are proportionately different from the juvenile, being mostly straighter and more ovoid in cross-section. The femoral head is well preserved, although lacking the greater trochanter. The distal end is rather symmetrical when viewed from behind, with two similarly sized condylar surfaces. In the juvenile, the fourth trochanter is completely in the proximal end. The tibia has a well-developed cnemial crest, and is also short and robust. The surface that would have articulated with the astragalus in life has the anterior half raised, and the posterior half lowered. The pectoral girdle is well known. Both the left and right scapulae and coracoids are known, though incomplete. The scapulae are large and robust, and thicken as they near the glenoids. The scapular blades are flat, although they are both convex along the anterior edge. Where the scapulae and coracoids articulate, the coracoids are thickest, and they become gradually thinner as they gain distance from the scapulae. The younger specimen of Patagosaurus possesses a slightly different morphology of the pectoral girdle, with slightly differing proportions, such as a slightly smaller scapular blade. The coracoids resemble Barapasaurus in shape, and differ from Camarasaurus, although they cannot be directly compared with those of Cetiosaurus. The forelimbs of Patagosaurus are only based on three bones from the juvenile specimen, and no manual elements are preserved. The humeri are slender and elongate, lacking great proximal and distal expansions. The incomplete deltoid crest, only shows that it was wide, and likely had a projection below and behind. Like the humeri, the radius is slender, and lacks large expansions on either end. On the edge closest to the ulna, the radius possesses a ridge along its edge, which corresponds to where radioulnar ligaments would have attached. The ulna is complete, although sediment-filled breaks might have altered its original shape. The forelimb of Patagosaurus is much more gracile and different from the robust later sauropods like Camarasaurus and Apatosaurus, and instead resembles more Diplodocus. Classification When originally described, Patagosaurus was identified as a relative of Cetiosaurus in the family Cetiosauridae. It can be distinguished from Cetiosaurus, a similar genus, by features of the ischium and vertebrae. Another genus also identified as a cetiosaurid by Bonaparte, Volkheimeria, was named in the same paper as Patagosaurus. Features uniting the genera were identified in the pelvic structure and vertebrae, specifically the caudal neural spines and the ilium and ischium. These characteristics show that