New Mexico Geological Society Annual Spring Meeting — Abstracts

Canovas Creek is a late Pleistocene vertebrate fauna in the Gila National Forest, Catron County, southwestern New Mexico. Canovas Creek is one of the highest Pleistocene fossil sites in New Mexico at an elevation of 2,375 m (7,793 ft). The site was discovered in September 2010 by local resident Chris Wonderly and excavated by New Mexico Museum of Natural History field crews between 2011 and 2014. Vertebrate fossils are abundant in a layer about 50 cm thick, consisting of brown fine sand with silt and clay and occasional large rounded boulders up to 30 cm in diameter. The fossiliferous layer occurs over an area of about 25 m², and dips from the surface to a maximum depth of about 1.5 m in the center of the site where the sediments consist of medium to coarse sand, possibly representing a paleochannel structure.

The most common species in the Canovas Creek Fauna is the extinct horse Equus conversidens, represented by hundreds of isolated teeth, nearly 20 jaws and partial skulls, and about 10 complete limb bones. Second in abundance is the mammoth Mammuthus columbi, known from a pair of lower jaws, partial skull, 2 tusks, an isolated molar, several limb bones, and numerous vertebrae. Although sturdy elements such as isolated teeth, carpals, tarsals, and toes are common, incomplete bones are more abundant than intact fossils and there are thousands of bone fragments. The lack of articulated remains and abundance of broken and waterworn bones suggests the Canovas Creek fossils were transported by water under high energy, perhaps a flash flood, and secondarily redeposited. The rarity of freshwater species suggests the site of deposition was not a permanent water source such as a lake or stream.

The Canovas Creek Fauna consists of 18 species: the mud turtle Kinosternon, 2 birds, and 15 mammals. There are 5 members of the extinct Pleistocene megafauna: the horses Equus conversidens and E. occidentalis, giant llama Camelops hesternus, Stock’s pronghorn Stockoceros, and Columbian mammoth Mammuthus columbi. Two medium-sized carnivores, bobcat Lynx rufus and coyote Canis latrans, still live in the Gila region. Large carnivores are currently unknown from the fauna. Small mammals include: shrew Sorex; 5 rodents, Wyoming ground squirrel Urocitellus elegans, red squirrel Tamiasciurus hudsonicus, northern pocket gopher Thomomys talpoides, woodrat Neotoma, and vole Microtus; and 2 rabbits, jackrabbit Lepus and mountain cottontail Sylvilagus nuttallii. Tamiasciurus hudsonicus, Thomomys talpoides, Sylvilagus nuttallii, Sorex, and Microtus are now restricted to montane habitats in New Mexico and no longer occur in the vicinity of Canovas Creek. Urocitellus elegans inhabits mountain meadows and sagebrush grasslands, and is currently unknown south of central Colorado. These small mammals occurred farther south and at lower elevations during the late Pleistocene when the climate was cooler and wetter. The presence of Mammuthus columbi and several extralimital species of small mammals suggest a late Pleistocene age (Rancholabrean) for the Canovas Creek LF.