Mini-Mammoths

Mini-Mammoths. The Island Effect. , Strange Discovery , In 1853, the remains of small "elephants" were discovered on Santa Rosa Island. Over the years the number of remains found continued to grow, and in 1925 this pygmy species was named Mammuthus exilis. These mini-mammoth remains are most common on Santa Rosa and San Miguel Islands, although a small number have been found on Santa Cruz Island, and even on more distant San Nicolas Island. , , Why So Small? , One scientific hypothesis - the "island effect" , suggests that when mainland animals move onto islands, small species (like birds) tend to evolve larger bodies, and large species (like mammoths) tend to evolve smaller bodies. The limited supply of food available on islands may play a large part in this evolutionary trend. Pygmy mammoths, about 6 feet high, were less than half the height of their ancient mainland ancestors. , , Ice-Age Super Island , Until about 10,000 years ago, the four Northern Channel Islands were all joined together as part of a single, super island, referred to as Santarosac. During the Pleistocene epoch - the Ice Ages - there was a drop in sea level, exposing more of the submerged mainland shelf and narrowing the offshore ocean channel. , These dramatic changes made it possible for Columbian mammoths living on the heavily-grazed mainland to swim across the channel to reach fresh island vegetation. As the Ice Ages ended, the sea level rose again, covering lower elevations of land and separating the island mammoths from mainland herds. , , photo captions: , · A 13,000 year old pygmy mammoth skeleton was found on Santa Rosa Island in 1994. Full-sized models of the skeleton are on display at the Santa Barbara Museum of Natural History and at the Channel Islands U.S. National Park Visitor Center in Ventura. , , · The intact pygmy mammoth skeleton, excavated on Santa Rosa Island in 1994, was 5½ feet tall. , , · More heavily vegetated during the Pleistocene epoch, Santa Rosa Island was once home to Pygmy Mammoths. Humans and mammoths co-existed on the island for at least 200 years. , , · The 13,000-year-old skeleton of Arlington Springs Woman, the oldest set of human remains yet found in North America, was found on Santa Rosa Island. , , · Channel Island Fox (Urocvon littoralis) is probably the smallest fox in North America. Its small size is also an adaptation to the limited resources available in the island environment. The foxes are believed to have "rafted" to the islands on floating debris between 16,000 and 10,400 years ago.