WHALES AND DOLPHINS
Fossil: Undescribed dolphin from Olympic Peninsula
In recent years the Burke Museum has acquired a large collection of fossil whales, including a number of different dolphin skulls. Most were collected by Jim and Gail Goedert from rocks in western Washington that range in age from 35 million to 10 million years old. Jim Goedert, the Burke Museum Affiliate Curator of Fossil Marine Vertebrates, is studying the evolution of marine mammals.
Living dolphins belong to one subgroup of whales called the Odontoceti—whales with teeth, like the orca (or killer whale). Baleen whales form the other group of living whales, called the Mysticeti that have baleen and do not have teeth. In addition, some of the fossil dolphins in the Burke collection belong to an entirely extinct group that have teeth, but also exhibit the arrangement of skull bones similar to that of baleen whales. The few bones that we have from the skeletons found with the skulls show that the animals were the approximate size and shape of living dolphins. Some have very elongate snouts, resembling the river dolphins that swim in the Ganges River (India and Nepal) and Yangtze River (China) today.
These unique fossils from Washington illustrate the evolution of baleen and the eventual loss of teeth in the mysticete group of whales.
Orca, or killer whale
Because we're accustomed to calling the orca a whale, it may come as a surprise to learn that it is actually member of the dolphin family, Delphinidae. The orca is in fact the largest member of this group and the only dolphin found in Puget Sound. Two members of the porpoise family, the Dall's porpoise and harbor porpoise are seen in the Strait of Juan de Fuca but seldom venture further south.
Two distinct populations of orcas live in waters around the Olympic Peninsula. One group consists of three resident pods (large family groups) that feed only on fish and depend heavily on salmon. Resident orcas spend much of their time near the San Juan Islands but are occasionally seen in other areas. The second orca population, known as transients, consists of smaller pods that enter Puget Sound periodically from the outer coastal waters. Transient orcas feed on seals and otters, and in recent years their forays into central Puget Sound have attracted media attention as they made a significant dent in the region's harbor seal population.
Puget Sound's resident orcas have experienced a population decline since the 1970s, but every so often they still offer a breathtaking sight from the shores of the Olympic Peninsula.