Assertion: cetacean's jaw | /r/HasProperty | shallow or non-existent notch
Facets:
Source sentences:
text: They are characterized by having a lower jaw that extends at least to the tip of the upper jaw, a shallow or non-existent notch between the tail flukes, a dorsal fin set far backwards, three of four fused neck vertebrae, extensive skull asymmetry and two conspicuous throat grooves forming a 'V' pattern (which aid in sucking).