A general resemblance to the theropod "Allosaurus" was noted by Benton (1992); however there are key differences between the two. The scapular blade of "Piatnitzkysaurus" is shorter and wider than more derived tenaurans. The humerus represents 50 percent of the length of the femur, which is also a primitive condition present among basal theropods. The relative lengths of the ulna in respect to the humerus and femur are also similar to those of basal theropods, which means the forelimbs of "Piatnitzkysaurus" are proportionally longer than in "Allosaurus". Also primitive is the wide contact between the pubis and ischium, a condition that is much different than that of "Allosaurus" and more derived tetanurans, in which contact is reduced. The pubis of "Piatnitzkysaurus" also has a distal foot that is more modestly developed than in "Allosaurus".