Description of an Anomalous Monodontid Skull From West Greenland: A Possible Hybrid?

The complete skull of an anomalous odontocete cetacean from outer Disko Bay, West Greenland, is described and compared with the skulls of adult narwhals, Monodon monoceros, and belugas, Delphinapterus leucas. The anomalous whale's skull is much larger than those of normal narwhals and belugas. In particular, the rostrum and mandibles are relatively long and massive. The dentition is unlike that of any known cetacean, but some features of the teeth are considered analogous to those of both narwhals and belugas. The intermediate characteristics of the skull and dentition are consistent with the hypothesis that the anomalous whale was a narwhal‐beluga hybrid.