The Predatory Ecology of Deinonychus Figure 4. Correspondence Analysis comparing relative proportions of pedal non-ungual phalanges among non-avian theropod dinosaurs. Separation along Axis 1 (64.99% of variation) discriminates cursorial Ornithomimidae from less-cursorial Dromaeosauridae. Troodontidae plot closer to Ornithomimidae than their sister-taxon Dromaeosauridae, indicating a more cursorial habit. Archaeopteryx plots close to Dromaeosauridae, but in a more intermediate position, as do Tyrannosauroidea, Allosauroidea, and Ceratosauridae. The separation of Archaeopteryx from Tyrannosauroidea and Allosauroidea along Axis 2 (13.89% of variation) suggests an additional discriminatory aspect of phalanx proportions. n = 30. doi:10.1371/journal.pone.0028964.g004 Figure 5. Variation in foot proportions consistent with cursoriality or grasping. Cursorial-proportioned feet of Gallimimus (A) and Allosaurus (B) exhibit D-II and D-IV of subequal lengths, with D- IV significantly shorter than D-III. This is contrasted with Deinonychus (C) where D-IV is significantly elongated, being subequal in length to D-III, with distal-most non-ungual phalanges of D-III and IV subequal in length to the preceding penultimate non-ungual phalanx; features consistent with a grasping habit [20]. Scale = 5 cm. Modified from original sources [1,42,100]. doi:10.1371/journal.pone.0028964.g005 Figure 6. Comparison of ginglymoid vs non-ginglymoid articulation facets in first pedal phalanges of Troodon sp. (all dorsal view). The distal articulation facet is ginglymoid in D-II-1 (A; MOR 553S-6.29.9.89), but not in D-III-1 (B; MOR 553S-8.11.9.209) or D-IV- 1 (C; MOR 553S-8.11.92.213). Specimens are derived from a multi- individual bonebed and may not be from the same individual, hence differences in size are not relevant. Scale bar = 2 cm. doi:10.1371/journal.pone.0028964.g006 PLoS ONE | www.plosone.org 5 December 2011 | Volume 6 | Issue 12 | e28964