In 1993, "M. sinocanadorum" was described by Dale Russell and Zhong Zheng. The remains were found in 1987 when a cervical rib was seen projecting out of a cliff. The fossil site was located in the Junggar Basin, Xinjiang; from the upper part of the Shishugou Formation (between 161.2 Ma and 158.7 Ma in age). The specimen (IVPP V10603) consisted of an articulated series of the first four cervical vertebrae, a well-preserved mandible, and other skull material. The mandible was in length and had 19 teeth. In contrast to the more squared-off jaws of diplodocids, the front of the mandibles met at an oblique angle. The neural arches of the vertebrae were well fused to the centra suggesting that the animal was mature. This species possessed the longest cervical rib of any described sauropod dinosaur, measuring . For comparison, a "Sauroposeidon" cervical rib measures . The cervical vertebrae are on average 1.19 times longer than those of "M. hochuanensis;" based on this, Russel and Zheng estimated the type specimen at . The neck has been estimated at in length. The species name refers to the China-Canada Dinosaur Project.