This model was originally proposed in 1880 by Othniel C. Marsh. The theory states "Archaeopteryx" was a reptilian bird that soared from tree to tree. After the leap, "Archaeopteryx" would then use its wings as a balancing mechanism. According to this model, "Archaeopteryx" developed a gliding method to conserve energy. Even though an arboreal "Archaeopteryx" exerts energy climbing the tree, it is able to achieve higher velocities and cover greater distances during the gliding phase, which conserves more energy in the long run than a cursorial bipedal runner. Conserving energy during the gliding phase makes this a more energy-efficient model. Therefore, the benefits gained by gliding outweigh the energy used in climbing the tree. A modern behavior model to compare against would be that of the flying squirrel. In addition to energy conservation, arboreality is generally associated positively with survival, at least in mammals.