In addition to their vision or echolocation, Christian de Muizon argues that they may have possessed tactile hair, which are also found in walrus and to a lesser extent in Amazon river dolphins.

[4] More substantial material was found in the form of three additional specimens, one of which is thought to represent a female O. peruvianus while the other two were described as a second, younger species named O. leptodon.

The other specimen of O. leptodon is a much less complete skull, badly weathered and missing the right tusk, but preserving an assortment of postcranial elements such as ribs, vertebrae and a partial forelimb.

The anterior most portion, which includes the premaxillae, tusks and nares is separated from the back of the head by a strong constriction, giving the skull somewhat of an hourglass-shape.

Among these adaptations is what is commonly referred to as "telescoping", a term that generally describes the fact that bones typically far apart are very closely spaced in cetaceans and largely overlap.

The tip of the snout, specifically the premaxilla, is covered in important insertion points for facial musculature while also housing a great number of neurovascular foramina.

[4] Like the rest of the skull, the periotic bone surrounding the inner ear is highly derived and does not closely resemble the typical anatomy expected from a cetacean.

[4] In addition to the unique shape of the skull, Odobenocetops is most easily distinguished from other cetacean by the presence of a pair of asymmetric tusks composed entirely of dentine.

These tusks are housed by large processes, known as the alveolar sheaths, formed by the premaxilla, which are directed back- and downwards at a 60° angle from the horizontal plane of the skull.

Due to the fact that the tusk additionally projects slightly towards the side, Odobenocetops could lower its head even further than that without having its tooth get in the way of its front flippers.

[3] Lipotidae "Pontoporiidae" Iniidae Hadrodelphis "Kentriodontidae"† Albireonidae† Odobenocetops Denebola† Delphinapterus leucas (Beluga whale) Monodon monoceros (Narwhal) Phocoenidae (Porpoises) Delphinidae (Dolphines) The melon, an important fatty sensory organ present towards the front of the head and associated with echolocation in toothed whales, appears to be either heavily reduced or entirely absent in Odobenocetops due to the highly specialised skull shape of the animal.

However, Muizon suggests that this may not have been a hindrance to the animal and that if positioned oblique to the seafloor, the enlarged and dorsally located eyes of the whale may have provided good binocular vision.

In the case of the enlarged right tusk, this facet runs parallel to the crest of the palate and the seafloor, indicating that the wear of the tooth may have been caused by it being dragged along the bottom of the ocean during foraging.

Muizon and colleagues argue that although the tusks were positioned in a way that would allow them to slash at the flanks of other individuals after approaching head on, their fragile nature seems to preclude the use in actual combat.

Furthermore, hydrofoils might not have been very useful for the slow-swimming Odobenocetops, the sheaths would have generated little lift and if anything been counterproductive when the animal tried to feed and their stiff attachment to the skull makes them less effective than flippers.

The sheaths are not dense enough to serve as ballast and are not angled correctly to form an effective plough during foraging (which would further clash with the interpretation that they might have been covered in tactile hair).

They may not have been points for muscle attachment, as the back of the skull already serves this purpose, and they appear to have been overdeveloped for simply restricting the area affected by their suction force.

Although Muizon and colleagues find flaws with these last two hypothetical functions, they cannot rule them out entirely and suggest that they may even have been factors in the early evolution, before the length of the sheaths reached the size seen in the known fossils of Odobenocetops.

The idea that they are a retained primitive feature on the other hand is questioned as it does not explain what caused them to attain their size in the first place, as they likely didn't serve to support the tusks.

Skin attached to the sheaths could have been an adaptation for feeding, protected the eyes from mud and sediment, while the use as orientation guides is an idea Muizon had already suggested in previous publications.

Muizon and colleagues suggest that it may have angled its head down while swimming, which would effectively bring the tusk into a position roughly parallel with the rest of the body and reduce drag.

Whichever the case, Odobenocetops shows pronounced points for muscle attachment on the basioccipital bone, which corroborates the presence of strong neck musculature that would be needed to compensate for the weight of the large tusks.

Muizon and colleagues contrast this to the position taken on by sirenians like the dugong, which are capable of swimming parallel to the seafloor thanks to their denser bonestructure relative to ceteaceans and pinnipeds.

[8] The great range of motion estimated from the articulation of the bones is further supported by the numerous strongly developed muscle attachments seen on the skull of Odobenocetops.

The deep palate, rounded snout supporting a strong upper lip, tusks and reduced dentition are all traits shared between this cetacean and walruses, both extant and extinct.

The glenoid fossa allows for forward and backward movement of the mandible while the temporalis muscle, masseter, tongue and throat musculature may have all contributed to moving the lower jaw back.

[3] All this combined indicates that Odobenocetops was a bottomfeeding molluscivore, detecting various bivalves or crustaceans either through, depending on the species, the use of echolocation or exceptional vision and possibly with the assistance of tactile hair.

Once a suitable prey item was detected, Odobenocetops could have created a powerful jet of water using its mouth (an ability also seen in belugas and orcas), excavating the target from the sediment.

It would then have likely used its powerful upper lip to grasp and hold the invertebrate in place before utilizing a complex suctionfeeding mechanism created by the palate and tongue to suck out the soft parts.

Contemporaneous vertebrates from this locality include the seal Acrophoca, balaenopterid and sperm whales, billfish, the shark Carcharodon, and the marine sloth Thalassocnus.