A fossil right whale skull in profile was recovered in Mission Viejo during grading operations in the southern part of the city in 1976 from the marine siltstone member of the Capistrano Formation, which is 3.5 to 5 million years old. The skull is from the family Balaenidea, which includes bowhead whales and right whales, and is identified as a partial skull of a baleen whale, a member of the bowhead whale family. A vertebral column exhibited behind the skull was also discovered in Mission Viejo, although it is not associated with the skull. When alive, this whale would have been 58 feet long and weighed about 50 tons, or the weight of 575 men, and its skull would have measured nine feet across and about 14.5 feet long. Owned by the Los Angeles County Natural History Museum and on permanent loan to the City of Mission Viejo, it is the only fossil skull of this kind on scientific display in California.
