Sanjuansaurus

Sanjuansaurus ("San Juan Province lizard") is a genus of herrerasaurid dinosaur from the Late Triassic-age Ischigualasto Formation of northwestern Argentina.

Description and Classification
Sanjuansaurus was comparable in size to a medium-sized Herrerasaurus, with a thigh bone that was 395 millimetres (15.6 in) long and a tibia that is 260 millimetres (10 in) in length. Alcober and Martinez performed a phylogenetic analysis and found Sanjuansaurus to be a herrerasaurid.[1] It was determined that Sanjuansaurus and Herrerasaurus share many similarities in the morphology of the skull, neck vertebrae, back vertebrae, hip vertebrae, scapula, and the hip bones. Alcober and Martinez observed that Sanjuansaurus and Staurikosaurus share many similarities in the morphology of the hip bones, and the tibia.The pubis of Sanjuansaurus, unlike in other herrerasaurids, points toward the cranium.

Distinguishing anatomical features
A diagnosis is a statement of the anatomical features of an organism (or group) that collectively distinguish it from all other organisms. Some, but not all, of the features in a diagnosis are also autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to a given organism or group.

According to Alcober and Martinez (2010), Sanjuansaurus can be distinguished based on the following characteristics:

a pronounced, rugose scar is present on the medial surface of the femur at the level of the fourth trochanter
 * the cervical vertebrae have shelf-like, posterolaterally directed transverse processes
 * the neural spines of the sixth to eighth dorsal vertebrae, at least, bear acute anterior and posterior processes
 * the glenoid has everted lateral margins
 * the pubis is relatively short, measuring 63% of the length of the femur

Discovery
Sanjuansaurus was named and described in 2010 by Oscar Alcober and Ricardo Martinez. The type species wan named S. gordilloi after Raul Gordillo, the head fossil preparator and artist of the San Juan Museum. It is known from and based on an associated and partially articulated partial skeleton (PVSJ 605) consisting of a jaw fragment, most of the vertebral column from the axis to the anterior tail, the shoulder blades, an ulna, part of the pelvis, most of the long bones of the legs, and a few other bones.