (nasal openings), binocular vision that is directed upwards, enlargement of the bony process that holds asymmetrical tusks and a large vaulted palate (roof of mouth). This is similar to that of the suction-feeding walrus (de Muizon et al., 2002).
The aberrantly truncated and angled rostrum indicates that there was no melon (a fatty echolocative apparatus) that is seen in all other odontocetes. Therefore, we can infer that Odobenocetops was not able to echolocate. The rearrangement of upward facing eyes and binocular vision could have evolved as a sensory compensation for the lack of echolocative abilities (de Muizon et al., 1999; de Muizon & Daryl, 2002; De Muizon et al., 2002).
Several cranial features indicate that Odobenocetops peruvianus belongs to the odontocete (toothed whales) Superfamily Delphinoidea. More specifically, several diagnostic features of the skull revealed that Odobenocetops is related to the Monodontidae. Odobenocetops is thought to fill an ecological role that is similar to the walrus (Odobenus rosmarus), as it fed upon shallow-water benthic invertebrates. Much like the walrus, it most likely used its upper lip and powerful tongue to exploit the benefits of the suction feeding method. Suction feeding enables the walrus and O. peruvianus to consume hard-shelled molluscs and other hard-to-exploit invertebrates by sucking the soft inner-parts from their hard, calcified shells (de Muizon et al., 1999; de Muizon & Daryl, 2002; De Muizon et al., 2002).
O. peruvianus had large, posterior (or backwards) facing tusks that could have played a role in their social lives, much like how they are used in the modern walrus. However, it has been argued that their main function was to orientate the animal when feeding because the tusks, and the sockets for these tusks within the skull, house large nerve bundles. The sensitivity and position of the tusks may have been an important indicator that they acted as orientation guides for the mouth, when feeding for mollusks along the shallow and muddy ocean floor (de Muizon et al., 1999; de Muizon et al., 1999; de Muizon & Daryl, 2002; De Muizon et al., 2002). This explanation for the importance of the tusk is generally well-accepted.
