This is more fallout from my forthcoming paper on the fossil vertebrates of Virginia. There are extensive Pliocene marine deposits in Virginia, particularly along the James and York Rivers. The Yorktown Formation, particularly its oldest member (the Sunken Meadow), has a fair number of vertebrate remains that have so far not been extensively described.
Right whales (family Balaenidae) are one of the more interesting types of animal found in the Yorktown Formation. Right whales have a fossil record going back to at least the Early Miocene in other parts of the world, but so far have not been reported earlier than the Pliocene on the Atlantic coast of North America. But in the Pliocene of Virginia they may be the most common type of baleen whale.
As far as I can tell, the most commonly collected balaenid remains in the Yorktown are tympanic bullae. These are very distinctive in balaenids, as they are rather dramatically compressed when compared to balaenopterid or cetotheriid bullae.
According to Whitmore and Kaltenbach (2008) two genera of baleen whale are known from the Yorktown Formation in North Carolina. The more common is Balaenula, a small extinct genus, and we have at least two of these in the VMNH collection, both from Surry County (top and below):
Westgate and Whitmore (2002) also described Balaena ricei from the Yorktown Formation in Hampton, Virginia (this is the same genus as the modern bowhead whale). There were no tympanic bullae described with this specimen, but Whitmore and Kaltenbach (2008) referred two of the balaenid bullae from the Lee Creek Mine in North Carolina to Balaena (they referred 13 bullae from the same site to Balaenula). In part, the basis for the referral to Balaena was the larger size when compared to Balaenula.
In the VMNH collection, we have at least one balaenid bulla, from James City County, that may represent Balaena:
This specimen is about 10% larger than the largest Balaenula specimen from Lee Creek Mine, but still quite a bit smaller than modern Balaena. It does, however, demonstrate the presence of at least two right whales in Virginia during the Pliocene.
See this archived post for more information on cetacean tympanic bullae.