NEW MYSTICETE WHALE SPECIMEN COULD REPRESENT FIRST OF ITS KIND FROM MIDDLE MIOCENE SITE IN CAROLINE COUNTY, VIRGINIA

Numerous remains of fossil whales have been recovered from the middle Miocene Calvert Formation, yet many have yet to be entered into the published record. In 2009, the Virginia Museum of Natural History excavated a fossil whale skull from the Carmel Church Quarry in Ruther Glen, Virginia. Here we report a species of Miocene mysticete whale that could represent the first of this taxon collected from this site. The site at Carmel Church is well documented, and has yielded many marine fossils from the Calvert Formation, including sharks, fish, crocodiles, odontocete whales, and other mysticetes. This specimen is represented by a partial skull, preserving most of the brain case as well as both ear bones. Also found within the jacket were a radius, a thoracic vertebra, a caudal vertebra, and a single rib, which may or may not belong to the same individual. The site is so rich in marine fossils that associated bones are not always from the same individual. The skull material also includes a partial dentary, partial premaxilla, which appear to be associated with the occipital, frontal, and both squamosals. Despite such limited material, the highly diagnostic petrosals and tympanic bullaewere recovered in direct association with the rest of the cranial material, and articulate very well with the rest of the skull. We have made extensive use of these ear bones to determine the identity of the specimen. The skull and ear bones appear most similar to the basal crown mysticetes Parietobalaena and Halicetus, both known from the Miocene of eastern North America. However, what sets this specimen apart from many other known mysticetes is the small size of the posterior process of the petrosal relative to the anterior process. The petrosals here closely resemble those of Parietobalaena, though this whale’s skull differs from Parietobalaena in the greater anterior extent of the supraoccipital, which nearly comes into contact with the rostral bones. Most of the skull of Halicetus is unknown, which makes further comparison difficult. Further cladistic study will hopefully resolve the new specimen’s relationships within Mysticeti and further develop the increasingly complex Miocene cetacean fauna of the western Atlantic.

Key words: mysticete, Calvert Formation, Virginia, Carmel Church Quarry, Miocene