Several bones from a prehistoric mammal that were uncovered in Carlsbad and Oceanside are now on exhibit at the Agua Hedionda Lagoon Foundation’s Discovery Center. The four bones from a mastodon, a prehistoric elephant-like mammal, are on temporary loan from the San Diego Natural History Museum. The exhibit includes a femur and a vertebra, which were found in August 2002 at the Wanis View Estates in Oceanside and a tusk and molar both found during the excavation for the Robertson Ranch development in Carlsbad in June 2007, according to Samantha Richter, chief operating officer for the Agua...