SAN DIEGO - Researchers recently determined that fossils, found at a City of San Diego Water Department construction site last fall, belong to a primate group in existence years ago. The discovery occurred as contractors tunneled along the north side of Scripps Lake Drive near the City's Miramar Water Treatment Plant at Lake Miramar to install a new water pipeline.

Most of the fossils consist of upper and lower teeth and sections of both left and right jawbones of primates. The most significant discovery is a specimen consisting of a left lower jaw, right jaw and a right upper jaw fragment of an unidentified species within the genus Ourayia. Researchers from San Diego and Washington University in St. Louis Missouri are currently studying this new primate species.

According to Stephen Walsh of the San Diego Natural History Museum, this specimen provided the first definite association of upper and lower teeth for the genus Ourayia and the complete anterior tooth arrangement of any macrotarsiine taxon (Macrotarsiini includes Macrotarsius, Ourayia and Mytonius). It will likely become the type specimen of this new species of Ourayia, currently unnamed.

The new species was introduced from a previous discovery of several jaw fragments from the Friars Formation, however, the Miramar Tunnel specimen is much more complete. This species is the smallest and oldest known of the genus Ourayia, and is from the early part of the Uintan North American Land Mammal Age, in existence approximately 45 million years ago.

Although the skull and skeleton of the new species of Ourayia have yet to be found, it is likely that this species had life habits similar to those of modern tarsiers (from the genus Tarsius) and lived in a much wetter climate than prevails in San Diego today. Modern tarsiers live only in southeast Asia, in rain forest habitats and appear to have very large orbits to house enormous eyes adapted for nocturnal hunting of insects.

"This is the second recent fossil discovery associated with the Water Department's Capital Improvements Program construction activities," said Water Department Director Larry Gardner. In 2001, ancient shark teeth and corresponding bite marks on a nearby whalebone were found at the Water Department's Bayview Reservoir construction site in La Jolla. "It appears that some of our water infrastructure is located on prehistoric ground," continued Gardner. "We're proud that our environmental staff and construction team took the appropriate steps to identify and preserve the fossils for future research."

The fossils, discovered by Paleontologists Donald R. Swanson and Stephen L. Walsh, were contained in boulder-sized rock fragments that were incorporated into the Friars Formation conglomerate that was excavated during construction. Identified in 1971, the Friars Formation reaches a maximum thickness of 165 feet and extends from Friars Road in Mission Valley up to Rancho Bernardo and Rancho Sante Fe. It also extends from Tecolote Canyon to Santee and Lakeside.

Many construction projects are required to have continuous environmental monitoring, including the screening of possible paleontological material as outlined in the California Environmental Quality Act. The City of San Diego Water Department donated the fossils to the San Diego Natural History Museum for further research.

The Miramar tunneling project is part of the Water Department's Capital Improvements Program. While the tunnel is now complete, other construction activities continue in the area as the City works to upgrade the Miramar Water Treatment Plant that was originally constructed in 1962. More than a half-million customers in the northern communities of the City of San Diego receive drinking water from this plant.

Additional information about other important infrastructure projects can also be found online at www.sandiego.gov/water click on "Departments" and then "Water." Or, contact the Capital Improvements Public Information Line at 619-533-4679 for additional details. For more paleontological information, contact Donald R. Swanson or Stephen L. Walsh at the San Diego Natural History Museum at 619-232-3821.