A diagram of the difference in forelimbs between Carnotaurus sastrei and Aucasaurus garridoi from NHM.
Relative proportions of forelimb and hind limb in various theropods. Note the extremely reduced forelimbs of Carnotaurus and Tyrannosaurus, in which forelimb length is less than 20% of the hind limb length. Forelimb/hind limb ratio is 46% in Struthiomimus, 61% in Deinonychus, and 96% in Archaeopteryx. This pattern is even more pronounced when phalanges and unguals are included. Carnotaurus modiﬁed from Bonaparte, Novas & Coria (1990); Tyrannosaurus modiﬁed from Heilmann (1927); Allosaurus after Paul (1987); Sinornithoides modiﬁed from Russell & Dong (1993a); Coelophysis, Struthiomimus, Deinonychus, and Archaeopteryx modiﬁed from Padian & Chiappe (1997).
From Middleton & Gatesy, 2000