Instead, taxa with a higher probability of being within the Theropoda may share more specific traits, such as a prominent promaxillary fenestra, cervical vertebrae with pleurocoels in the anterior part of the centrum leading to a more pneumatic neck, five or more sacral vertebrae, enlargement of the carpal bone, and a distally concave portion of the tibia, among a few other traits found throughout the skeleton.

Therizinosaurs possessed large abdomens for processing plant food, and small heads with beaks and leaf-shaped teeth.

Further study of maniraptoran theropods and their relationships showed that therizinosaurs were not the only early members of this group to abandon carnivory.

Several other lineages of early maniraptorans show adaptations for an omnivorous diet, including seed-eating (some troodontids) and insect-eating (many avialans and alvarezsaurs).

Oviraptorosaurs, ornithomimosaurs and advanced troodontids were likely omnivorous as well, and some early theropods (such as Masiakasaurus knopfleri and the spinosaurids) appear to have specialized in catching fish.

[15] The folds helped the teeth stay in place longer, especially as theropods evolved into larger sizes and had more force in their bite.

[18] The coelurosaur lineages most distant from birds had feathers that were relatively short and composed of simple, possibly branching filaments.

[26] The smallest non-avian theropod known from adult specimens is the troodontid Anchiornis huxleyi, at 110 grams in weight and 34 centimeters (1 ft) in length.

Both of these measures can only be calculated through fossilized bone and tissue, so regression analysis and extant animal growth rates as proxies are used to make predictions.

[33] A second method, known as the volumetric-density (VD) approach, uses full-scale models of skeletons to make inferences about potential mass.

During this period, theropods such as carnosaurs and tyrannosaurids were thought to have walked with vertical femurs and spines in an upright, nearly erect posture, using their long, muscular tails as additional support in a kangaroo-like tripodal stance.

An increase in the proportion of the brain occupied by the cerebrum seems to have occurred with the advent of the Coelurosauria and "continued throughout the evolution of maniraptorans and early birds.

[43][44] Shortened forelimbs in relation to hind legs was a common trait among theropods, most notably in the abelisaurids (such as Carnotaurus) and the tyrannosaurids (such as Tyrannosaurus).

Movement at the wrist was also limited in many species, forcing the entire forearm and hand to move as a single unit with little flexibility.

[50] In theropods and prosauropods, the only way for the palm to face the ground would have been by lateral splaying of the entire forelimb, as in a bird raising its wing.

Despite being abundant in ribs and vertebrae, injuries seem to be "absent... or very rare" on the bodies' primary weight supporting bones like the sacrum, femur, and tibia.

Unusual fusions in cranial elements or asymmetries in the same are probably evidence that one is examining the fossils of an extremely old individual rather than a diseased one.

The study described and analyzed four complete natural molds of theropod foot prints that are now stored at the Huaxia Dinosaur Tracks Research and Development Center (HDT).

Neotheropoda was named by R.T. Bakker in 1986 as a group including the relatively derived theropod subgroups Ceratosauria and Tetanurae, and excluding coelophysoids.

Neotheropoda was first defined as a clade by Paul Sereno in 1998 as Coelophysis plus modern birds, which includes almost all theropods except the most primitive species.

They competed alongside their more anatomically advanced tetanuran relatives and—in the form of the abelisaur lineage—lasted to the end of the Cretaceous in Gondwana.

Thus, during the late Jurassic, there were no fewer than four distinct lineages of theropods—ceratosaurs, megalosaurs, allosaurs, and coelurosaurs—preying on the abundance of small and large herbivorous dinosaurs.

[64] The evolution of birds from other theropod dinosaurs has also been reported, with some of the linking features being the furcula (wishbone), pneumatized bones, brooding of the eggs, and (in coelurosaurs, at least) feathers.

[46] By the early 20th century, some palaeontologists, such as Friedrich von Huene, no longer considered carnivorous dinosaurs to have formed a natural group.

In light of these and other discoveries, by the late 1970s Rinchen Barsbold had created a new series of theropod infraorders: Coelurosauria, Deinonychosauria, Oviraptorosauria, Carnosauria, Ornithomimosauria, and Deinocheirosauria.

[46] With the advent of cladistics and phylogenetic nomenclature in the 1980s, and their development in the 1990s and 2000s, a clearer picture of theropod relationships began to emerge.

As more information about the link between dinosaurs and birds came to light, the more bird-like theropods were grouped in the clade Maniraptora (also named by Gauthier in 1986[54]).

[71] It was later re-defined by Martin Ezcurra and Gilles Cuny in 2007 as a node-based clade containing Ceratosaurus nasicornis, Allosaurus fragilis, their last common ancestor and all its descendants.

[72] Mickey Mortimer commented that Paul's original apomorphy-based definition may make Averostra a much broader clade than the Ceratosaurus+Allosaurus node, potentially including all of Avepoda or more.

This new hypothesis also recovered Herrerasauridae as the sister group to Sauropodomorpha in the redefined Saurischia and suggested that the hypercarnivore morphologies that are observed in specimens of theropods and herrerasaurids were acquired convergently.