Occurrence of a squaloid shark (Chondrichthyes: Squaliformes) with the pinniped Allodesmus from the upper Miocene of Washington

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Abstract
During preparation of a new species of Allodesmus from the Montesano Formation (UWBM 75640; presently being described by the writer) at the University of Washington Burke Memorial Museum in 1984, preparator Bev Witte found 14 monospecific elasmobranch teeth (UWBM 75641) in the matrix encasing the specimen. Most of the teeth were found in the matrix surrounding the cervical vertebrae; a few teeth were found near the skull (Figure 1). Unfortunately, the precise location of each tooth in relation to the pinniped skeleton was not recorded during their air-abrasive removal from the indurated matrix. It is known that the teeth were deposited no more than one or two centimeters from the skeleton. One of the matrix blocks freed from the pinniped still contains two teeth that line the inner surface of a mold of an unidentified Allodesmus bone. This is the first published occurrence of a shark from the Montesano Formation. The occurrence extends the range of Squalus occidentalis northward along the northeastern Pacific margin into Washington State, and it is also one of the highest biostratigraphic occurrences for this species. The discovery is additionally noteworthy because of the depositional relationship of the Allodesmus and Squalus, and because tooth marks occur on the Allodesmus skull. The occurrence therefore has taphonomic and paleoecological implications.