In 1987, a Sino-Canadian expedition known as the Dinosaur Project (China – Canada – Alberta – Ex Terra) discovered a large theropod skeleton in the Upper Jurassic Shishugou Formation of the Junggar Basin in northwestern China. The well-preserved skeleton lacks much of the tail and most of the arms, but is otherwise nearly complete. The new genus and species, Sinraptor dongi, represents a poorly understood stage of theropod evolution, even though a related form, Megalosaurus, was the first dinosaur described and named (by W. Buckland in 1824). Sinraptor has a large pneumatopore in the jugal, a pronounced postorbital rugosity, a relatively long intertemporal bar in which the postorbital appears very short in lateral aspect, and a pneumatic palatine. It is more advanced than Piatnitzkysaurus from Argentina, less derived than Allosaurus, and shows its strongest similarities to Yangchuanosaurus. The preorbital skull length of Sinraptor is relatively longer than in Yangchuanosaurus, but the skull is relatively lower. A specimen from Sichuan recently described as "Yangchuanosaurus" hepingensis represents a second species of Sinraptor. Sinraptor and Yangchuanosaurus are united in a new family of theropods, the Sinraptoridae.

Dromaeosauridae is the sister taxon of the Avialae; thus, an investigation of dromaeosaur shoulder girdle musculature and forelimb function provides substantial information regarding changes in the size and performance of the theropod shoulder girdle musculature leading to avian powered flight. Twenty-two shoulder girdle muscles were reconstructed for the dromaeosaurid shoulder apparatus, based on phylogenetic inference, which involves the comparison of lepidosaurian, crocodilian and avian musculature, and extrapolatory inference, which involves a secondary comparison with functional analogues of theropods. In addition to these comparative methodologies, osteological correlates of shoulder musculature preserved in eumaniraptorans are identified, and comparisons with those of extant archosaurs allow these muscles to be definitively inferred in dromaeosaurids. This muscle reconstruction provides a foundation for subsequent investigation of differences in muscular attachment and function, based on scapulocoracoid morphology, across the theropod lineage leading to birds.

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How evolutionary changes in body size are brought about by variance in developmental timing and/or growth rates (also known as heterochrony) is a topic of considerable interest in evolutionary biology. In particular, extreme size change leading to gigantism occurred within the dinosaurs on multiple occasions. Whether this change was brought about by accelerated growth, delayed maturity or a combination of both processes is unknown. A better understanding of relationships between non-avian dinosaur groups and the newfound capacity to reconstruct their growth curves make it possible to address these questions quantitatively. Here we study growth patterns within the Tyrannosauridae, the best known group of large carnivorous dinosaurs, and determine the developmental means by which Tyrannosaurus rex, weighing 5,000 kg and more, grew to be one of the most enormous terrestrial carnivorous animals ever. T. rex had a maximal growth rate of 2.1 kg d(-1), reached skeletal maturity in two decades and lived for up to 28 years. T. rex's great stature was primarily attained by accelerating growth rates beyond that of its closest relatives.

Cryolophosaurus ellioti Hammer and Hickerson, 1994, from the Early Jurassic Hanson Formation of the Central Transantarctic Mountains, represents a theropod dinosaur from a period of time and geographical area that are poorly sampled with respect to dinosaur taxa. An in-depth morphological description of Cryolophosaurus is presented here, along with a rigorous phylogenetic analysis of theropod relationships consisting of 347 characters and 56 taxa, in an attempt to clarify the relationships of Cryolophosaurus and to provide insight into questions surrounding early theropod evolution. Cryolophosaurus is characterized by a unique cranial crest, formed primarily by the lacrimals, a pronounced constriction of the squamosal and jugal bones across the infratemporal fenestra, and extremely elongate cranial processes on the cervical ribs. Several shared characters, including the presence of a slotshaped foramen at the base of the nasal process of the premaxilla, nasolacrimal crests and erect tab-like dorsal processes on the articular, suggest affinities between Cryolophosaurus and a clade of medium-bodied Early Jurassic theropods that includes ' Dilophosaurus ' sinensis , Dracovenator regenti and Dilophosaurus wetherilli . This clade is recovered as sister-taxon to a Neoceratosauria + Tetanurae clade, rendering both a traditional Coelophysoidea and Ceratosauria non-monophyletic. Cryolophosaurus represents the largest known Early Jurassic theropod, and marks the beginning of theropod occupation of the dominant predator niche in the Mesozoic.

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The Late Cretaceous (∼95–66 million years ago) western North American landmass of Laramidia displayed heightened non-marine vertebrate diversity and intracontinental regionalism relative to other latest Cretaceous Laurasian ecosystems. Processes generating these patterns during this interval remain poorly understood despite their presumed role in the diversification of many clades. Tyrannosauridae, a clade of large-bodied theropod dinosaurs restricted to the Late Cretaceous of Laramidia and Asia, represents an ideal group for investigating Laramidian patterns of evolution. We use new tyrannosaurid discoveries from Utah—including a new taxon which represents the geologically oldest member of the clade—to investigate the evolution and biogeography of Tyrannosauridae. These data suggest a Laramidian origin for Tyrannosauridae, and implicate sea-level related controls in the isolation, diversification, and dispersal of this and many other Late Cretaceous vertebrate clades.