A DNA analysis of ancient material showed that bighorn sheep went extinct on Tiburón Island off the coast of southern California within the last millennium.
The animal, which is known for its large spiral horns, between the sixth and 19th centuries, a University of California, Riverside news release reported.
The research is surprising because researchers and the indigenous Seri people who have inhabited the land throughout history believed the bighorn sheep had never inhabited the island until it was introduced in the 1970s. The animals were introduced in an effort to find a safe place for them to preserve and expand their population.
"Introduction success was expected on Tiburón Island, given the suitable habitat, lack of predators, absence of domestic sheep and their diseases, and minimal human disturbance," Benjamin Wilder, a Ph.D. graduate student in UC Riverside's Department of Botany and Plant Sciences and the lead author of the study, said in the news release. "Indeed, by the mid-1990s, the Tiburón herd had grown to a stable population of 500 animals, one of the most successful large mammal introductions in the world."
Researchers made the discovery when they stumbled upon a 1,500 to 1,600-year-old, "urine-cemented dung mat on the floor of a small cave in the Sierra Kunkaak," the news release reported.
Jim Mead, a paleontologist at East Tennessee State University and a coauthor on the study compared the newly-discovered sample with his own dung collection, and determined that ancient bighorn sheep created the dung mat.
Researchers then extracted and sequenced mitochondrial DNA from the ancient droppings; the researchers confirmed the ancient animals were bighorn sheep, but their genetics differed from the modern breed populating the island.
"With extended biological baselines, such as the knowledge that the Tiburón bighorn sheep went extinct before, it is possible to refine conservation targets," he said. "Given the cultural and conservation significance of the Tiburón bighorn, actions can be taken to avoid their past fate."
