(1)University of California Berkeley scientists confirmed that a cluster of fossilized bones found in Silicon Valley are likely the remains of a mammoth. (2)The giant beast would have roamed the area between 10,000 and 40,000 years ago.(3) A pair of elephant-like tusks, a huge pelvic bone and the animal's rib cage were found by an amateur naturalist who was walking a dog along a canal near San Jose's Guadalupe River.(4) It could be the remains of a Columbian mammoth, according to paleontologists who expect to study the site.

Which sentence least supports the main idea?