Theropoda are a clade of saurischian dinosaurs that includes the most speciose extant clade of tetrapods, birds. Non-avian, carnivorous Theropoda, which dominated terrestrial predator niches during most of the Mesozoic, can be subdivided into generalist macropredators, small-prey-specialists and omnivores. The jaws tend to be the primary instruments of predation, the forelimbs are powerful, but limited in their range of motion so as to function as means of prey restraint. Some macrophages (Carnosauria) retained narrow heads and ziphodont teeth, which are ancestral traits of Theropoda, but evolved modifications of the skull and neck to allow advanced killing modes. In others, an increase in cranial robusticity correlates with greater aptitude at restraining prey (Abelisauridae) or crushing bone (Tyrannosauridae) and reduction of the forelimb. Dromaeosauridae had more flexible limbs and hypertrophied claws on both fore- and hindlimbs that may have replaced the jaws as the primary means of prey capture. Some lineages predominantly brought forth small-prey-specialists with jaws adapted to fulfill a gripping function, and in the case of Spinosauroidea this was accompanied by an amphibious lifestyle. A general, but not universal trend towards cursoriality and an increasingly bird-like mode of locomotion is also known in Cretaceous Theropoda.Here you can find the original thesis as submitted in February 2015.