Their forelimbs were large and strongly built, and the ulna bone had a unique shape in members of the family Megaraptoridae, a subset of megaraptorans which excludes Fukuiraptor and Phuwiangvenator.

The vertebrae, ribs, and the ilium bone of the hip were pneumatized to an extent which was very rare among theropods, only seen elsewhere in taxa such as Neovenator.

[4] By the early 2020s, many studies had come to find that megaraptorans instead represented members of Coelurosauria, with their exact position within this group being uncertain.

At least some megaraptorans, such as Murusraptor and Aerosteon, had extensively pneumatic bones (most noticeably the ilia and ribs), which likely housed sinuses connected to the lungs, similar to modern birds.

[3] Otherwise, the rear part of the skull is rather simple, without any pronounced crests or bosses, although the lacrimal and postorbital bones did have rugose patches in some genera.

[10] The premaxillary teeth of Megaraptor were variably similar to those of tyrannosauroids, being small, incisiform (chisel-like) and D-shaped in cross section.

Megaraptoran maxillary teeth show much variety between genera, although they were generally small compared to the snout with minimal enamel ornamentation.

Opisthocelous vertebrae are also characteristic of Allosaurus[11] and sauropods, and they may facilitate high flexibility without sacrificing defense against shear forces.

[12] Otherwise, the cervicals were similar to those of carcharodontosaurians, with short neural spines, transverse processes (projecting rib facets) located around mid-length on the centra, and a pair of large lateral pits known as pleurocoels.

[4][2] The proximal caudals (vertebrae at the base of the tail) had a longitudinal ridge running along their lower surface, similar to the case in Neovenator but unlike tyrannosauroids.

The gastralia (belly ribs) were wide and strongly built paddle-shaped structures, with the left and right sides fused at the midline of the chest.

In addition, megaraptorids have acquired another long, crest-like structure on the ulna called the lateral tuberosity, which is perpendicular to the blade of the olecranon.

These claws also had asymmetrically-positioned grooves on their flat faces and a sharp ridge on their lower edge in megaraptorids (non-Fukuiraptor megaraptorans).

Their data also suggests these muscle attachments became increasingly pronounced through megaraptoran evolutionary history, being substantially better developed in derived taxa such as Australovenator and especially Megaraptor itself than in earlier genera such as Fukuiraptor.

[2] The ilium (upper plate of the hip) was a heavily pneumatized bone, filled with air pockets and perforated by pits.

However, coelurosaurs and megaraptorans have a much smaller brevis fossa which occupies only a portion of the rear edge of the ilium, and it is mostly hidden from outside observers.

[10] The pubis (front lower plate of the hip) has a much more pronounced scythe-like expansion at its tip, which is over 60% as long as the main shaft of the bone.

This influx of new data in the late 2000s led to several major reanalyses of basal tetanuran phylogenetics, with interesting implications for these taxa.

A study by Roger Benson, Matt Carrano & Steve Brusatte in 2010 found that Allosauroidea (or Carnosauria, as it was sometimes called) included a major subdivision known as Carcharodontosauria, which was split into the Carcharodontosauridae and a newly named family: Neovenatoridae.

Neovenatorids were envisioned as the latest-surviving allosauroids, which were able to persist well into the Late Cretaceous due to their low profile and coelurosaur-like adaptations.

Fukuiraptor and Australovenator were consistently found to be close relatives of each other; this was also the case for Aerosteon and Megaraptor; Orkoraptor was a "wildcard" taxon difficult to place with certainty.

The cladogram below illustrates the most recent revision of the Benson, Carrano, & Brusatte (2010) hypothesis that megaraptorans were allosauroids within the family Neovenatoridae.

[4] The cladogram follows Coria & Currie (2016), who added Murusraptor to the study and utilized the family Megaraptoridae, which was originally named by Novas et al.

[10][18] Allosauridae Fukuiraptor Megaraptor Aerosteon Orkoraptor However, an alternative hypothesis was forming, first published as an Ameghiniana abstract by Fernando Novas et al.

Novas et al.'s arguments were formulated and published in a 2013 review of patagonian theropods, which removed Megaraptora from the Carcharodontosauria and instead placed the group within Coelurosauria.

As Novas et al. (2013) removed Megaraptora from Neovenatoridae, they named a new family, Megaraptoridae, which contained all Megaraptorans apart from the basal ("primitive") taxon Fukuiraptor.

[3] Sinraptor Allosaurus Compsognathidae Maniraptoriformes Dilong Santanaraptor Xiongguanlong Tyrannosauridae Fukuiraptor Eotyrannus Orkoraptor Aerosteon Megaraptor In 2016, Novas and his colleagues published a study of megaraptoran hand anatomy, in an attempt to help settle the question of their classification.

Allosauroidea was rendered a paraphyletic grade, with carcharodontosaurids, Neovenator, a clade formed by Chilantaisaurus and Gualicho, and finally Megaraptora progressively closer to traditional coelurosaurs.

The study returned Neovenator to a monophyletic Allosauroidea, and placed megaraptorans as basal non-tyrannosauroid coelurosaurs close to Chilantaisaurus and Gualicho.

The cladogram below displays the coelurosaurian results of the phylogenetic analyses by Rolando et al.[5] Nqwebasaurus Aorun Compsognathidae Tyrannosauroidea Phuwiangvenator Vayuraptor Fukuiraptor Australian megaraptorid indet.